A slow-revving big-displacement V-8 may perform fine for common street driving while in a slight state of imbalance. However, today’s smaller V-6 and 4-cylinder inline engines are much more reactive to balance condition. Whether an engine machine shop builds street motors or race motors, or a combination of the two, it’s becoming increasingly important to provide a balancing service to properly recondition both low-RPM street motors and high-revving competition motors. Balancing is not for racers only!

For high-performance and racing engine applications, achieving proper crankshaft balance is an absolute must. For engines that experience high engine speeds and sustained high RPM, out-of-balance dynamic forces not only rob horsepower but can also play havoc on components such as main bearings, the crankshaft, rod bearings, rods, and pistons.

Everything that attaches to the crankshaft has an effect on dynamic balance. This includes connecting rods, pistons, piston pins, piston rings, rod bearings, pin locks, and estimated engine oil that will cling to crankshaft counterweights, rods, and pistons.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/engine-balancing-101-everything-you-need-to-know‎

The purpose of balancing, in a nutshell, is to match the crank’s geometric centerline axis to the mass centerline axis. The geometric centerline is an unchanging point of reference. This is the static center of rotation of the crank’s main journals. The mass centerline is the axis that can change, as rotating and reciprocating forces act on the centerline under dynamic conditions.

If the crank’s mass centerline (created by the force of imbalance) is too far out of alignment from the geometric centerline, these two centerlines constantly fight each other. In other words, the crank’s mains are forced to rotate in an eccentric path. This ongoing creation of an offset pressure point can squeeze the oil film out from between bearings and journals. Naturally, the result of a severe imbalance is eventual bearing failure. Don’t think that an engine has to vibrate wildly for this to be a problem. Even small forces, though possibly not felt by the driver, can magnify and, over time, can lead to shortened engine life. Balancing optimizes the operational conditions and is a prime factor in obtaining maximum engine life.

To remedy this serious condition, the crankshaft must be balanced. In the process, the entire rotating assembly must be considered, because of the dynamic effects placed on the crankshaft by the rotating and reciprocating weight (mass) that is moved by the crankshaft. This includes connecting rods, rod bearings, pistons, piston rings, piston pins, and piston pin locks (where applicable). You also need to consider the anticipated weight of oil that clings to the crankshaft counterweights, rods, and pistons.

Rotating weight, or mass, includes the crankshaft and the connecting rod “big” end and the rod’s big end bearings. Reciprocating weight includes pistons, rings, piston pins, pin locks (for full-floating pins), and the “small” end of the connecting rods. By equalizing the weight experienced by the crankshaft, you reduce or eliminate unbalanced reciprocating forces as the crankshaft rotates through its cycles. Engine balancing isn’t required for race engines only. Any engine must be properly balanced to obtain both performance and durability. Performance engines simply require a greater degree of precision balancing to minimize imbalance conditions as much as possible. Consider an imbalance condition of 56 grams (which equals about 2 ounces). At an engine speed of about 4,000 rpm, this results in a force of about 56 pounds of crankshaft deflection. At 8,000 rpm, that force climbs to a scary 224 pounds of imbalance force. The goal is to minimize imbalance as close to zero as practical. It’s important to note that chasing absolute zero is both difficult and unnecessary. Considering the clinging and slinging nature of engine oil, even if you were able to zero balance the crank, it’s not going to run at zero during engine operation. Realistically, balancing a non-high-performance street crank to within less than 4 grams and a performance and/or racing crank to within less than 1 gram is acceptable and practical to achieve with today’s computer balancers.

This is what you need to create your bobweights prior to balancing an internally balanced V-8 crankshaft: the crankshaft, one connecting rod, one piston, one piston pin, one piston’s ring package (including an oil ring support rail, if required for your pistons), pin locks for full-floating pins, and one rod’s pair of bearing shells. This assumes that you’ve already weighed and weight-matched all pistons and weighed and matched all rods. If the crank is externally balanced, you need to add the front dampener/harmonic balancer and the flywheel.

Out-of-Balance Forces  on the Crank

An imbalance condition can place stresses on the crankshaft during engine operation. A few sample charts illustrate these forces. In the first example, I consider an imbalance condition of 1 gram at a radius of 3.25 inches (radius referring to the distance of imbalance from the crank centerline). This helps to understand how imbalance in grams results in pound imbalance during engine operation. Impacts per second and impacts per hour refer to the number of times this force impacts the crankshaft per RPM increases. It’s easy to understand how an imbalance condition can cause the crankshaft to deflect at higher RPM, which can cause main bearing oil clearance to diminish, eventually destroying the bearings, with subsequent damage to main journals. This also places undue stress on block main saddles and main caps. The transfer of energy caused by the imbalance can also impact rod-bearing clearances, with accompanying stresses placed on piston pins and piston pin bosses.

It’s important to note that not only are you concerned with the imbalance value in grams, but the radius as well. The radius refers to the distance from the crank centerline where the imbalance occurs or is corrected. The greater the radius (the farther the imbalance is away from the crank centerline), the greater the force that the crank is subjected to.

If the crankshaft requires a reluctor wheel (for monitoring by a crankshaft position sensor), the reluctor, also called a tone wheel, must already be installed prior to spin balancing the crank.

Connecting Rods

The first order of business involves weighing all rods and pistons. Each connecting rod is weighed on a dedicated and extremely sensitive scale along with an adjustable rod scale stand. Connecting rods are weighed in three steps: big-end weight, small-end weight, and overall weight. On a rod-to-rod basis, weights should be within a maximum variance of 1 gram. Always weigh rods with caps installed and rod bolts tightened to spec. If you plan to upgrade to stronger rod bolts, the bolts that you plan to use must be installed before you start weighing rods.

Performance connecting rods are designed with maximum strength while eliminating unnecessary mass. As a result, there isn’t much material available for weight removal. This side view of a Scat LS rod big end’s rod bolt area shows how little material is present in terms of potential weight removal. As mentioned earlier, today’s rods are designed with maximum strength while minimizing mass. Having no excess material in this area presents a problem on a rod that required weight reduction, but considering how well today’s performance rods are manufactured and pre-weight-matched, this simply isn’t an issue.

Old-school OEM rods feature balance weight pads at both the small and big ends. This provides material removal for weight matching.

Notice the raised ribs on this rod’s cap. These are part of the design to provide big end strength and are not considered “weight pads.”

Never attempt to remove material from a connecting rod’s beams. Any scratches, nicks, or material removal from the beam edges can pose a serious stress riser issue and can weaken the rod.

Here’s the small end (piston pin end) of a performance rod. Even if you needed to remove a bit of weight from the small end to obtain a matched set of rods where the pin ends weigh the same, you’d only be able to remove very little material. If by chance you do “kiss” this area for weight removal, make sure that the oil hole is not burred or obstructed.

Performance aftermarket rods feature laser-etched number identification at each side of the cap parting line. This unique number allows you to keep rods and their caps organized. If you’re dealing with rods that are not marked, use either an ink marker or a light-duty electric etching gun to create marks. Never use number or letter stamps and a hammer, since you could very possibly distort the rod big end.

High-precision digital scales can be extremely sensitive, often influenced by a slight movement of air. The digital scale should be located in an area away from open doors or windows. Stand very still and allow the scale reading to settle down. Then tare the scale to confirm that it’s reading zero weight. When weighing a component, stand still to avoid air movement and allow the reading to settle. Some scales are so sensitive that even slight body movement (waving your arm, moving toward or away from the scale) can cause the reading to fluctuate.

This side view of a performance aftermarket rod clearly shows that there is no “extra” material available for weight removal at the rod’s small end. As mentioned earlier, today’s performance rods manufactured by established makers are so well weight matched out of the box that no weight corrections should be needed.

High-performance rods are already equipped with high-strength rod bolts. If you’re dealing with OEM rods or used aftermarket rods and plan to install new rod bolts, do this prior to balancing, as different rod bolt brands/types could differ in weight as compared to the original bolts.

The rod big end is weighed using a precision scale that is specifically designed for engine balancing. You support the big end on a specialty stand that rests on the scale, and the small end is supported on a separate stand that is positioned next to the scale. When properly set up, the rod is positioned horizontally with the big end and small end centers at the same height. Before weighing the rod, first place the rod big end stand on the scale and press the “tare” button. This negates the weight of the stand, zeroing the scale with the stand in place. This prevents the weight of the stand from influencing the weight reading. Then mount the rod with both ends supported on the individual stands. After the scale is zeroed, record the weight of the big end in grams.

Precision digital weighing scales are offered by several manufacturers, in varying levels of sensitivity. In addition to the scale, you must also have a rod support stand that is placed on the scale and a rod support adjacent to the scale. This allows you to weigh rod small ends and big ends while one end of the rod is supported off of the scale. Shown here is a scale set offered by Goodson Tools & Shop Supplies.

When setting up a connecting rod on a digital scale, it must be suspended level so that both the small end and big end bore centerlines are at the same height. Here the small end height is adjusted.

A small bubble level aids in adjusting the rod’s state of level.

The off-scale support is adjustable to allow leveling the rod when weighing either end.

This photo shows the rod’s small end being weighed. Again, the on-scale stand has been zeroed so as not to include the weight of the stand. The small end is placed on the stand, while the big end is supported off-scale. The support bushing that engages into the big end bore is simply swapped onto either stand as needed.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/engine-balancing-101-everything-you-need-to-know‎

All weigh scales accomplish the same task. Shown here is a model that features an off-scale support stand where the unweighed end of the rod is suspended by an adjustable chain.

An example of weighing a rod big end. A support stand is placed onto the scale platform and zeroed out (by pressing the tare button). The big end is then placed on that stand, while the small end of the rod is suspended on a stand that is not on the scale. The remote support stand is adjustable for height to level the rod centers.

Remove the rod from the stands and, if necessary, install a smaller-diameter bushing on the stand (some scale stands feature two different bushings, one for big ends and one for small ends). If you change the bushing on the stand that rests on the scale, install that bushing and once again tare the weight to zero the scale. Next, install the rod with the small end on the scale stand and the big end supported by the adjacent stand. Adjust the rod so that the small and big end bore centers are on the same horizontal plane (level). Note the weight of the small end and record this in grams.

Perform these steps for each rod, using a felt marker to record the weights on each rod (or carefully organize the rods on a large sheet of paper with the weights recorded next to each rod. If weight deviations are noted that are greater than 1 gram, you may need to remove weight from the heaviest ends to lighten ends that are too heavy, to match the weight of the lightest rod. In practical terms, weight variations under 1 gram are certainly acceptable. Chances are, the only instance that you need to remove weight to equalize rods is when you’re dealing with older original equipment rods that feature weight pads.

Old-design OEM connecting rods likely require weight matching by removing material from all but the lightest rod big ends and small ends. When grinding a rod, follow the “grain” of the metal. Here the sides of a rod big end are being ground to remove a few grams, in the area where the cap meets the rod. Notice that the grinding wheel is contacting the rod in a vertical orientation. If you grind perpendicular to the rod, you can create unwanted stress risers. Even after grinding in the correct plane, be sure to bead blast and polish the ground surfaces to eliminate potential stress risers.

Again, considering today’s high-quality performance aftermarket rods, it is extremely rare to find a set of rods that are not already weight matched. The objective is to obtain a set of rods that are weight matched. When using OEM production rods, although today’s mass production rods are much more accurately matched by weight than in previous decades, it’s not uncommon to run into a set of rods in which a few are under- or overweight. Considering that many OEM rods are made in a mold using a pressure-cast “powdered metal” construction, it may be difficult to weight-match rods by removing material from rods that are too heavy, because there may not be enough material removal availability without weakening the rods. In those cases where you are forced to use OEM rods, to achieve a matched-weight set, you may need to obtain several additional rods, weighing each, to achieve a weight-matched set. The goal is to have all rod small ends match to within .5 gram. The same holds true for rod big ends. Equalizing the weight of rod big ends benefits rotating balance. Equalizing rod small end weight benefits reciprocating balance.

In the “old days,” it was common practice to correct connecting rod and piston weights by removing material from the rod big ends and small ends (most rods featured a “weight” boss at each end where material could be removed on a grinding wheel. By the same token, pistons could be weight matched by carefully removing material from the underside of the pin boss areas.

Thankfully, because of the precision manufacturing techniques of CNC, today’s performance aftermarket rods and pistons rarely require modifications to achieve rod-to-rod or piston-to-piston weight matching.

If you do need to remove weight from rods, this should be done on a grinding wheel. If you’re removing material from a weight boss on the bottom of the cap, or from a weight boss at the top of the small end, you can lay the rod flat on the feed table of a bench disc sander or grinder, and use the flat side of the wheel during material removal.

If you’re removing material from the bolt sides of the rod, the grinding wheel should make contact parallel to the surface (making the grinding scratches run in a direction from the top of the bolt toward the bottom of the bolt area). Don’t grind perpendicular/90 degrees from the length of the rod, as this can create stress risers. After grinding, any disturbed surfaces should be glass bead blasted and polished to remove any scratches. Depending on the design of the rod, you may not have enough material from which to grind. Avoid removing material that could weaken the rod. If removing material from the bolt sides, avoid removing material at the parting line. If the shoulders provide enough material, you may be able to carefully remove material from the upper shoulders.

Again, you want to avoid reducing rod strength. Carefully remove a very minute amount of material and reweigh, repeating until the big end and/or small end matches the weight of the lightest rod in your set. You can easily remove weight but you cannot add weight, so take your time. If you make a mistake and remove too much weight, that rod now becomes your lightest, making it necessary to match the remaining rods to that lightest rod. Grinding any surface of a rod creates scratches, which can result in stress risers. After grinding, you should bead-blast the ground surfaces and/or polish to remove or reduce these scratches.

When grinding material from a rod big end, always keep the rod cap in place and fully torqued to spec. Today’s performance aftermarket rods are designed with minimal material while maximizing strength. As a result, there probably isn’t much material available at either end to remove without weakening the rod. Because quality performance rods are made to such exacting tolerances, as I mentioned earlier, a set of rods is so closely matched in weight that you likely don’t need to touch them.

Performance aftermarket rods are always laser etched with matching numbers on the rod and its cap. Never mix rods and caps. If your rods are not marked, use an etching pen on one side of the rod big end, above and below the cap parting line (for example, 1, 2, 3, 4, etc.). Avoid stamping numbers onto rods with a number stamp and a hammer. It’s too easy to potentially distort a rod. Always etch numbers, if necessary, onto one side of the big end, parallel with the rod bolt. Never stamp or etch onto the rod beam, and don’t use a file to cut notches onto the rod. File cuts can result in potential stress risers.

Rod bearings from the same set match in weight, so there’s no need to scale weigh all bearings. Simply weigh one rod’s pair of bearing shells when making up the bobweight card.

Also, if you plan to run original/stock rods and plan to upgrade the rods with stronger aftermarket high-performance rod bolts, install the new bolts first before weighing the big ends. Just remember that prior to final weighing the individual components and making the bobweights, all modifications to rods and/or pistons must be performed first. Changing the weight of these components after balancing affects crank balance for the worse. Pistons and rods must be in a ready-to-install state before you make the bobweights.

One rod’s bearings are weighed. This weight is recorded on the bobweight card.

High-quality, high-performance forged pistons are often CNC machined to provide maximum strength while removing unnecessary weight to reduce mass. Pistons, such as those made by JE as shown here, optimize strength-to-weight ratio and leave little if any material for removal. Because these pistons are designed to a high degree of precision, they are already weight matched out of the box, with no need to perform any weight corrections.

Pistons

When weighing pistons, there’s no need for a special stand. Make sure that the scale surface is clean and tare the scale before placing a piston onto the scale pad. Each piston and its pin may be weighed together as a package or individually. Weighing each piston along with its pin is more convenient. If minor weight differences are found, mixing and matching pins to pistons may be necessary to obtain equal weight-matched piston and pin combinations. As stated earlier, when you’re dealing with today’s high-quality performance aftermarket pistons, chances are that each piston in a set weighs the same, as does the piston pins that are included with the piston package. However, it’s best to weigh each and every piston and pin simply to verify weight match, rather than assuming that all pistons and all pins weigh the same. After weighing each piston, mark the dome or boss with a felt-tip marker to note its weight.

It’s always a good idea to weigh each piston to verify weight, but if a set of new forged pistons from any of the leading performance piston makers is selected, you shouldn’t need to make any modifications.

If the pistons feature a short compression height that results in the pin bore intersecting the oil ring groove, a support rail is required at the bottom of the ring groove to provide oil ring support in the void areas that are open to the pin bore. When weighing your ring package, be sure to include a support rail when making up the bobweight card.

Before balancing, it’s a good idea to verify valve-to-piston clearance during test fitting, just in case any valve reliefs need to be enlarged or deepened. If you later discover a need for increased relief, you will likely want to rebalance the crank.

If you’re dealing with budget- priced pistons or older-generation OEM pistons, you may very well find differences in weight. When you’re dealing with a set of pistons, always use the lightest piston as the reference goal. Weight can then be removed from heavier pistons to obtain a set that is weight matched. If weight does need to be removed, only remove material from the underside of the pin boss. This can be done by carefully drilling one or more shallow holes in the boss. Don’t get carried away. Start with a relatively small drill bit, perhaps 1/8 inch in diameter, and drill to a maximum depth of about 1/8 inch, and reweigh the piston. This gives you an idea of how much weight removal that specific relief provided. Continue as needed by moving to a larger-diameter drill bit and performing small-increment material removal, weighing after each step until that piston’s weight matches the lightest piston.

An alternative is to chuck the piston in a dedicated piston vice and carefully mill material from the underside of the pin bosses. Remember: it’s easy to remove material, but it is impossible to replace weight. As I mentioned earlier, with today’s high-quality aftermarket performance pistons as offered by leading piston makers such as JE, Mahle, Ross, Icon, Diamond, CP, etc., you don’t need to correct for weight. Ideally, all piston and pin combinations should weigh exactly the same; as long as weight variations are within a range of less than 1 gram, you’re good to go.

If a piston, generally an OEM style, features enough material at the underside of the pin bosses, weight may be removed here by securing the piston in a dedicated piston vice and machining across the pin bosses. Make very small cutting passes and reweigh often to avoid removing too much material. If you go a bit too far, a heavier piston is the lightest piston and you need to start over by correcting the remaining pistons.

Weigh one piston’s ring package. If the piston requires a support rail, make sure to include the support rail as part of the ring package.

If you are unable to equalize rod small end weight and piston weight, experiment by matching heavier pistons to lighter rod small ends, or heavier rod small ends to lighter pistons. If this provides satisfactory weight matching, you need to label each piston and its matching rod so that they stay together during final assembly.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/engine-balancing-101-everything-you-need-to-know‎

If rod pins do not weight match, use the lightest pin as the reference. Before attempting to remove any material from the pins, first try mixing and matching pins to pistons, for example, pairing the lightest pin to the heaviest piston, etc. You may be able to establish a combination for all piston and pin pairs that allows you to create matching-weight piston/pin combinations without the need to remove material from either pistons or pins. If necessary, material may be removed from heavier pins by carefully chucking the pins in a lathe and lightly kiss-chamfer-cutting material from the ends of the inside diameter. Again, if you’re dealing with current-day high-performance aftermarket pistons and pins, this isn’t necessary due to the extremely close tolerances employed during manufacturing. In the past 20 years or so, I’ve never run into a set of pistons or pins made by leading manufacturers such as JE, Diamond, Mahle, Ross, Keith Black, Icon, etc., that are not already weight-matched.

Don’t weigh the piston rings straight out of the box. After the block cylinders have been honed to final size, check ring clearance of all top and second rings. If the rings need to be file-fit to obtain correct ring end gap, the rings must be filed first before weighing them. Granted, the amount of weight removed by filing may be minuscule, but just make sure that the rings are in the condition of properly fitting the cylinders before weighing them, in case any file fitting is involved.

Also, keep in mind that pistons may or may not feature specialty coatings, such as ceramic thermal barrier coating on domes and anti-friction coatings on skirts. If the pistons are already coated, they’re ready to be weighed. If the pistons are not currently coated, but you plan to send them out to be coated, wait until they’re coated and then weigh them.

Pistons can be weighed separately, without the pin and/or locks. If you choose, each piston can be weighed in combination with its pin and pin locks. If this is done, make sure to keep that pin with that piston. If the piston and rod assembly uses a free-floating pin, where both the piston and rod are free to rotate on the pin, pin locks or buttons are required to secure the pin in place during engine operation. If locks are required, they must be weighed and factored into the bobweight data.

These coatings don’t increase weight dramatically, but it just doesn’t make sense to weigh them while bare when you know that these coatings will be added later.

One point that I’m trying to make is that, although high-quality aftermarket performance rods and pistons are likely already weight matched, don’t assume anything. Just to be safe, take the time to weigh each rod and each piston. You’ll probably be wasting your time, but you’ll feel better after you verify this.

Engine Styles

Not all engine balancing requires the use of bobweights. Engines that operate the crankshafts  in a single plane such as inline 4- and inline 6-cylinder engines, or opposing-cylinder engines (as found in Porsches), have opposing rod throws that run in only one plane. Balancing these engines simply involves balancing the crank by itself, and then weight-matching rods and pistons/pins, with no need to factor in the weight of the reciprocating assembly when balancing the crank. V-style engines involve multiple planes of force, requiring counterweights to compensate for the reciprocating weight of the rods, pistons, pins, rings, and rod bearings. These engines require the use of bobweights to represent the mass of the rods, pistons, etc., during crank balancing.

Bobweights

To balance a crankshaft, you need to create “bobweights” that attach to each of the crank’s rod journals, to simulate the weight that the crank experiences in operation.

In order to create these bobweights, you first need to create a bobweight card. The card lists the weight (in grams) of the components that will be installed onto the crankshaft during assembly. As noted, this includes connecting rods, rod bearings, pistons, wrist pins, piston rings, piston pin locks, along with the estimated weight of engine oil that will cling to these surfaces. As each component is weighed on a digital balancing scale, you record the weights on the reference, or bobweight, card.

There is no need to weigh each piston ring set or each rod bearing, because these components are always closely matched in weight. Any difference is so negligible that it doesn’t affect balance. That’s why it’s only necessary to weigh one piston’s set of rings and only one rod’s bearings.

After the rods, pistons, and pins have been weighed and recorded, weigh one rod’s pair of bearings and record this on your bobweight card.

A sample bobweight card. You include 100 percent of the rotating mass (both rod big ends and both rod bearings that share one journal) and 50 percent of the reciprocating mass (one rod small end, one piston, one set of rings, one set of pins, one set of pin locks).

When both bobweight halves are verified for weight, weigh the pair and verify that it meets your total bobweight requirement.

Both sides of a bobweight must be of equal weight. If, for example, total bobweight needs to be 2,000 grams, each half of the bobweight must weigh 1,000 grams. Assemble each bobweight half to the appropriate half-weight and weigh each half of the bobweight.

Weigh one piston’s pin locks (if featured) and record. Weigh one piston’s set of rings, which includes the top ring, second ring, and oil ring set. If your pistons feature a fairlyshort compression distance where the pin bore intersects with the oil ring groove, you also have an oil ring support ring for each piston. Weigh the entire set of rings for one piston and record this weight.

The bobweights are composed of two-piece aluminum plates that each feature a “V” notch that attaches to the crank rod journals. These plates accept the bobweight that simulates the weight of the rods, pistons, pins, rings, rod bearings, and anticipated oil-cling that the crank deals with during operation. There are two basic types of bobweight designs, one featuring hollow tubes that are filled with lead or steel shot, and another style that features weighted shim discs that slip over the bobweight studs.

To create a bobweight on a V-8 or 90-degree V-6, you consider 100 percent of the rod throw’s rotating weight (the big end of the rod and the rod bearing) and 50 percent of the reciprocating weight, which includes a piston, rod small end, rings, wrist pin, and locks. For other engine configurations, different percentages of the reciprocating weight may be required for use. The manufacturer of the balancing equipment usually provides a reference chart or has this information programmed into its computer software.

When the total bobweight is determined, the weights are assembled to duplicate the real-life reciprocating mass.

Installing Bobweights

The bobweight must be installed perpendicular to its rod pin. In other words, install the bobweight to simulate an opposing pair of rods 90 degrees from TDC of the rod throw. With the specific rod journal positioned upright at TDC while on the balancing machine’s V-blocks, position a bubble level on the top surface of the bobweight clamp flat surface and adjust the bobweight to level before fully tightening it onto the journal.

Bobweights attach to the crankshaft’s rod journals with aluminum V-block clamps that align together on sliding pins. Because aluminum is softer than the crankshaft’s surface, this does not damage the journal bearing surfaces. Naturally, both the clamps and the journals must be clean prior to installing the bobweights.

Bobweights must be installed to the crankshaft perpendicular to each of the crankshaft’s rod throws. With a rod throw positioned at twelve o’clock, a bubble level is placed on the bobweight clamp to assist in obtaining a 90-degree location.

An easy and quick way to center the bobweight onto the journal is to temporarily install an aluminum spacer that takes up half of the total width difference between the bobweight clamp and the journal width. Note the spacer installed here. This allows you to sandwich the spacer between the end of the journal and the clamp. After the bobweight clamp is secure, the spacer is removed.

Each bobweight must be centered, front to rear, on each rod journal. Installing bobweights too far forward or rearward affects balance and provides a false reading.

Here’s another view of the centering spacer in place. This saves time as compared to using a ruler or caliper to center the bobweight clamp. Even though the bobweight clamps are aluminum and softer than the steel journal, always make sure that the journals and the clamps are clean prior to installation.

Some balancers feature a strobe light to monitor crank angle. Note the small timing wheel.

Also, and this is often overlooked, the bobweight must be centered on the crank’s rod journal, with equal distance between the front of the bobweight clamp to the adjacent crankshaft face and the rear of the bobweight clamp to its adjacent crank face. An easy way to do this is to make a centering shim that you can slip onto the journal, between one side of the bobweight clamp and the adjacent counterweight. As an example, if the distance between a journal’s boss faces is 1.90 inches, and the bobweight clamp is 1-inch thick, insert a U-shaped shim that is .45-inch thick onto the journal, on either side of the bobweight clamp. Sandwich the bobweight clamp and spacer together and tighten the bobweight clamp to the journal, then remove the shim. Instead of spending time by measuring, a premade shim (for the specific rod pin length of the crank) makes it easy and quick to obtain a centered location for the bobweight. By not centering the bobweight on a journal, you could end up with a difference of a few grams from front to rear of the crank. If the bobweights are installed toward the rear of the journals, you end up overbalancing the rear of the crank and underbalancing the front. The difference may or may not be harmful, but centering the bobweight eliminates this variable.

4-Cylinder Inline Engines

When balancing a 4-cylinder inline engine, you have opposing strokes (two up and two down), so the forces cancel each other out; you don’t need to create bobweights. Simply weight match the reciprocating parts (rods, pistons, etc.). Then spin and balance the crank without adding bobweights. Weigh the pistons and pins separately. You can then match pistons to pins to “even out” the piston/pin set weights, thereby reducing the time needed to machine weight from pistons (match the lightest piston with the heaviest pin, etc.).

Crankshaft

The crank can’t be final-balanced alone. Performing a static balance of the crank means that only the weight is distributed evenly around the center of rotation. The crank must be dynamically balanced to compensate for the rotating force of the rod big ends and the reciprocating forces by the rods, pistons, rings, etc., to correct for centripetal force.

Some crankshaft balancers feature a safety bar (note the black loop next to this crank’s rear flange). This does not contact the crank. It simply provides a fail-safe to prevent the crank from jumping off the balancer in the unlikely event of a severe crankshaft wobble.

Crankshafts are spun via a belt driven by the balancing machine’s electric motor. Always wear safety glasses during spin balancing to protect your eyes from potential airborne particles. If you have drilled the outer edge of a counterweight and have added a slug of heavy metal, spinning the crank before welding the slug presents a possible danger if the slug accidentally leaves the crank. If weight was added to a counterweight outer edge, don’t stand in front of the crank during spinning until the slug is secured with a weld. Some machinists use temporary sticky putty on the counterweight (creating a specific weight on the digital scale) to perform a test spin. Because the putty can sling off, this is another reason to avoid standing directly alongside the crank during the spin.

Centripetal force (not to be confused with centrifugal force) is created by crankshaft imbalance, where the imbalance force tries to deflect the crank back and forth during operation. This back-and-forth stress can result in main bearing damage or even crankshaft fracturing. By dynamically balancing the crank, you lighten the heavy side or add weight to the lifter side to eliminate centripetal force.

A computer balancer, depending on design, can be used to record individual weights from the bobweight card data and display final bobweight requirements.

If the specific balancing machine does not provide a drill press, the bobweights must be removed and the crank then placed on a V-block fixture at an overhead drill press for weight removal. This is followed by moving the crank back to the balancing machine and reinstalling the bobweights to recheck the dynamic balance.

A balancing machine that incorporates a built-in drill press provides convenience and saves time, avoiding the need to relocate the crankshaft to a separate drill press.

Whenever drilling a counterweight edge to remove weight, always place a clean shop rag on the adjacent journals to prevent contamination.

Depending on where weight removal is most appropriate, instead of drilling to remove all or part of the weight required, the outer faces of the counterweights can be machined on a precision lathe. If the balancing machine indicates that weight should be removed from a larger radius, lathe cutting can save some time.

Handy reference charts are available that tell you what diameter and depth of hole is needed to remove a specific amount of weight, pretty much eliminating guesswork. The balancer tells you how much weight needs to be removed and at what location on a counterweight.

Here an aftermarket crank for a big-block Mopar application is “kissed” on a lathe. The alternative is to drill a series of shallow holes along the edge of the counterweight.

A dynamic balance involves balancing the crankshaft in two planes (as opposed to static balance in a single plane). A dual-plane balance involves both ends of the crankshaft, where balance correction at one end directly affects balance at the opposite end.

Most crankshaft dynamic balancing machines spin the crankshaft at about 750 to 1,000 rpm, at a speed that is sufficient to obtain imbalance data.

If you’re chasing dynamic balance and trying to get picky, there are times when only a very small amount of material removal is desired, which can be handled by hand grinding an area of a counterweight. If using a handheld grinder, cover the adjacent journal with a clean shop rag, and be very careful. One slip could nick the journal.

In this case, the rear counterweight required a heavy weight placed close to the crank centerline at a small radius. To drill the hole, a hole was required at the rear flange to access the counterweight. This was done with the crank anchored vertically on a drill press.

Here a slug of heavy metal is carefully interference fit into a counterweight. The pass-through hole, required for drilling the affected counterweight and to install the heavy slug, is then filled or another hole drilled to offset this first hole.

A close-up view of the installed slug of heavy metal. Installing tungsten through a counterweight enables you to work closer to the crank centerline and eliminates the potential for the weight slug to sling off of the crank during engine operation. If a tight interference fit isn’t possible, the weight is then tack welded to the crank to make sure that it doesn’t dislodge.

The crankshaft is typically spun at a speed of approximately 750 to 1,000 rpm, sufficient to develop forces that are measurable.

Setting up the crankshaft on the spin balancer involves entering the radius from the crank’s centerline to the outer radius of the counterweights, as well as the distance between the centerline of counterweights. A computer balancing machine then determines the balance condition at each front and rear counterweight and provides the operator with the necessary information regarding the amount of weight that needs to be added or removed, and the location of that modification.

Heavy Metal

When weight must be added to a crankshaft, a special “heavy metal” slug is used. This material is also referred to as “Mallory” metal. In essence, this material is composed of a heavy tungsten alloy, which is a little more than twice the weight of steel of the same dimensions. Because this material is heavier than steel, it allows you to use a smaller-dimension slug to provide the needed weight. Unlike lead, tungsten is weldable, environmentally friendly, and withstands shocks and heat.

When you select an aftermarket performance crankshaft, you need to know the “target” bobweight. This is the approximate bobweight that the particular crank likely requires. If the target weight isn’t included on a spec sheet with the crank, consider calling the maker and asking. If your required bobweight is heavier than the crank’s target weight, you likely need to add a bit of a heavy metal. In that case, make sure that you have slugs of tungsten on hand. If your bobweight is the same or lighter than the crank’s target weight, you likely only need to remove material to balance the crank.

Under- versus Over-Balancing

For various racing applications, a common balancing “trick” is to underbalance or overbalance the crankshaft to best suit a specific engine RPM range. Although not suitable for a street performance application, where engine balance needs to provide suitable state of reduced harmonics from idle through occasional high-speed operation, under- or overbalancing allows the machinist to minimize harmonics in a predetermined engine RPM range. This is applicable for engines that typically run only within a specific RPM range (for example, due to the nature of the racing series, the engine may operate only within 6,000 to 8,000 rpm). A slight vibration or harmonic at idle or low-RPM is acceptable, since the vehicle doesn’t run at these lower engine speeds on the track.

Under- or overbalancing may or may not be beneficial on all race engines built for the same purpose, due to variations in valvespring stiffness, timing chain, or timing gear harmonics, etc. Basically, in the case of certain race engine applications, you simply don’t care about vibrations at engine speeds that aren’t used on the track, as long as you can dial-in the balance to optimize engine operation at a very specific engine speed that the engine experiences during competition.

Some race engine builders prefer overbalancing by 1 or 2 percent for a high-revving engine and are convinced that this produces more power. In theory, overbalancing can serve to dampen valvetrain harmonics at a specific engine speed. To overbalance, instead of using 50 percent of reciprocating weight when making the bobweights, you might use 52 percent of reciprocating weight. If underbalancing is desired, the bobweight’s reciprocating weight might be 48 percent. Again, under- or overbalancing is often a trial-and-error approach, unless an engine builder has developed a specific routine in his builds (valvetrain geometry, spring pressures, timing system, camshaft, etc.) where under- or overbalancing has proven to be successful.

External versus Internal Balancing

A crankshaft, depending on engine design, may be internally or externally balanced. Internal balance refers to a crankshaft where all balancing (removal or addition of weight) occurs on the crankshaft counterweights and requires the use of zero-balanced crank dampener and flywheel. Of course, this assumes that the pistons, rods, etc., are already weight matched. When an internally balanced crankshaft is placed on the crank balancing machine, there is no need to attach either a front dampener or flywheel, because an internally balanced crankshaft requires the use of a zero-balanced dampener and a zero-balanced flywheel.

An externally balanced crankshaft uses a weighted dampener and weighted flywheel (where each features a balancing weight or pad). In this case, the dampener and flywheel must be attached to the crankshaft during spin balancing of the crank.

With an internal balance, because the dampener and flywheel are zero balanced and do not affect crank balance, the dampener and/ or flywheel may be replaced during servicing at any time without affecting crankshaft balance (provided you always install a zero-balanced dampener or flywheel).

Late-model engines commonly feature a toothed reluctor wheel that provides a crankshaft position reference for electronic engine management. If the wheel was removed for any reason or a new crank did not feature an already-installed wheel, make sure that the wheel is installed onto the crank prior to balancing. Adding a wheel after balancing could result in an imbalance condition. If the crank is designed to use a reluctor wheel, it must be in place before attempting to balance the crank.

Dampeners and Flywheels

If the crank is internally balanced, the crank dampener and the flywheel must be zero balanced. This can be done on the balancing machine with special arbor fixtures to secure the units separately. However, a convenient approach is to mount them to the crank, after the crankshaft has been balance corrected. If the dampener and/or flywheel aren’t precisely zero balanced already, any imbalance is then discovered and corrected on the dampener and on the flywheel, without any further correction to the crank itself. If this approach is taken, the dampener and flywheel must be reinstalled in exactly the same clock positions used during balancing. If the crank snout is keyed, the dampener only installs in one location anyway (examples of exceptions are OEM LS engine crank dampeners that are not keyed). The flywheel may or may not be indexed to only bolt onto the crank in one location only. If not, place a permanent matchmark on the flywheel and crank flange.

If the crankshaft harmonic balancer features an offset weight pad, this clearly indicates that the crankshaft is to be externally balanced. Unlike an internally balanced crank where the front dampener and flywheel do not need to be installed to the crank during balancing, a weighted dampener must be installed to the crank. If the dampener is replaced down the road, the crank should be rebalanced with the new dampener in place.

A flywheel/flexplate that features welded-on weight was intended for an external balance. For example, if you purchased a rotating kit with crank, rods, pistons, rings, bearings, and flywheel, the weight on the flywheel was added to externally balance the crank. If you’re performing an internal balance job, be sure to obtain a flywheel that is already zero balanced.

If you purchase zero-balanced dampeners and flywheels from reputable makers, checking them probably isn’t necessary, but if you really want to be picky and to verify balance, it’s worth considering.

Viscous Dampeners

A viscous-type harmonic dampener is different than an OEM-type elastomer-dampened unit. And as such, you need to be aware of the following. A viscous dampener (ATI, Fluidampr, etc.) takes advantage of the centrifugal force created by a captive fluid inside the dampener ring. Although an elastomer-ring type dampener is designed to only cancel a crankshaft’s harmonic vibrations at a predetermined frequency range, a viscous-type dampener is designed to cancel harmonic vibrations at any RPM.

As far as crankshaft balancing is concerned, here’s what you need to know: if the engine is an internally balanced design (where all of the crankshaft balancing occurs at the counterweights and the dampener and flywheel are zero-balanced on their own), the viscous dampener itself is already balanced, so there’s no need to perform any balancing work on the dampener at any time. If the engine is an externally balanced design (where the front dampener and the flywheel are integral components of crank balance), the viscous dampener consists of two parts: an outer dampener ring and a center hub. Disassemble the dampener to separate the ring from the hub. Mount only the hub to the crank snout (along with the flywheel at the rear crank flange) for crankshaft balancing. Do not attach the viscous dampener ring to the hub for balancing.

In short, never install a viscous-type dampener or dampener ring to a crank for spin-balancing because the centrifugal internal action of the dampener’s fluid serves to absorb and mask some of the crank’s harmonic disturbances and results in a false spin-balance reading.

Even if the crank is to be internally balanced, and even if you trust the dampener hub to be zero balanced, installing the dampener’s hub to the crank during the balancing setup can’t hurt, and you are able to compensate for any slight deviation of hub balance with the hub in place. If the hub is not keyed to the crank snout and relies only on an interference fit, be sure to place matchmarks on the hub and crank before removing the hub from the crank snout, so that the hub and dampener assembly is final-installed in the same clock position during final engine assembly.

Clutch pressure plates can be checked for balance by mounting the pressure plate to an already-zero-balanced flywheel on a balance arbor. Any weight correction is made by welding weight onto the pressure plate cover. Again, quality pressure plates should already be zero balanced from the factory, but checking, and correcting if necessary, eliminates a potential customer’s complaint of vibration.

If a torque converter is to be checked or corrected for balance, the fluid must be drained first. If the converter does not feature a drain plug, you may drill and tap a hole and install a plug, but if you do that, you should install an identical plug 180 degrees from the first plug to negate the weight of the first plug. If fluid remains in the converter, your spin balance readings aren’t repeatable as the fluid slings around inside. Quality torque converters should already be balanced, so you really shouldn’t need to spend time trying to balance them.

A viscous dampener features an internal cavity with a special silicone fluid that slings around inside and offsets harmonics. Never mount a viscous dampener onto the crankshaft during spin balancing, as this type of dampener may mask vibrational harmonics in the crank.

Written by Mike Mavrigian and republished with permission of CarTech Inc

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/engine-balancing-101-everything-you-need-to-know‎

The post Engine Balancing 101: Everything You Need To Know appeared first on Muscle Car DIY.

Measuring Piston Skirts

Prior to boring and/or honing cylinder bores, the pistons that are intended for installation must first be measured for skirt diameter to determine the required bore diameter adequate for piston-to-wall oil clearance. Piston diameter dictates the final bore diameter.

Measuring piston diameter is not determined at the ring area; rather, the measurement must be taken at the skirt, but only in the specific height location specified by the piston maker. For example, the piston maker may specify that the diameter measurement be taken at a point exactly .500 inch from the bottom of the skirt. Measuring at the specific point recommended by the piston maker is necessary, since pistons are not the same diameter from top to bottom, by design. A very slight “cam ground” or barrel-shape profile at the skirt area is designed to reduce friction and to promote piston stability, which in turn optimizes ring seal. Both the cylinder block bores and pistons (hypereutectic or forged) must be measured at room temperature approximately 68 degrees F, because metals expand and contract with temperature variations. The measured piston skirt diameter dictates the required cylinder bore diameter to achieve the piston maker’s specification for piston-to-bore clearance. Always measure skirt diameter at the point indicated by the piston maker.

Skirt diameter is measured using an outside micrometer. Considering the precise manufacturing techniques for today’s aftermarket performance pistons, you should be able to measure only one piston from the set and assume that all remaining pistons have the same diameter. However, it never hurts to measure each piston just to be safe. Most of today’s performance piston makers hold their tolerance to about .0005 inch at the gauge point.

Before final-honing cylinder bores, the piston skirt must be measured at the exact skirt height location specified by the piston maker.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/pistons-101-everything-you-need-to-know ‎‎

If pistons were sourced from an established manufacturer, such as JE, Wiseco, Ross, CP, Mahle, etc., it would be extremely rare to encounter a problem. Manufacturers such as JE normally hold to a very consistent tolerance of +/- .0005 inch, and even offer a “critical process” for custom piston orders held to even tighter tolerances.

Piston-to-wall clearance is specified by the piston maker. Hypereutectic pistons tend not to expand as much under operating temperature as forged pistons, so hyper pistons usually require a tighter piston-to-wall clearance. Always follow the piston-to-wall clearance that is recommended by the piston maker. As a general rule, given the same piston skirt measurement, a hypereutectic piston may require approximately .0015- to .0025-inch clearance, while a forged piston of the same size may require .0035 to .0055 inch for a naturally aspirated street application. Adding nitrous injection or forced induction may require an increased bore diameter of .0020 to .0035 inch for hyper pistons or .0045 to .0065 inch for forged pistons. Adding nitrous or forced induction may require an additional .001 to .002 inch of added clearance as opposed to naturally aspirated applications, depending on the piston maker’s specs. Again, follow the piston maker’s specifications for piston-to-wall clearance when the cylinder bores are being final-honed.

Although on the subject of skirts, some piston applications are available in an asymmetric design. This means that the skirt size on each side of the piston is different; a larger skirt area is on the piston’s major thrust side (exhaust side of the right bank and intake side of the left bank) and a smaller skirt is on the minor thrust side, where friction and load are minimal. This saves weight and reduces bearing wear.

Asymmetrical pistons feature a larger skirt area for the major thrust side and a smaller skirt for the minor thrust side. The wider skirt accommodates the high stresses of the piston as it is pushed against the major thrust side of the cylinder. The exhaust side is located on the right bank and intake side on the left bank. Using a smaller skirt on the minor thrust side saves weight. These JE pistons (shown) for the LS engine platform feature a forged side relief design, and it provides added clearance to the reluctor wheel in stroker applications. Asymmetric pistons are labeled for bank location and front orientation.

Checking Ring-to-Piston Fit

Never assume that the rings you have fit your pistons correctly. Refer to the piston maker’s specs and measure for ringside clearance and radial clearance. Insert a top ring into the top ring groove and use a feeler gauge to measure side clearance. With the ring seated against the floor of the groove, side clearance is the distance from the top surface of the ring to the roof of the groove. This is likely in the .001- to .002-inch range. Radial clearance, or back clearance, is the clearance behind the inside of the ring to the inside wall of the ring groove. This is likely in the .005-inch range. Perform this check prior to file fitting the rings to avoid wasting a bunch of time working on rings that don’t fit the grooves.

Modifying Domes

If domes are to be modified, a dedicated, adjustable piston vise is a necessity. This fixture allows mounting the piston securely and is adjustable for valve angle. Before attempting to mill piston domes, pay particular attention to existing dome thickness, specifically the thinnest section of the dome. Depending on the piston material, the thinnest allowable area might be .150 or .200 inch, as examples. If in doubt, check with the piston maker for advice on this. If an area of the dome is too thin, the dome can sag under heat and pressure and potentially break through.

Checking piston ring side clearance with a feeler gauge. Follow the specification provided by the piston maker. Side clearance is usually about .001 to .002 inch.

Ring back clearance is checked with the ring installed and pushed back to the inner groove wall. The distance from the face of the ring and the outer diameter of the piston surface is measured to determine back clearance. This is usually about .005 inch.

Before milling a piston dome, consider the thinnest section first to determine how much, if any, can safely be removed without compromising dome strength. The black mark on the cross-section indicates the thinnest section of this piston dome.

Depending on the combination of cylinder head design, piston design, piston compression distance, crank stroke, rod length, head gasket thickness, block deck height, and valve-to-piston clearance possibly due to camshaft profile and rocker arm ratio, it’s possible to run into clearance issues. First, consider clearance between the piston dome and head, and between piston dome and the spark plug. The suggested absolute minimum clearance (with the head gasket in place and fully torqued) between the piston and head and/or spark plug is .040 to .050 inch for steel connecting rods and .055 to .060 inch for aluminum connecting rods (due to potentially greater expansion rate of alloy rods).

If the piston domes require modification by fly-cutting or making valve pockets deeper or larger, a dedicated piston pin vise allows the piston to be secured in the proper location and angle for the milling machine. This piston is being cut to obtain more valve radial clearance at Ross Racing Engines in Niles, Ohio.

A common method of checking piston dome clearance relative to the head and spark plug is to apply modeling clay to a dry, clean piston dome; coat the chamber lightly with a thin oil to prevent the clay from sticking to the chamber. With a head gasket and head installed and fully torqued, but without pushrods, slowly rotate the crank to allow the piston to reach TDC. If you feel a dead stop, the piston may be in contact with the head, so don’t try to force crank rotation. Remove the head and inspect and measure the clay for contact. If you did not experience a positive stop and rotation to TDC was achieved, examine and measure the clay areas that were compressed for thickness by carefully slicing a cross-section of the clay with a razor and carefully measuring thickness with a small machinist’s ruler or depth caliper. If you find tight spots that feature less than the recommended clearance, remove the clay and mark those areas on the dome.

In preparation for piston dome machining, the combustion chambers are profiled digitally to obtain the required piston dimensions.

Reapply clay, reinstall the head, this time with a spark plug installed, and repeat the process to determine spark plug clearance.

Prior to dome modifications, the initial dome heights are measured with a digital height gauge.

The piston dome is receiving a custom dome profile on a CNC lathe.

Examine the point between valve pockets. If this is very sharp, use a light abrasive to slightly soften this to minimize the potential for a hot spot that could contribute to detonation/ pre-ignition.

The sharp corner between valve pockets was relieved on this piston, eliminating a potential hotspot.

Checking Valve-to-Piston Clearance

Check valve-to-piston clearance in both the vertical and radial planes. In the vertical plane, you’re checking for the clearance between the valve face and the valve pocket. In the radial plane, you’re checking for the radial clearance of the valve head to the radius of the valve pocket in the piston dome.

Although clay checking, as described earlier, is a common approach, this method poses variables such as the compression and possible spring-back of the clay, a potential separation of the clay from the piston, and clay sticking to the valve.

Using a degree wheel on the crank snout to check intake valve to piston vertical clearance, rotate the crank at least twice and then bring that piston to 10 degrees ATDC on the intake stroke, generally a position where the valve is closest to the piston. Be aware that two crank rotations are required to rotate the camshaft once.

Install a light checking valve- spring onto the valve being checked. When checking valve-to-piston clearance, a solid lifter is required, because a hydraulic lifter may bleed down and provide a false reading. If the engine will be fitted with hydraulic lifters, locate a solid lifter of the same pushrod cup-to-tip length (a spare hydraulic lifter with the plunger tack welded to prevent plunging works).

Clay was applied to both intake and exhaust valve reliefs. The piston dome must be dry prior to applying the clay to ensure that it sticks to the dome. A light coat of thin oil is applied to the combustion chamber and valve faces to prevent the clay from sticking to those surfaces.

With clay applied to the piston valve pocket, the crank was rotated twice to rotate the cam one full turn. With the head removed, you see the valve impression in the clay. After cutting the clay with a razor, you see a cross-section of the clay thickness, which is then measured. This intake valve shows about .200-inch valve-to-piston clearance. Minimum suggested intake valve clearance is .080 inch, while minimum exhaust valve clearance is .100 inch.

A dial caliper’s depth tip can measure the clay thickness, or the clay section that was removed can be carefully measured with the caliper jaws. Due to the compressibility and potential spring-back of the clay, the clay method offers a rough estimate of clearance.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/pistons-101-everything-you-need-to-know ‎‎

With a lifter, pushrod, rocker, and light checking valvespring installed, adjust valve lash and set up a dial indicator onto the retainer and preload the gauge dial with enough travel to accommodate valve movement, and zero the gauge. With your finger or a small screwdriver, push the valve down until it touches the piston. The difference between the zero reference and piston contact indicates how much clearance the valve has to the piston. Generally speaking, for a naturally aspirated application, a minimum of about .080- to .090-inch intake clearance should be adequate. Follow the same procedure to check exhaust valve clearance, but with the piston located 10 degrees BTDC on the exhaust stroke. A generally accepted exhaust clearance is .100 to .110 inch.

With a light checking valvespring installed in this intake valve, the crank is rotated to bring the piston 10 degrees ATDC. A dial indicator is set up, contacting the spring retainer. The dial is set to zero.

To check valve-to-piston valve relief radial clearance, instead of using clay, a spare valve can be cut and ground to a point to serve as a center-of-valve reference.

For a blown (forced induction) application, valve-to-piston clearances need to be a bit greater, approximately .125 inch at the intake valve and about .175 inch at the exhaust valve.

The spring is compressed until the valve contacts the piston. The gauge needle turns in a counterclockwise direction, showing this valve-to-piston clearance at .087 inch.

Measure the diameter of the valve head. After you measure the radius distance from the center mark, you factor one-half of the valve head diameter.

With the piston at 10 degrees ATDC to check the intake valve, the modified spare valve is inserted upside-down with the pointed end facing the piston. Using hand pressure, the pointed valvestem places a mark on the dome that indicates the centerline of the valve.

Instead of checking with clay, a more accurate method of checking radial clearance is to remove a valve and grab a spark/junk valve of the same stem diameter. On a lathe, cut the tip off and grind it to a point. Color the piston dome valve pocket center area with a marker. Install the head gasket and head. Rotate the crank to bring the piston to TDC or about 10 degrees BTDC. Insert the ground, pointed valve upside-down into the valveguide and gently contact the piston, applying enough hand pressure to place a mark on the piston that provides a valve centerline mark. Remove the head.

Measure the diameter of the head of the valve that is to be final installed. Set your caliper to half of the valve head diameter. For example, if the valve head measures 2.080 inches in diameter, set the caliper at 1.040 inches. Place one end of the caliper jaw at the marked center valve mark and sweep across the edge of the valve relief to determine how much radial clearance you have. A suggested minimum clearance is about .085 to .100 inch.

If clearance is an issue, consider using a thicker head gasket (which of course decreases compression ratio). An alternative is to mill the piston dome at the contact area(s). This is done on a dedicated piston vise on a milling machine.

As noted earlier, be aware of existing dome thickness to avoid weakening the dome. Depending on the clearance area, the valve pockets may be cut deeper and/or larger in diameter, and/or the flat area of the dome can be milled to increase clearance.

After removing the head, measure the distance from the center point to the edge of the valve relief. Using the radius of the already-measured valve head, you can determine how much radial clearance you have.

If piston-to-head clearance is an issue and the pistons feature a center-domed profile with no valve pockets (such as found on a vintage flathead Ford, for example), the domes may be reduced on a CNC lathe. The pistons are first measured for dome height and profile, and the cylinder head chambers are digitally profiled for shape. The data is then programmed and fed to a CNC lathe that can cut the dome to precisely the height and shape required for clearance.

If more than about 4 grams of material is removed from the piston domes, the crankshaft should be rebalanced, considering the change of piston weight. For high-RPM racing applications, any change in piston weight should require the crank to be rebalanced.

File Fitting Rings

When over-boring cylinders to repair or to increase bore displacement, it’s not uncommon for the supplied ring set to include top and second rings that are slightly larger in diameter, to require custom file fitting to achieve the desired end gaps. This is not a compromise on the part of the ring maker. Rather, this allows the builder to establish the precise gaps recommended by the piston maker, based on how the engine is to be built and used.

A rule of thumb for ring end gap is .004 inch per inch of bore diameter. However, it is absolutely essential to follow the piston maker’s specifications for ring end gap, as the recommendation may increase to as much as .006 inch per inch of bore diameter or more. The piston maker already knows how the specific piston material and construction is expected to grow in diameter during engine operation, so follow their specifications.

End gap is the clearance distance between the two ends of a ring when installed in the bore. Factors including forced induction (supercharging or turbocharging), the use of nitrous injection, and the operating environment (street, endurance racing, drag racing, etc.) all play a part in determining the optimum top and second ring end gaps.

File fitting top and second rings involves removing material from the ends with a fine file or, ideally, with a dedicated piston ring filing machine.

Rather than assuming that each cylinder requires the same final sizing, it’s recommended to file-fit each ring for the specific cylinder. For example, instead of using cylinder number-1 as the reference to file-fit all rings, you should file-fit the top and second ring for cylinder 1, then file fit rings for cylinder 2, etc., keeping all rings organized for cylinder location. Slight variances in cylinder wall dimensions are possible, so for achieving optimal end gaps, custom fit rings to each cylinder.

Before file fitting rings, check each ring to its intended piston to verify proper ring groove side clearance and radial depth to make sure that the rings are compatible with the pistons.

When you insert a ring into the cylinder for end gap checking, the ring must be set at an equal depth along the entire cylinder bore diameter. Using a ring-squaring tool makes this easy and quick. Insert the ring near the top of the bore and insert the squaring tool, which pushes the ring evenly down into the bore. Remove the tool and you’re ready to check gap.

When checking ring fit to the cylinder, a feeler gauge is used to determine end gap. The ring must be squarely installed at the same depth around the entire perimeter of the ring relative to the deck. If the rings require file fitting, the end gap should be checked in stages between filing to avoid creating a too-large end gap.

Side clearance is the vertical clearance of the ring relative to the upper or lower base of the ring groove. With the ring placed into its groove, push the ring down until the bottom of the ring is flush with the bottom land of the ring groove, then measure the clearance between the top ring surface and the roof of the ring groove with a feeler gauge. Side clearance should be .001 to .002 inch. Radial clearance is the inward/ outward clearance of the ring within the groove. This is the difference between the outer diameter surface of the ring to the inner diameter surface of the ring, relative to the depth of the ring groove. With the ring pushed fully inward until the back of the ring seats against the wall of the groove, measure the distance from the face of the ring to the outer edge of the groove. Radial clearance should be approximately .005 inch.

With the cylinder bores wiped clean, compress the number-1 cylinder’s top ring carefully by hand and insert it into the bore. Make sure that the ring is properly oriented. If a dot appears on one side, the side with the dot should face upward. Insert the ring about 1/2 to 1 inch into the bore, with the ring squared so that it is at the same depth along the entire circumference, relative to the deck. You can use a caliper or depth gauge or a small ruler to adjust this, or an easier and quicker way is to use a ring-squaring tool that automatically pushes the ring squarely into the bore. Check the existing end gap. In the case of file-to-fit rings, you may find zero gap or even an overlapping gap.

Top and second rings that require file fitting may be filed with a small, flat, fine file, but a dedicated ring filer makes the job easier and more precise. Each end of the gap must be filed by the same amount. The filer features a diamond abrasive wheel that provides a nice square cut. By applying slight hand pressure to place the ring end against the wheel, count the number of handle rotations during each filing. After correctly filing a few rings, you get an idea of how many turns are needed to achieve your desired end gap. This makes filing the remaining rings a bit quicker. Always file by a few turns, clean the ring and check the gap in the cylinder. Filing in stages helps to prevent accidental overfiling.

Remove the ring and file the ends, removing an equal amount of material from each end. Then insert the ring again and measure end gap using a feeler gauge. Perform the filing in small increments to avoid ending up with a gap that is too large. When the proper gap is achieved, remove the ring and carefully remove any burrs from the filed ends, using a small flat fine file. Wash the ring and store it on a clean workbench next to your number-1 cylinder’s pistons and rod. Repeat this process for all top rings, and for all second rings, cylinder by cylinder, and keep all rings organized for cylinder location. Remember to orient all top and second rings properly, because, depending on the ring profile, they may have a dedicated top and bottom surface. If the top and/or second ring have a small dot mark, the mark must face upward when installed.

If the piston wrist pin bore is raised due to the required compression distance, the pin bore can intersect the oil ring groove. In these cases, the piston maker provides a set of support rings that are installed to the floor of the oil ring groove, providing oil ring support at the voids at the top of the pin bore. The support rail features a small bump dot, which must be oriented at the center of the pin bore. This small protrusion prevents the support rail from accidentally rotating, keeping its end gap from moving over one of the pin bore voids.

The supplied oil ring rails should provide a minimum of the specified end gap, so you should not need to file any of the oil ring rails. By the same token, if your pistons require support rails (due to a short piston compression distance where the wrist pin bore intersects with the oil ring groove), there is no need to perform any file fitting for the support rail. Its end gap is not critical; it only serves to provide oil ring package support over each end of the wrist pin bore and serves no sealing purpose.

Written by Mike Mavrigian and republished with permission of CarTech Inc

LEARN MORE ABOUT THIS BOOK!

If you liked this article you will love the full book!

LEARN MORE ABOUT THIS BOOK HERE

The post Pistons 101: Everything You Need To Know appeared first on Muscle Car DIY.

Using an outside micrometer, carefully measure the crankshaft’s main journal diameters and record the measurements. Set up a bore gauge to this measurement and adjust the gauge dial to the zero mark.

Install the upper and lower main bearings and install the main caps; torque the main cap fasteners to specification. Insert the bore gauge into each installed main bearing.

After a bore gauge is set up to match the crank main journal diameter, the gauge is inserted into the installed main bearing to determine the bearing I.D. relative to the crank main journal.

The difference from the gauge dial’s zero mark indicates how much larger or smaller the main bearing is relative to the crank journal. For instance, if the gauge reads .002 inch greater than the crank journal diameter, you have an oil clearance of .002 inch.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/uncategorized/how-to-prepare-and-grind-a-crankshaft‎

If a check using standard thickness bearings reveals an inadequate oil clearance, performance bearing makers offer bearings in “X” size, with the “X” indicating that the bearing shell is .001 inch thinner, which provides an additional .001 inch clearance. Builders often mix and match standard with X bearings to obtain the exact oil clearance desired. For instance, if you need to pick up an extra .001 inch, you could use one standard bearing and one X bearing on the same journal. Each bearing half in an X bearing set will provide .001 inch additional clearance. Generally, when mixing thicknesses, the thicker bearing insert is installed as the lower bearing (for example: standard insert as the upper and X insert as the lower). One example is that a standard bearing insert for a small block Chevy measures .095 inch thick, while an X bearing measures .094 inch thick.

An upper H series main bearing insert from MAHLE Clevite. Stamped “STD” to indicate standard thickness. This small block Chevy upper bearing thickness measures .095 inch.

Measure crankshaft main journals with a calibrated micrometer. Make sure that the journal is clean before measuring, with no grease or oils present. Measure each rod journal as well. Make sure that the micrometer anvils are squared up and flush to the journal surfaces.

Rod Bearings

Using an outside micrometer, measure the crankshaft’s rod journal diameters. Record this measurement. Remove the rod’s cap and install the upper and lower rod bearings, and reinstall the rod cap; torque the rod bolts to specification. To stabilize the rod and to protect the rod from damage, place the rod big end into a dedicated rod vise while torquing the rod bolts. Set up a bore gauge to match the rod journal diameter, then zero the gauge dial. Insert the bore gauge into the rod big end bearing and note how the reading differs from the rod journal diameter. The difference indicates how much greater or lesser the bearing bore diameter is relative to the rod journal diameter. For instance, if the bearing measurement reads .0024 inch greater than the journal diameter, you have an oil clearance of .0024 inch. When using the bore gauge, gently rock the bore gauge back and forth to obtain an accurate reading. The point at which the gauge needle moves to maximum and then moves to minimum, the minimum point represents the true reading.

When removing or installing rod caps on the workbench, it’s best to use a dedicated rod vise to secure and protect the rod. These vises feature composite material on the jaws to prevent nicking or gouging the rod big ends.

When measuring main or rod bearing inside diameters, keep the bore gauge anvil and plunger away from the bearing parting lines, because the area adjacent to the parting lines is slightly tapered to promote oil ramping. Also avoid contacting any oil holes or grooves in the bearings.

Cam Bearings

Generally, in an overhead valve engine, cam bearings are installed and then the camshaft is test fitted. If the cam rotates easily on its bearings, cam to bearing clearance is considered acceptable. However, if you want to know what the oil clearance actually is, use a micrometer to measure the camshaft’s journals. Set up a bore gauge to match the journal diameter, then zero the gauge dial. Insert the bore gauge into the installed cam bearings and observe how the bearing inside diameter differs from the cam journal diameter. For example, if the bearing inside diameter reads .0018 inch greater than the cam journal diameter, you have an oil clearance of .0018 inch. As with main or rod bearings, be careful to avoid dropping the gauge anvil and plunger into the cam bearing oil hole.

With rod bearings installed and the rod bolts fully tightened to spec, a snap gauge or bore gauge can be used to measure installed bearing I.D.

When test fitting the camshaft, it must rotate freely by hand. If it’s difficult to turn or if you feel resistance in one spot, the cam bearings likely require hand scraping using a sharp cam bearing scraper.

If the camshaft shows resistance to rotating by hand, remove the cam and inspect each cam bearing. You should be able to see slight wear marks on the bearing(s). Using a sharp, dedicated cam bearing scraper tool, the area of the bearing that appears to be tight can be carefully relieved. Reinsert the cam and verify that you have smooth rotation.

Cam Thrust

A flat tappet camshaft features slightly tapered lobes. A slight crown on the face of the flat tappet lifters allows the lifters to rotate to prevent excess wear. The taper profile on the lobes, a slight offset of the lifters’ bores relative to the cam lobes, and the action of the distributor gear all tend to “pull” the cam rearward, so cam endplay isn’t as critical.

However, when you’re dealing with a roller camshaft, the lobes are straight, with no taper. The roller lifters need to be maintained on center with the lobes, so you need to avoid excessive cam walk, but you still need a bit of endplay to prevent a too tight fore/aft fit. A retainer plate at the front of the block may be used, or the addition of a roller bearing thrust button may be required to act as a positive stop between the cam nose and timing cover. The thrust button can be shimmed to adjust endplay. Comp Cams, for example, recommends roller cam endplay at .004 to .010 inch. Excessive endplay can cause roller lifters to run at the edges of the lobes, and if the cam features a distributor drive gear, too much endplay can result in premature gear wear and timing fluctuations.

For performance applications, some builders prefer to add a thrust button to reduce cam walk, even to a flat tappet cam, to reduce timing fluctuations.

Piston to Wall Clearance

When reconditioning a block or when prepping a new block, cylinders are bored (if necessary) and final honed to obtain the desired bore diameter and piston to wall clearance. The piston skirt must be measured with a micrometer, at the specific height specified by the piston maker. When piston skirt diameter is known, the cylinders are honed to provide the needed wall clearance. Always refer to the piston maker’s clearance recommendations, which is based not only on the piston design and material but the intended application as well. For instance, a street naturally aspirated application might call for .004 inch clearance, while a forced induction and/or nitrous application may call for slightly greater clearance.

If a flat tappet cam is to be used, use a dial indicator to check cam thrust. In this example, you have cam thrust at .004 inch.

Prior to final honing the cylinder bores, measure the piston skirt using a micrometer. Measuring must be performed exactly at the skirt height specified by the piston maker.

With a pair of rods installed to a common crank rod journal, use a feeler gauge to determine rod sideplay.

A cylinder bore gauge is carefully adjusted to the measured piston diameter and inserted into the cylinder bore to determine the difference, which indicates piston to wall clearance.

The type and construction of the piston affects the desired piston to wall clearance. For instance, high silica hypereutectic pistons do not expand as much under operating temperature as forged pistons. As a result, hyper pistons usually require a tighter wall clearance when compared to forged pistons.

Generally speaking, a hypereutectic piston may require approximately .0015 to .0025 inch clearance, while a forged piston of the same diameter may require .004 inch or so for a naturally aspirated street application. If the application calls for forced induction or nitrous injection, an additional .001 to .002 inch or so of wall clearance may be required. As I’ve mentioned repeatedly, always refer to the piston maker’s recommendations for wall clearance.

Rod Sideplay

Connecting rod sideplay refers to the distance that each rod big end can move front to rear on its journal. With the crankshaft installed in the block, insert the rod bearings and install the rods to the crank. Make sure that each rod is oriented properly on its journal, with the chamfered side of the big end facing the crank fillet. In an engine that features a pair of rods on a common journal, both rods must be installed to each journal. Using a feeler gauge, push the rod big ends away from each other by hand and insert a feeler gauge between the rod big ends. Refer to the engine specifications for rod sideplay, but it should generally be in the range of .010 to .019 inch.

Lifter Bore

Measure the O.D. of a lifter body. Using a bore gauge, measure the inside diameter of the lifter bore. Always refer to the engine specifications for recommended oil clearance. Generally, lifter to lifter bore clearance is in the .0015 inch or slightly greater range. Regardless of the spec, each lifter should easily drop into its bore. If lifter bores must be enlarged, it can be done either by honing or machining with a cutter. In terms of obtaining the best surface finish for oil retention, some lifter makers may recommend honing or cutting.

Before checking lifter bore clearance, make sure that the lifters are clean and free of any particles. The lifter bores must be clean as well. Measure the lifter body diameter with a micrometer.

Adjust a lifter bore gauge to the lifter diameter and insert into the lifter bore to determine lifter to bore oil clearance.

Lifters should drop into their bores easily. Any resistance indicates a too tight lifter bore.

With the block secured upside down on a stand, lay the upper main bearings into their saddles and place the crankshaft. When checking only for crank counterweight clearance to the block, there’s no need to install the main caps.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/uncategorized/how-to-prepare-and-grind-a-crankshaft‎

Crank to Block Clearance

When using a crankshaft that has an extended stroke, you must check crankshaft counterweight clearance to the block, primarily at the lower web and oil pan rail areas. With the block positioned upside down on a stand, install the upper main bearings in the block bearing saddles. Apply a thin coat of oil or lube to the bearing faces. Lay the crankshaft onto the upper bearings. Carefully rotate the crankshaft, noting clearance between the counterweights and the block. To accommodate any dynamic and thermal expansion issues in the running engine, minimum clearance should be approximately .080 inch or more. Examine clearance at each counterweight as you rotate the crank a full 360 degrees. Mark the block with a marker pen at any tight clearance areas. If any clearance issues are found, remove the crank

With the area of interference marked, a die grinder is used to create a relief by the estimated depth, which then must be rechecked with the crank and rod in place.

and the upper bearings, and use a die grinder to relieve material in the appropriate areas. After cleaning the block, install the upper bearings and crankshaft and double-check to verify clearances.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.musclecardiy.com/uncategorized/how-to-prepare-and-grind-a-crankshaft‎

Rod to Block Clearance

As with potential crankshaft to block issues, if you’re using a stroker crank, you must check rod big end to block clearances. With the block upside down on a stand, install the upper main bearings and apply a thin coat of lube to the bearing faces. Install the crankshaft, install the lower main bearings to the main caps, lube the lower bearings, and install the main caps. Assuming the cylinder bores have already been bored and honed to size for your pistons, assemble rods to pistons and arrange the rods/pistons on a clean workbench. There’s no need to install piston rings at this time. Remove the rod caps from each rod, keeping all rods and their caps organized. Install upper and lower rod bearings to the rods and caps and apply a thin coat of lube to the exposed bearing faces. Apply a thin coat of oil to the cylinder walls.

During test fitting of this engine, the rod big ends contacted the inner edge of the oil pan rails. Areas of concern were marked for grinding.

Perform this check one cylinder at a time. Cylinder by cylinder, starting with cylinder number 1, install a rod and piston assembly. Snug the rod bolts so that the cap is fully seated. There’s no need to fully torque the rod bolts to spec at this time.

Carefully and slowly rotate the crank a full 360 degrees, closely watching the rod big end for clearance at the block webs and pan rails. If you find an obstruction or inadequate clearance, mark the block with a pen.

Remove that rod and piston and continue the process with remaining bore locations, marking any clearance issues as you go.

Minimum rod big end to the block should be at least .080 inch or more. If clearancing is required, disassemble to a bare block, grind clearance as needed, wash the block, and reinstall the crank and rods to verify your clearances.

Aftermarket performance blocks commonly provide a rod clearance notch to accommodate common stroke increases. Depending on the stroke of the crank, this may or may not clear your combination.

During test fitting, the rod bolts interfered with the block pan rail inboard area.

After grinding a relief, the fit was again checked to verify adequate rod bolt clearance.

When using an increased stroke crankshaft, check for possible rod big end clearance issues with the camshaft. This shot shows a rod shoulder that seems close to the cam tunnel, but further checking verified that clearance was not an issue. This is the reason that many aftermarket block makers offer block versions with raised cam tunnels.

Piston Ring Gap

After the cylinders have been final honed to size, check the piston ring end gaps in each cylinder. In some cases, you may be using file to fit rings. Organize the rings on a clean workbench, grouping all top rings and second rings.

When checking installed ring end gap, the ring must be squared in the bore at an equal depth along the entire circumference of the ring. A ring-squaring tool such as the one shown here makes this easy. Simply insert the ring, place the tool into the bore, and press down until the tool base is flush to the deck. This type of squaring tool is adjustable for bore diameter.

If top and second piston rings must be filed to fit the cylinder bore, a small, flat, fine file may be used. A bench-mounted ring filer makes the job easier and quicker. Gently apply pressure to force the ring end into the diamond wheel, keeping the ring flat on the tool base and the end square to the abrasive wheel. File the same amount from each end of the ring’s gap in small increments, checking installed gap as you go. Until you become accustomed to how much material is removed per stroke of the filer, plan on performing this task several times to creep up on the desired gap. After the ring has been filed to fit, use a small, flat, fine file to deburr the filed edges.

With the cylinder walls clean, carefully insert a top ring into the cylinder by hand. Using a ring squaring tool, push the ring down into the cylinder. The ring must be “squared,” meaning that it must be placed at the same depth around the entire circumference of the ring. The ring should be placed approximately 1/2 to 1 inch below deck.
Using a feeler gauge, measure the ring end gap. Refer to your piston spec sheet for recommended gap for top and second rings. If the ring has no gap, it must be filed to fit. Remove the ring and, using a fine file or a dedicated ring filer, file an equal amount from each end of the gap, clean the ring, and reinsert into the cylinder and measure the gap. Perform this in gradual steps to avoid removing too much ring material. After the ring is properly gapped, use a fine file to carefully remove any sharp edges and burrs from the filed ends. Clean the ring and place it on a clean workbench, marked for the specific cylinder where the check was performed. Continue this for all remaining top rings, then repeat the process for all second rings. Keep all rings organized on a per cylinder location basis.

With the ring squared in the bore, use a feeler gauge to measure the ring end gap.

With the dial indicator mounted rigidly, the gauge plunger is set with a slight preload of about .050 inch. The crank is pushed fully in one direction, and the dial is adjusted to the zero mark. As the crank is pushed in the opposite direction, the amount of endplay is revealed on the gauge. Repeat this check several times to verify an accurate measurement.

Here a dial indicator is set up to check crank endplay. If the block is aluminum, placing the magnetic base to the front of the main cap suffices.

Crank Thrust

Install the upper main bearings and apply a thin coat of lube to the bearing faces. Make sure that the crank is clean, with any residue or shipping surface grease cleaned from all journals. Install the crankshaft to the upper bearings. Install the lower main bearings to the main caps, apply lube to the bearing faces and install the main caps, fully tightening all main cap fasteners to specification. As you tighten the main caps in steps, start by tightening to about 10 to 15 ft lbs, then rotate the crank and gently knock it forward and rearward with a plastic or rubber mallet. Continue tightening to about 30 to 35 ft lbs and rotate again. Continue until all main caps are fully torqued to specification. Place a magnetic base dial indicator stand onto the face of the block, or to the face of the front main cap if you’re dealing with an aluminum block. Adjust the stand so that the dial indicator gauge plunger contacts the front of the crank, at either the end of the snout or at the front of the first counterweight.

If the block is cast iron, the dial indicator’s magnetic base may be placed against any convenient flat surface. Make sure that the magnetic base is rigid and does not rock or wiggle.

Using a clean pry tool such as a long straight end screwdriver, pry the crank fully rearward, placing the pry tool between a counterweight and a cap; be careful not to contact any journal surface. With the crank moved fully rearward, adjust the dial indicator to place about .050 inch or so preload against the crank, then zero the gauge.

Thrust bearings feature front and rear bearing shoulders to provide a bearing buffer that locates the crank’s fore/aft clearance. If crank thrust is too tight, the thrust faces may be slightly relieved by laying the thrust surface against a clean sheet of emery cloth on a perfectly flat hard surface and rubbing the thrust surface against the abrasive.

Next, carefully pry the crank fully forward, and note how far the crank has moved on the dial indicator gauge. Repeat this measurement several times to make sure that you’re obtaining an accurate and repeatable measurement. This movement distance represents the crank’s endplay, or thrust movement. Refer to your engine’s crank endplay specification. Generally, crank endplay should be in the range of .005 to .008 inch, but don’t assume. Always refer to the specs. Depending on thrust bearing style, if endplay is too tight, you may be able to shave a bit of material from the thrust bearing thrust faces by laying a new sheet of emery cloth onto a flat, hard surface such as glass or granite and rubbing the thrust face against the emery cloth. If you do need to shave the thrust faces, measure the existing thrust face width with a caliper or micrometer and record the measurement. Constantly remeasure as you remove material to avoid removing too much. If crank endplay is excessive, again depending on the thrust bearing style, you may be able to order a thrust bearing with a thicker thrust wall.

Applying clay to the piston requires cleaning the piston dome so that it’s completely dry for the clay to stick. The valve faces need to be lightly oiled to prevent the clay from sticking to the valves.

Valve to Piston Clearance

As I discussed prior, valve to piston clearance must be checked in both the vertical and radial planes. In the vertical plane, you’re checking for the clearance between the valve face and the valve pocket. In the radial plane, you’re checking for the radial clearance of the valve head to the radius of the valve pocket in the piston dome. Refer to Chapter 8 for the procedure in checking these clearances. One method involves clay checking, where modeling clay is applied to the piston dome and the crank is rotated to allow the cam, lifters, pushrods, rockers, and valves to run through a complete cycle, providing witness impressions that allow you to measure valve clearance by cutting a cross-section of the clay and measuring its thickness. Another method involves using a dial indicator to measure valve movement relative to the piston dome.

The clay is sectioned with a razor and measured for thickness. Using clay is helpful but may not be extremely accurate, considering potential springback of the compressed clay, but it gets you in the ballpark.

A rule of thumb is to obtain approximately .080 to .090 inch of vertical intake valve to piston clearance and about .100 to .110 inch of vertical clearance for exhaust valves. A forced induction application generally calls for greater clearance, in the range of .125 inch for intake valves and .175 inch for exhaust valves. Valve radial clearance should be in the range of .085 to .100 inch.

To create a witness mark onto the piston that indicates the valve’s centerline, a spare valvestem tip is ground to a point.

The valve head is measured for diameter.

The radius measured from the valve’s center point.

A point machined spare valve is inserted to place a reference center mark onto the piston.

Here an exhaust valve to piston clearance is being checked. With a light checking valvespring installed, and with the piston moved to 10 degrees BTDC, where the valve should be closest to the piston, position a dial indicator contacting the top of the retainer. Preload the gauge by about .150 to .200 inch and zero the gauge.

By pushing the retainer down until the valve touches the piston, note the sweep movement of the gauge needle. In this example, you note an exhaust valve clearance of .113 inch.

Written by Mike Mavrigian and republished with permission of CarTech Inc

LEARN MORE ABOUT THIS BOOK!

If you liked this article you will love the full book!

LEARN MORE ABOUT THIS BOOK HERE

The post How to Check for Clearance When Rebuilding an Engine appeared first on Muscle Car DIY.

Crankshafts

Nailheads

The Nailhead uses four different forged-steel cranks. These forged-steel cranks are used in the 1953–1956 264/322 and 364, 1959–1963 401 and 425, and 1964–1966 401 and 425. The two different 401- and 425-ci cranks were a result of the transmission converter hole on the back. The Dynaflow transmission, used until 1963, had a larger pilot hole in the end of the crank than the 1964–1966 crankshaft that used the ST300 and ST400 transmission. Nailhead specialist Russell Martin, sells an adapter bushing that fits in the rear of a 1957–1963 crank. He also offers a dual-pattern Nailhead starter. With this adapter and a 1964–1966 flexplate, the ST300 and ST400 transmissions can be installed on all 1957–1963 engines. However, the 1953–1956 engines use the same crankshafts except the factory stick shift, which had a smaller hole for a pilot bushing. Small, lightweight mini gear reduction starters are available from nailheadbuick.com and Tom Telesco. The Dynaflow starter has about a 1/2-inch longer snout so the shorter 1964–1966 starter or special mini starter must be used. The 1961–1966 block accepts the 1964–1966 starter as is, but the 1957–1960 block has a different starter bolt pattern.

This is the Thomas Telesco gear-reduction starter for the 1964–1966 Nailheads.

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/pistons-rods-cranks-oh-my-how-to-build-horsepower-with-a-buick-engine/

Small-Block 350

The smaller of the Buick powerhouses, the 350, does benefit from the same aftermarket support as its big brothers. The 350 had but one crankshaft, a cast nodular-iron unit. Fortunately, the stock crank is strong enough to support well over 500 hp. The 3.85-inch stroke crank will handle this magnitude of power, but the oiling system must be modified and the bearings need to be nice and tight. For power-added motors, such as turbos and superchargers, the stock crank is fine for engines up to 600 hp. If you plan on developing more than 500 hp, a custom crankshaft is required. Although expensive, the typical $2,000 price is cheap when you look at the overall price of building an extreme performance engine. Supercharged Buick 350 engines with stock blocks have been dyno’d at over 1,000 hp, so it certainly is capable of producing megapower as long as the right components are used.

There are aftermarket options available. This ATI Super Damper bolts onto any Buick 350, but it comes with a caveat. The externally balanced version requires the factory pulleys to be moved out from the engine about 1 inch because the crank snout was built long to clear the timing cover. This can be altered with some machining.

One drawback of the 350 is that the engine is built so tight, and there is literally no extra space between the rods and camshaft for any additional stroke. As a result, the cam must be installed before the crank; otherwise the crank and rods have to be rotated during the cam installation. By installing a custom-ground crank and custom pistons, you can increase displacement by a few ci, but the expense does not justify the performance benefits.

Big Blocks

The 400/430/455 crankshaft is also made from cast nodular iron, but these cranks easily support up to about 800 hp. For engines spooling more than 800 hp, there are aftermarket alternatives. All of the big blocks use the same 3.9-inch-stroke crank. The late-1970 and later cranks were cast without the telltale N, so don’t let this confuse you; it is assuredly a nodular-iron unit.

The stock crankshaft has very large 3.25-inch main journals because these large main journals added critical strength to the thin block. In most applications, the stock crank is more than enough to provide a solid, dependable base for the rotating assembly, as long as it is properly prepped and oiled. When using large amounts of nitrous (200-hp shot or more) or building extreme-output race engines, a custom forged-steel or steel-billet crankshaft is necessary. The stock crank cannot handle the hit of a 200-hp nitrous shot for long. It might work a few times, but it will eventually break, and then every single part on that engine will be unusable. You can build a custom billet crank for about $2,500, but this process often takes 6 to 10 months.

A micrometer, like this one, is the best bet when measuring clearances. This 350 crank was turned 0.010 inch to get perfectly concentric journals.

This 455 steel stroker crank has the full treatment with chamfered oiling holes, which increases oiling to the rods and main bearings.

Buick engines were externally balanced from the factory. This SFI-approved harmonic balancer from TA Performance should fit the bill for your Buick. If the stock balancer’s rubber insert is cracked, missing pieces, or squished out of the groove, it needs to be replaced. A defective balancer’s poor harmonics can rattle an engine apart. If the two pieces separate, there will be a lot of damage.

For those who subscribe to the gearhead adage, “there’s no replacement for displacement,” TA Performance’s 455 stroker kits are a good option. The 494-ci and 523-ci stroker kits offer more displacement for extreme performance. The TA cranks feature 4.150-inch stroke and a 2.0-inch crank-pin diameter. Each stroker crank is custom ground, precision indexed, and magnafluxed. In addition, each crank has chamfered oil holes and is micropolished for superior oiling.

V-6 Turbo

There are two types of 3.8-liter V-6 turbo crankshafts: the nodular iron crankshaft used in the turbo engines, and the standard 3.8-liter crankshaft. The nodular turbo crankshaft features a rolled radius on the main and rod bearings that adds concentricity and uniformity, which increases load distribution through the journals. This also adds a good deal of strength to the crankshaft and reduces stress risers, which can cause catastrophic failure. All 1978–1987 turbo 3.8-liter crankshafts are nodular iron with rolled radii. The standard 3.8-liter cranks have rolled fillets on the main bearings only, and this crank will not survive in a turbo engine.

This V-6 turbo crank from TA Performance supports the performance level of about any Buick engine.

For the V-6 turbo, this lightweight GM balancer is the ticket.

Main Seals

The Nailheads, the 350, and the big blocks used a factory rope seal, which originally sealed the crankshafts. But these seals were difficult to install and should be replaced with neoprene seals. There are, of course, a couple of techniques to make it easier.

The rear main seal was originally a rope seal. These types of seals leak constantly and are a nightmare to install. Replacing it with a neoprene seal is a simple conversion but does require a little preparation.

The groove for the seal should be modified with three divots in the block and in the main cap. This keeps the seal from rotating in place. The grooves should also get a little squirt of silicone. The silicone seals the perimeter of the seal and keeps oil in the crankcase where it belongs. The neoprene seal comes in two halves. Each half should be installed with about 1/8 inch rotated out of one side of the groove (make sure they are opposite each other, top and bottom). This ensures there will be no leaking at the joint.

Before installing the rear seal, add a few divots in the block with an awl or small punch. This gives the seal something to grab, so it won’t rotate.

Place a little dab of silicone in the seat and push the seal in place. Rotate the seal so that there is about 1/8 inch above the lip on one side and the same amount below on the other. This prevents the seal from leaking at the joint.

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/pistons-rods-cranks-oh-my-how-to-build-horsepower-with-a-buick-engine/

Connecting Rods

Nailheads

All of the Nailhead engines had forged rods. The 1953–1956 rods were 6 inches long and featured a wider bearing than the 1957–1966. There are two different rods: 1953 to mid-1955 264 ci and 322 ci; a pinch bolt held the wrist pin. On the mid-1955 to 1956 models, a more contemporary press-fit unit held the wrist pin, which was suitable for performance rebuilds. The 364 rods are 6-1/8 inches, and the 401 and 425 rods are 6-1/4 inches. The Buick rods are long for the stroke, so they have excellent rod/stroke ratios. This is even more evident with the 264, 322, and 364 engines. There are two different 364 rods, one used in 1957–1958 and one for the 1959–1961. The latter rod uses the 1959–1966 401 rod bolts and ARP bolts are available for these rods, but not the rods prior to 1959.

Forged Pontiac rods can be used in the 401 and 425 engines. These rods are longer and increase the rod/stroke ratio for better breathing. However, it takes a lot of work to make the 389 poncho rods for the Nailhead. These rods need to be lightened up and narrowed at the big end so the stock 401 bearing can be installed. The rod bolts hit the bottoms of the cylinders, so these must be clearanced on the block. The rod nuts contact the oil pan so a 1/4-inch spacer must be installed to drop the pan slightly. The Pontiac rod is 6-5/8-inch, and the 401-425 rod is 6-1/4-inch; therefore custom pistons with the wrist pin moved up are required.

Stock rods require very little work because they are forged and very strong. When rebuilding a Nailhead, a machine shop needs to magnaflux, shot-peen, and resize the rods and install ARP bolts. Always check the small ends of your rods, too. Buick had problems with wristpin knocking, and dealers installed oversize pins to fix it. If a standard pin is installed in these rods, it will slide out and ruin your cylinder wall.

Small-Block 350

The connecting rods for the 350 are quite durable and handle 500–550 hp, even though they are cast iron. When properly prepped, the stock rods are even suitable for all but the most extreme 350 builds. For prep guidelines, follow the steps in the next section for the big-block rods. While there are not many aftermarket Buick options, there are some. TA Performance offers reconditioned 350 rods that have been magnafluxed and shot-peened. In addition, the wrist pin end is checked for size, the crank end is resized, and ARP rod bolts are installed. TA Performance’s high-performance forged-aluminum connecting rod is an extreme-performance alternative. This rod is the strongest aftermarket Buick 350 rod available. Of course, it is the only aftermarket Buick 350 rod produced. This rod is ideal for racing or adding nitrous to your small-block Buick.

These 350 rods and pistons have been assembled and are ready for installation. Notice the discoloration on the little end (piston pin). This is from the heating process for press-fitting the piston pins to the rods. These rods have also been fitted with ARP rod bolts for security, and the pistons are Sealed Power Hypereutectic 10.5:1 units.

Machining other makes’ rods, such as Chrysler or Chevy, for the Buick 350 is another option. However, this is a very costly option and it yields a miniscule benefit. With the availability of the TA forged rod, the custom option just isn’t worth it.

Big Blocks

Buick installed forged-steel rods on the big blocks, which provides adequate strength for many highperformance applications. If the stock rods are properly prepared, they are even strong enough for racing, a nitrous oxide system, or revving up to 6,500 rpm. If you are going to spin the engine more than 6,500 rpm, the stock rods will not be strong enough. In addition, a set of aftermarket rods is required for a 125-hp, or more, shot of nitrous.

For the 455, these billet-aluminum rods are recommended for engines revving over 7,000 rpm or putting out more than 800 hp. They use 4304 chrome-moly rod bolts, which offer ultimate strength for 350 and big-block engines.

The TA Performance billet-steel rods are the very best connecting rods. These rods are the strongest available for Buicks and will clear the block with stroker cranks.

Numerous aftermarket connecting rod offerings provide a significant increase in strength over the stock rods. Some even provide a better rod/stroke ratio, but these rods require custom pistons. Chevrolet big block, Chrysler, and Pontiac rods require modification but can be adapted for use in a Buick, which opens up an entire selection of aftermarket options. Use of any non-Buick rod will require a custom piston. A big-block Chevy rod requires rod journal machining to accommodate the smaller Chevy bearing. Anytime you choose to run a non-Buick rod, the corresponding bearings and pins reference the rod type, not the Buick engine.

When fitting a Nailhead or big block with ARP rod bolts, you must check for clearance around the cap inset. The larger head can ride the inner edge, giving a false torque reading. Refacing the cap with a 21/32-inch counter bore eliminates the problem.

While there are lots of non-Buick rod options, there are quite a few aftermarket offerings, as well. TA Performance offers both forged-steel and billet-steel connecting rods. The 4340 billet-steel rods offer the most strength and lightest weight comparable to billet rods.
The length of the connecting rod is good for a little cheap HP. Some builders, such as Jack Merkel of Merkel Performance Engines, suggest that a 6.800-inch rod in the 455 engine will deliver a little extra power, but there is no more power to be found by using a longer rod. TA Performance, however, sells 455 rods up to 7.350 inches.

Properly preparing rods takes a little patience and time. When it’s done correctly, it yields a quality piece that will serve any vehicle well. When disassembling the motor, correctly label the rods for convenient assembly. The rods have matching caps that must be used with the same rod; otherwise, the bolts will not line up in the rods. Simply stamp each cap and rod on one side by using a mallet and set of number stamps. This ensures the rods are also installed in the right order and in the right direction. There is a small dimple on each rod, and each pair of rods must have the dimples facing each other for correct installation. Ask your machine shop to perform this process if it disassembles the engine. In addition, the shop should Magnaflux the rods and make sure they are not bent or cracked. Once the rods’ straightness and integrity have been verified, it’s time to get out the sander.

Use a belt sander with a small-diameter roller; or, a small-diameter sanding drum with medium-to-fine grit is ideal for removing the forging seam along the length of the rod. This reduces the stress risers, which accumulate heat and lead to cracking. Run the sander along the length of the rod, as you want the cuts to run the lengthwise instead of across the beam. An air-powered mini-belt sander works perfectly for this task. Once the rods are polished, a set of ARP rod bolts should be installed. At this stage, the rods are ready to be resized. A properly prepared set of rods should be good to 6,500 rpm without any issues.

V-6 Turbo

The 3.8-liter connecting rods used in all Buick V-6 turbo engines utilize a strong cap-screw design. This is the same design of connecting rod used in racing, including NASCAR. Introduced in 1975, this design proved to be twice as strong as the previous style. For most high-performance builds, the stock connecting rods provide more than enough strength for a turbo engine. In fact, rods are very seldom the cause of a turbo engine breakdown. The stock rods can take a tremendous amount of abuse.

These ARP rod bolts for the V-6 turbo are the best you can buy. The stock units are acceptable for street motors, but when an engine is apart, install new rod bolts. The new bolts will not have any prestretch, so the initial torque setting will be accurate.

There are several aftermarket rods available for those who are building extreme-performance and race-only turbo engines. K1 Technologies, a division of Carrillo, produces an H-beam 4340 forged-steel connecting rod fitted with ARP2000 rod bolts. These rods are suitable for just about any performance level turbo engine.
One note on the factory turbo rods: the bolt hole in the cap is not chamfered from the factory. This needs to be corrected when using aftermarket rod bolts, such as ARP. If not, the bolt head will not sit flush on the cap, and the bolt cannot be torqued correctly.

Rod Bolts

Always use ARP or similar high-performance rod bolts. They offer superior holding power and accurately measure bolt stretch. Reusing the stock bolts is never a good idea because these used stock bolts have been stretched, and they cannot be accurately measured and torqued. Save yourself a headache and pay the nominal amount for a set of good-quality rod bolts.

ARP has quite a selection of bolts for Buick engines. Whenever possible, use top-quality ARP bolts. This crank balancer bolt features a 1/2-inch square-drive head, which allows the builder to rotate the engine using just a breaker bar.

The rod bolts need to be torqued to the proper specs, or there will be problems with your engine. Too much torque can cause excessive friction in the engine, leading to bearing failure. Not enough torque and the oil pressure will lead to failure, as well. While the factory specs call for 35 to 45 ft-lbs for the connecting rods, most builders recommend 50 ft-lbs for high-performance applications. Once the rods are torqued down, the side clearance for the rods is an important clearance to be checked. There should be between 0.007- and 0.016-inch total clearance on the rod journals for performance rebuilds.

A forged piston yields the best strength, but at a slightly heavier weight. For low-revving engines, this is certainly a reasonable tradeoff for the improved performance. This Nailhead piston is a lightweight forged unit, which saves a lot more weight than traditional forging. The pent shape of the Nailhead combustion chamber requires a large pop-up in the center of the piston.

Pistons

Nailheads

The original Nailhead pistons on the 264 are 3-5/8-inch diameter and 4-5/16 inches on the 425. The 1953 has a very large dome — almost like a Hemi — while all others have the same basic dome shape. It is common for people to confuse a 10:1 Nailhead piston for a 12:1 piston because the dome profile makes it look like a higher compression unit. The large pent-roof chamber of the Nailhead cylinder head requires large piston domes, unlike the later Buick engines and most other makes. Buick used the size of the dome to change compression ratio of the piston. All factory pistons were cast, except a limited number of the 11:1 forged pistons for 401s offered in 1966. Cast pistons are perfectly acceptable for a Nailhead build. They are quiet when cold, and lighter than most forged pistons.

These Sealed Power forged pistons are exactly as stock but are forged instead of cast. They easily handle stock compression and deliver the strength of a forged piston.

Some racers have claimed they lost horsepower by switching from cast to forged pistons. Max Balchowsky, who built the cars in the movie Bullitt and a Buick Nailhead authority, said he ran cast pistons in Nailhead engines up to 7,000 rpm. The 1954–1955 Buick 264 and 322 pistons did not provide sufficient durability. These pistons often cracked and should be replaced with aftermarket cast or forged. There are a couple of ways to finish off cast and forged pistons, including CNC machining and cam grinding. “I have had some problem with CNC’d pistons,” said Russell Martin, a Nailhead engine expert. “They don’t seem to have a nice wear pattern when I have inspected used ones, so I prefer old-school cam-ground pistons.” Computer numerical control (CNC) machining uses a computer aided design (CAD) program to operate the machine. Cam-ground pistons feature an elliptical-shaped cross-section. This elliptical shape allows the piston to fit in the cylinder regardless of being hot or cold and allows for more expansion.

A stock-style low-compression V-6 piston is perfect for applications in which massive amounts of boost will be added.

Small-Block 350

The stock pistons, while decent, are not really suitable for high-performance use. The stock castings have a large, dished-out center with a little nipple sticking up. An easy way to identify the compression ratio of the piston is to look at the height of the nipple. A deep dish with a tall nipple is a low-compression engine. The stock compression ratios for the 1968–1980 350 are: 10.25:1 (1968–1969), 10.5:1 (1970), 8.5:1 (1971–1975), and 8.0:1 (1975–1980).

The 10.2:1 compression pistons are the only stock cast pistons currently available for the Buick 350. There are two types of aftermarket pistons: hypereutectic cast, and forged. To make an informed decision on piston selection, here is a brief description of each type.

The term “hypereutectic” means over eutectic, and eutectic is a metallurgical term that refers to the percentages of one element to another in a specific alloy for maintaining a common bond. Once the alloy reaches a certain percentage, any material that’s added remains a separate entity.

Typically, in aluminum alloys, the silicon content is eutectic at 12 percent. In the 1970s, it was discovered that adding more silicon to a cast piston produced less expansion when heated. This was very important for emissions, and it created a process of forcing additional silicon into the alloy, which remains in its granular form up to the 16 to 19-percent range. At 25 percent silicon, the pistons become hard and brittle and are subject to cracking.

Hypereutectic pistons can be machined for a tighter fit, and can run much closer tolerances in the cylinders because these pistons do not expand very much when heated. The rings form a tight seal on the cylinder wall, and this translates into less oil blow-by at start up. However, these pistons are not as strong as forged pistons and should not be used in any engine that uses more than a 125-hp shot of nitrous.

Forged pistons are formed from a heated slug of aluminum alloy. The alloy is forced into several increasingly detailed dies until it comes out as a very close representation of a finished piston. The forging is machined to precise specs and ready for installation. Forged pistons are very strong, and they can take a lot of abuse without breaking apart. Most importantly, these pistons are the only choice for any serious high-performance engine, but there are drawbacks.
Forged pistons are more expensive and fit more loosely in a cold cylinder than hypereutectic pistons because the forged pistons require loose tolerances to accommodate for a large expansion range. The expense of a forged piston depends on the engine. For a small-block Chevy, these pistons cost a little more than a cast piston. For a small-block Buick, however, they cost a bit more. As a matter of fact, TRW recently ceased production of the only production forged piston for the Buick 350. The other drawback is loose cylinder tolerances, which only affects the engines when they are cold. For basic mid-level daily driver engines, the strength of forged pistons would not justify the expense. For serious high-performance and race engines, forged pistons are a must.

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/pistons-rods-cranks-oh-my-how-to-build-horsepower-with-a-buick-engine/

Currently, a forged piston is not available; custom pistons are the only option besides stock cast or hypereutectic. Several manufacturers produce on-demand, custom pistons for Buick 350 engines. Diamond Racing is one of those companies. TA Performance and Poston Enterprises also offer forged Buick 350 pistons in a variety of compression ratios. Hypereutectic pistons for the Buick 350 typically have a 10.5:1 compression ratio. The price difference in a custom forged Buick 350 piston and a hypereutectic piston is typically $300 – $400. The Sealed Power hyper-eutectic piston is probably the most commonly used Buick 350 piston, and we used this piston on our 400-hp 350 build-up.

Big Blocks

The big blocks, predominately the 455, have quite a few brands of pistons available. As stated earlier, stock cast replacement pistons are not suitable for any application other than stock rebuilds. For high-HP engines, forged pistons are the best choice. In fact, forged pistons are required for any big-block engine that will turn more than 5,500 rpm or use more than a 125-hp shot of nitrous. The premium material for forged pistons is 2618 aluminum alloy because it’s both strong and light. In most cases, a thinner 1/16-inch file fit ring is used. For most street or light stripduty engines, the TRW forged pistons fit the bill. Beyond running a custom piston, there are several specialized forged pistons available for the 455. TA Performance offers a 2618 alloy lightweight race piston in 12.0:1 and custom compression ratios. This is the piston of choice for building a stroker engine. These stroker pistons also have the top ring placed higher on the piston, reducing the compression distance. In addition, this accommodates a longer rod for better rod ratios. TA also carries forged stock replacement pistons available in 8.5 and 10.1:1 compressions.

This 11:1 flat-top 455 piston from JE Pistons is a complete custom unit, which features 7-cc valve reliefs and is capable of producing 13:1 compression.

The camshaft used in any particular build may require notched pistons, so it is wise to speak with your cam supplier before ordering pistons. If your block has been decked or the heads have been milled, valve notches may be necessary. It is very important to dry-assemble your engine before final assembly to check valve clearance. A minimum piston-to-valve clearance of 0.100 inch should be maintained. A piston hitting a valve would not be a good way to break-in an engine.
Piston-to-wall clearance is also an important issue to consider. Inadequate piston-to-wall clearance can cause an engine to run hot. This is why most builders recommend honing every engine with torque plates. If you hone a block without a torque plate, you may have tight spots in your piston travel because the cylinders can potentially tweak when the head is torqued in place. Still, quite a few Buick builders dispute the value of torque plates for Buicks and will not use them. The choice is yours. For cast pistons (including hypereutectics), a clearance of 0.0015–0.002 inch is sufficient. The TRW forged pistons should run 0.003 to 0.004 inch of piston-to-wall clearance. Always follow the manufacturer’s instructions when using custom pistons. For most 2618 alloy pistons, at least 0.005- to 0.006-inch piston-to-wall clearance is required.

According to Mike Tomaszewski, owner and founder of TA Performance, “We do not sell, nor do we recommend, hypereutectic pistons. We have noticed an increase in failures due to the use of these types of pistons.” There are a few manufacturers that offer a hypereutectic piston for the 455, but these pistons are certainly stronger than the OEM cast piston and feature valve notches for use with larger camshafts. In addition, they are available in higher compression ratios than the stock cast pistons with their smaller dish and 0.010-inch less deck clearance. These hypereutectic pistons cost considerably less than forged pistons. TA Performance does not recommend these pistons because several customers have experienced piston breakage. In their opinion, hypereutectic pistons are too hard and brittle, allowing detonation to break a hypereutectic piston. This is an area of great debate. TA Performance is not alone in this argument, and they are certainly not opposed either. Many builders use hypereutectic pistons for high-performance street build-ups. It is this author’s opinion that there is a place for both.
The stock cast piston is not suitable for anything other than a stock rebuild. If you are building a mid-performance engine that’s below 600 hp for big blocks and less than 450 hp for the 350, the hypereutectic pistons will be more than adequate and should prove to be excellent in a properly built engine. With that said, do not use large amounts of nitrous on a hypereutectic piston. These pistons cannot take the shock and will break. A stock engine with stock cast pistons can typically take a 125-hp shot of nitrous. Use any more and you will start breaking pistons. If you plan on using nitrous, it would be a wise choice to use forged pistons. The same goes for any engine that is going to be revved over 6,000 rpm. If you are going to rev your engine this high, it is probably not a daily driver. If it will be raced, forged pistons are a must.

Turbo-V6
The pistons for the 3.8-liter V-6 turbo engines require special consideration. The forced-air induction engines place incredible demands on these pistons and make selection critical. The compression ratio for a turbo engine should not exceed 8:1 because a higher compression ratio can cause detonation, which can lead to engine failure. While high-octane or race fuels can remedy detonation, most owners don’t want to deal with hassle and/or expense of finding and running race-type fuel in a street car. Forged pistons are the best option for performance turbo engines because cast and hypereutectic piston are generally not strong enough to handle high-boost pressures. In fact, cast and hypereutectic pistons, if subjected to high enough intake pressures, can break apart in the cylinder and wreck the engine. Non-turbo pistons are not engineered or manufactured to withstand heat and stress of a turbo engine, so never use these pistons. The ring lands on a turbo piston are strengthened to support the boost pressure. Jack Merkel of Jack Merkel Performance engines recommends using TRW forged pistons with a piston to cylinder wall clearance of 0.0045-inch. Otherwise, you should follow the recommendations of the particular piston manufacturer. Piston weight is also a factor. Heavy pistons create more rotating mass and lose a fair amount of HP. Lightweight turbo pistons, made of 2618 aluminum, are recommended and provide superior performance.

There are two styles of locks for floating piston pins. The traditional lock ring on the right will work, but for more security — especially for street-driven engines — a spiral lock works better. However, it is more difficult to install.

Piston Pins

There are two types of wrist pins: press-fit and free-floating. Press-fit means the pins are pressed into the piston and rod. This wrist pin style has slightly more friction, so the pin remains stationary and the piston rotates on the pin. Controlled heating of the wrist pin side of the rod allows the pin to slide through the rod. As the rod cools, the pin is grabbed by the rod and held tight, leaving no possibility of the pin sliding out, ruining the cylinder walls. This is the most common method for Buick pistons. Jim Burek of Performance Automotive Enterprises recommends this style for all but race-only engines.

Free-floating wrist pins require honing the small end of the connecting rod so the pin can slide though easily. The wrist pin is held in place with two locking rings on both sides of the pistons. Some builders say these clips are prone to breakage. If one breaks, the pin can slide out and destroy the cylinder wall. Free-floating pins reduce friction and may free up a little HP on high-revving race engines, and they are certainly easier to assemble and disassemble. It’s a big plus for a race engine that gets torn down frequently. For street applications, they just are not necessary.

The key is to file fit your rings or use gapless rings, such as these rings from Total Seal.

Once the rings are installed, the pistons can be installed into the block. Use a spring compressor to help hold the springs in place before tapping the piston in the block with a soft mallet. This can be done without a compressor, but the $30–$40 to buy the compressor is well worth the added ease. This also reduces the risk of breaking rings.

A set of ARP main bolts securely holds down the crank. The crank should spin easily in the bearings with pre-lube. If it does not, there are several likely culprits: the tolerances are too tight, machining is incorrect, or a set of caps has switched positions.

This fully installed 455 rotating assembly is ready for some heads.

Measuring crankshaft end play is an important step. End play of 0.006 inch is acceptable.

The flexplate rounds out the rotating assembly. Since the Buick engines are externally balanced, using the correct flexplate is important. This stock unit is safe for engines up to about 500 hp.

ARP main studs were installed on this 350. Using studs instead of bolts greatly improves strength. The bolts stretch evenly since the threads are fully threaded in the block, and they do not twist while being torqued.

This SFI-approved unit from TA Performance is good for everything above 500 hp. Replace your flexplate on every rebuild. There’s no reason to risk a failure over a $50 part.

For the V-6 turbo, the billet main caps are a good idea for anything more powerful than stock. The block requires align-honing with main caps in place before assembly.

Rings

There are quite a few choices when it comes to piston rings. For stock and street-performance engines, a chrome-moly ring set provides good sealing and oil control. For high-horsepower and high-revving engines, the Federal Mogul or Speed-Pro plasma moly rings with a 1/16-inch-wide top ring is the best choice. These rings have superior resistance to moly flaking. The plasma coating increases lubrication, and the high melting point of the moly ensures a higher resistance to scuffing. When in doubt, use the plasma moly rings. If you are running nitrous, the plasma moly rings are the best choice because of the high resistance to heat and detonation. Most engine builders recommend a file-fit ring set. This allows the builder to set the gaps rather than use a by-the-chart gap in a standard set. Any high-performance application requires file-fit rings. Gapless rings, such as those from Total Seal, are not recommended for street engines. These rings feature a zero-gap second ring that interlocks, virtually eliminating combustion gas escaping through the rings. Removing the end gap can improve sealing, cooling, and HP. Some claim as much as a 5 percent hp increase by using a gapless top compression ring. Using a gapless top ring can eliminate the second compression ring on drag-race only engines. Deleting the second ring reduces friction and adds HP. But this is not something you would want to run on street engines. It’s for drag-race-only engines that get torn down after every race.

There is a lot of debate on this subject. In fact, many top builders recommend running a larger gap in the second ring because it reduces the pressure buildup between the rings. When the pressure drops, the top ring loses its seal at high rpm, resulting in better compression, better piston cooling, and reduced oil consumption. Pressure build-up between the rings will eventually force oil out of the rings, reduce lubrication, score the cylinders, and inevitably ruin the engine. By opening the gap on the second ring, the top ring is allowed to float, increasing sealing and allowing the gases to escape. This eliminates the possibility of the top ring lifting off the ring land.

After the type of rings has been selected, the file-fit process begins. Each ring is inserted into the cylinder bore, and a piston is used to push the ring inside, keeping the ring square. A set of feeler gauges is used to measure the gaps. Then each ring is filed using a ring grinder (available from Powerhouse tools, Snap-On, Matco, K-D, etc.) to keep the edges clean and burr-free. You could use a hand file, but why waste all that energy and time when a $40 tool does a better job? The ideal gap for the top ring is 0.016 to 0.018 inch, and the second ring is commonly set at 0.012 to 0.014 inch. The oil rings typically do not need sizing.
When the rings are sized, they need to be installed on the pistons. Opinions vary, but many contend that keeping the gaps apart is important for good sealing. Jim Burek, of Performance Automotive Enterprises, recommends setting the oil-ring spacer with the gap over one of the wrist pins. One oil ring is placed about in the middle of the piston between the wrist pins on one side. The other oil ring is placed 180 degrees opposed on the other side of the piston. The compression rings are typically installed with one gap over each wrist pin. It’s important to keep the gap opposed for the initial installation. The rings will move once the engine is running, so starting off with them opposed is the best bet.

Max-Performance 1970 Buick Gran Sport 455

Mike Garrison, owner of mrbuick.com, a Buick-specialty restoration shop, drag races this 1970 Buick GS as often as he can. TA Performance and Ruge Automotive built the bored and stroked 455 that runs as fast 10.18 seconds at 135.30 mph in the quarter mile. His business offers parts, such as core support rebuild kits, flywheel covers, and transmission brackets.

Engine Package:
• 535-ci V-8, 830 hp at 6,300 rpm; 802 ft-lb at 4,600 rpm
• 4.30-inch bore x 4.50-inch stroke
• 13.96:1 compression
• Steel billet 7-inch connecting rods
• TA 1610 inverted dome pistons with 1/16th rings, pin size: 0.927 inch x 2.950 inch, double spiral locks, piston weight: 546 grams
• Intake valve 2.19, 0.372 stem; Exhaust valve 1.75, 0.372 stem; Dual springs TA1190; seat pressure 230 lbs, open 540 lbs
• Comp Cams roller cam, 0.636 lift, 1.6 rockers 107-degree centerline
• 296-degree duration
• Cam degreed to 105 degrees
• Push rod size is 9.50 inch x 0.312 inch
• TA Street Eliminator heads: 58 cc Intake side flows: 334.9 cfm at 0.600 inch Exhaust side flows: 243.8 cfm at 0.600 inch
• Block supported with a block girdle
• Block is filled 50 percent with block hard
• Lifter gallery has been filled to the top of the bores with epoxy

TA Performance and Ruge Automotive bored and stroked Mike Garrison’s 830-hp, 535-ci Buick behemoth. Garrison owns and operates mrbuick.com, which sells parts for Buick restoration.

Garrison’s 1970 Buick GS hangs the wheels at Thunder Valley Raceway in Noble, Okalahoma, and is certainly a force to be reckoned with. Garrison is running low 10s and only a few tenths away from 9-second quarter-mile times.

Measuring Piston-to-Value Clearance by Len Emanuelson

Building a high-performance engine with various speed parts is complex business. To help avoid problems, you need to follow the basic engine-building rules, measuring every part to ensure they meet specs and trial-assembling the engine to check clearances. Valve-to-piston clearance is one of the most critical clearances and should be physically checked. Many first-time engine builders try to calculate the amount of valve clearance by the piston at top dead center (TDC) and the total lift at the valve. It just doesn’t work that way. You won’t know if the valve notches in the pistons are in the right place and exactly how everything meshes unless you go through the process. The most accurate test is to put clay on the top of the pistons, install the cylinder heads and valvetrain, and rotate the engine through a complete cycle — two complete revolutions.

Clay-Mation

Most professional engine builders recommend 0.100 inch for manual transmissions and as close as 0.070 inch for automatic transmission vehicles. Use 0.100 inch to be safe — and even more if you can get it — unless you’re building a world-championship race engine and need every bit of compression you can get. One missed shift at 7,000 rpm and valve float could instantly turn an expensive engine into a pile of junk. First, rinse the piston top with lacquer thinner for a clean, oil-free surface that clay can stick to. Then cut a couple of strips of clay about 3/16-inch thick and place them where you think the valves could hit the piston.

Clay is placed on the piston in the area where it comes in contact with the valves. Give the valves a light coat of lubricant to ensure the clay does not stick.

Engine Rotation

Spray the valves with a light coat of oil to prevent them from sticking to the clay and put the cylinder head back on the engine with a head gasket; torque to spec. Next, install the valvetrain and adjust the valve lash. Here’s the tricky part. Swap the hydraulic lifters for a mechanical lifter, a piece of wood dowel, or an aluminum slug that matches the pushrod seat height in the lifter. Why? A hydraulic lifter in a non-running engine will deflect the plunger and not give you true valve lift. In addition, you can take an old hydraulic lifter apart and fill it with something solid so the pushrod seat remains up against the retaining clip. Once you figure out this little issue, the rest is easy. Finally, rotate the crankshaft through two complete rotations. Slowly turn over the crank and feel for any resistance. If the engine doesn’t want to rotate completely, don’t force it. Remove the cylinder head and see what’s hitting.

The cylinder head is placed back on the engine. The pushrods and rockers are installed for a particular cylinder and set to spec.

Squish Check

Once you’ve successfully run the crankshaft through two complete revolutions, remove the cylinder head and inspect the clay. Hopefully, the clay was placed in the right location and stayed put for the valve opening and closings. (By cleaning the piston, the clay has plenty of stick, and by spraying the valves with light oil they won’t stick to the clay.) If you used thick-enough clay, the valves should leave fairly large impressions that are easy to identify.

Slowly rotate the engine by hand. If any hard resistance is encountered, stop and determine the source of the resistance. Resistance means something is wrong, and you need to resolve the issue to avoid serious damage. If all goes well, remove the head, and you will discover the valves have left marks like these.

Measurements

To determine valve-to-piston clearance, measure the deepest part of the groove made by the valve in the clay. Also, you must measure the deepest groove at the highest portion of the piston dome. Our Buick pistons had a big dish in the center, so the clearance was more than adequate. However, out on the raised edge of the piston, we measured the clay thickness with the wire-rod depth gauge of our dial caliper and measured only 0.075-inch clearance — just enough to squeak by. This big Buick red-lines at 6,000 rpm, and the automatic transmission should provide the safety factor.

Perform this valve-to-piston inspection when you trial-assemble your engine — you’ll be doing yourself a favor. Inadequate clearance means disassembling the engine, having the pistons notched at a machine shop, and starting the assembly process all over — a real pain!

Use the backside of the caliper to measure the depth of the clay. Do not press the base of the caliper into the clay; this alters the measurement.

Written by Jefferson Bryant and republished with permission of CarTech Inc

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/pistons-rods-cranks-oh-my-how-to-build-horsepower-with-a-buick-engine/

The post Pistons, Rods, & Cranks, Oh My! How to Build Horsepower With a Buick Engine appeared first on Muscle Car DIY.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://musclecardiy.com/ pushrods-lifters-101-everything-you-need-to-know /

Pushrods are available in three-piece and one-piece designs. A three-piece design features a tube with hardened lower and upper tips. A one-piece design features a hard­ened one-piece centerless-ground machined pushrod. Wall thickness of the tube varies depending on appli­cation, with most common perfor­mance thickness of .080, .083, .135, and .165 inch. Street and many race applications call for .080- to .083-inch wall, with thicker wall pushrods required for more extreme applica­tions. Pushrod diameters vary, again depending on the application. Typ­ical diameters include 5/16 and 3/8 inch, with larger diameters such as 11/16, 7/16, with extra-beefy 1/2 and 9/16 inch often required for race engines that feature very high valvespring rates. Smaller diameter pushrods are also available for appli­cations requiring 3/16- and 1/4-inch diameters. Common tube materials, depending on application, include the use of 4130/4135 chrome-moly, as well as high-tensile tool steel. The larger the diameter and the thicker the wall, the less subject the push­rod is to deflection during high-RPM conditions. Bear in mind that larger diameters and thicker walls often translate into increased valvetrain weight. Space considerations deter­mine diameter, with regard to push­rod passages in the cylinder head. Bigger and heavier isn’t always better.

Although checking new push­rods for runout probably isn’t nec­essary, it doesn’t hurt just to make sure that none have been damaged during handling. Used pushrods should always be checked for runout. Pushrods can be checked easily for runout (bend) by placing the push­rod in a horizontal cradle (a dedi­cated pushrod checker stand is best). A dial indicator that is mounted to the stand is adjusted so that the indi­cator plunger contacts the pushrod at its center. The dial indicator is then adjusted so that the plunger is compressed against the pushrod to achieve a preload of about .050 inch. The indicator gauge is then adjusted to read zero on the gauge. The push­rod is then slowly rotated, noting the amount of runout. Generally speak­ing, a maximum allowable runout is about .001 to .0015 inch, with 0 to a maximum of .0005 inch preferred.

Never assume pushrod length based only on published specifications. Because of variations in a specific build such as block and head deck height rocker arm ratio, valve length, the size of your camshaft’s base circle, thickness of the cylinder head gasket, etc., it’s critical to take the time to determine the precise pushrod length(s) required. You should also take the time to measure for pushrod length at all intake and exhaust locations, or at least at the front and rear cylinders, in case your block decks are not perfectly parallel and equidistant from the crankshaft centerline.

Some engine designs, where offset rocker arms are employed, may require varying pushrod lengths. For a recent 632-ci race engine, using a Jesel rocker system on Dart Big Chief II cylinder heads, the exhaust pushrods were 1/2 inch in diameter with a length of 11.124 inches, while intake pushrods were 7/16-inch diameter with lengths of both 10.953 and 10.805 inches, depending on location.

Hardened tips are needed at each end of the pushrod to withstand the frictional loads at the lifter and rocker arm. Note the taper at each upper and lower tip on this racing pushrod, to provide added clearance at the lifter and rocker, where the pushrod diameter is larger than the lifter cup and rocker arm cup as shown on this 1/2-inch diameter pushrod.

Performance aftermarket pushrods are often laser-etched by the manufacturer for easy size reference. This pushrod is identified as having a wall thickness of .080 inch and a length of 9.000 inches.

If necessary, use a micrometer to measure pushrod outer diameter.

This pushrod has been laser-etched to indicate diameter, wall thickness, and length. Not all pushrod manufacturers provide this easy-reference identification.

Checking a pushrod for straightness can be achieved by slowly rolling the pushrod on a plate of clean glass.

A dedicated pushrod concentricity checker makes verifying pushrod straightness easy and precise. The pushrod is positioned on the stand’s cradles. The dial indicator plunger is positioned at the center of the pushrod. The gauge is zeroed, and the pushrod is slowly rotated to measure for any runout.

An alternative method for check­ing pushrod runout is to slowly roll a clean pushrod on a perfectly flat surface, such as a glass panel or a pre­cision steel or granite platform. The pushrod should roll smoothly with no daylight visible between the flat surface and the center of the push­rod (any gap between the center of the pushrod and the flat surface can be measured with a feeler gauge). If runout is excessive, the pushrod must be replaced. Don’t attempt to straighten it.

When building a stock engine to original specifications, a stock-length pushrod will likely suffice. However, given variables such as block deck height resurfacing, cylinder head deck resurfacing, valve length, a cam­shaft upgrade that features a different height base circle, use of a thicker or thinner cylinder head gasket, etc., it’s always wise to measure to deter­mine the correct pushrod length for a given application. Off-the-shelf push­rods are available in a wide range of lengths to suit any application, usu­ally in increments of .050 inch. In addition, custom-length pushrods can be ordered from a number of pushrod manufacturers easily, includ­ing Trend, Comp Cams, Lunati, Crane, and others. Whereas the use of hydraulic lifters and/or adjust­able rocker arms allow some leeway regarding length, pushrod length is especially critical when using solid lifters and/or nonadjustable rockers.

Always measure each pushrod location for length. Don’t assume that the measured length for number-1 cylinder intake location suffices for all other locations. If the block deck has not been squared and equalized on both decks, pushrods may need to be shorter at one end and longer at the opposite end of the block. Also, some engine designs that feature offset rocker arms may require specific pushrod lengths for intake and exhaust locations.

Measuring for Pushrod Length

A checking pushrod provides an easy method of determining correct length. This is a temporary pushrod that is adjustable for length.
With the engine long-block assembled (crankshaft, camshaft, timing set, lifters, cylinder head gas­kets, and heads), install a checking pushrod into the first location to be checked (for instance, number-1 intake location). Choose a checking pushrod that provides a length range that suits your engine. As an exam­ple, let’s say that your engine “nor­mally” requires a pushrod length of 7.500 inches. Choose a checking pushrod that provides a range of 7.000 to 8.000 inches.

Remove the number-1 intake valvespring and replace it with a light checking spring. This makes it easier to rotate the engine and doesn’t fight you as you check your measurement.

Rotate the crankshaft to place the camshaft lobe of the location to be checked on its base circle. In other words, the lifter must be on the base circle and not on the lobe ramp. This places the lifter as far down as it can be in its bore.

Wipe the valvestem tip clean to remove any oil. Using a marker pen, paint the valvestem tip. This pro­vides a witness mark as the rocker tip travels across the valvestem tip.

Measuring for pushrod length is made easier with the use of light checking valvesprings. Use of these light springs maintains rocker arm geometry while checking, but doesn’t cause unwanted resistance while trying to measure for required pushrod length.

Some checking pushrods, such as this example from Comp Cams, feature a row of alignment marks. When the adjustment is fully collapsed as shown here and the two sections butt against each other, the length is as indicated on the body (for example, 7.000 inches).

As the body is lengthened by rotating the sections, each full rotation indicates a change in length of .050 inch. In this example, a 7.000-inch minimum length checking pushrod has been rotated by one full revolution, with the index marks aligned. This now indicates a length of 7.050 inches. This “micrometer” design makes it easier to determine the adjusted length, especially if a long caliper is not available for measuring.

Some checking pushrod designs are multipiece, allowing adjustments in body length and tip-to-body lengths. If the checking pushrod does not feature etched increment marks, it’s best to place matchmarks on the body sections prior to removal from the engine. Then very carefully remove the checking pushrod to avoid accidental rotation, which alters length.

Adjustable pushrod checkers must be handled very carefully when removing from the engine following on-engine adjustment. Any rotation of the checking pushrod alters the measurement. It’s a good idea to perform the adjustment and on-bench measurement several times to verify that the correct length has been achieved.

Checking pushrods are available in a variety of lengths and adjustment ranges. If you build a variety of engine types, it’s best to keep a wide range of checking pushrods in your inventory to cover all potential builds.

With camshaft and lifter installed, a light valvespring and rocker arm is put into place and an adjustable checking pushrod is installed. The cam has been rotated so that the lifter is on the lobe’s base circle. The checking pushrod is carefully adjusted to accommodate the application. If solid lifters are being used, the checking pushrod is adjusted to achieve zero lash at the rocker-to-valve. If hydraulic lifters are used, a slight preload can be added to the measured length of the checking pushrod to suit the requirements of the specific lifters. This added length for lifter preload is in the range of .035 to .050 inch, depending on the recommendation of the lifter manufacturer.

A long caliper is ideal for measuring pushrod length. Obtain a caliper capable of handling a range up to about 12 inches to cover all potential applications.

If the pushrod style requires an upper cup design, place a ball bearing into the checking pushrod’s cup, but do this after the checking pushrod has been adjusted and removed from the engine. Otherwise, if you measure the checking pushrod by placing the caliper’s anvil into the cup, you will have an incorrect measurement. Before measuring the checking pushrod with the ball in place, first measure the ball diameter. The ball diameter is subtracted from the overall measurement to obtain the correct length. The ball simply provides an easy way to make the measurement in terms of caliper contact.

Certain valvetrain designs feature adjustable ball tips on the rocker arm pushrod ends and as a result require pushrods with upper cups. Although the rocker arm ball nestles into the cup during on-engine pushrod measurement, it is extremely difficult to measure the checking pushrod’s cup with a caliper.

With the upper cup clean, insert the ball.

With the ball in place, allow the caliper to contact both the ball and the lower tip.

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://musclecardiy.com/ pushrods-lifters-101-everything-you-need-to-know /

This pushrod, with a ball in the upper cup, measures an overall length of 7.6995 inches. Subtracting the ball diameter of .3125 inch, the ideal pushrod length is 7.3870 inches. Depending on the length offered by a pushrod maker, you could then order a length of 7.385 inches, with fine-tuning via valve-lash adjustment.

If the actual pushrod or pushrod checker features an oil hole, measuring with a caliper can be imprecise due to the caliper contacting the hole instead of the full radius. Using a gauged pushrod checker where you know that each full rotation of adjustment represents a distance of .050 inch avoids this variable. If the checking pushrod features no oil hole, caliper measuring can directly achieve the proper results.

When checking for pushrod length, mark the valvestem tip with a black marker before installing the rocker arm. With the checking pushrod in place, the crank is rotated, causing the rocker arm to move through its entire sweep. With the rocker arm removed, check the witness mark on the valvestem tip. Ideally the rub mark should be centered on the tip. If the rub mark is biased toward the center of the engine, the pushrod is too short. If the rub mark is biased toward the exhaust side of the cylinder head, the pushrod is too long.

During pushrod length checking, verify that the rocker arm tip is relatively centered fore/aft on the valvestem tip.

Adjust the length of the check­ing pushrod to the theoretical length (again, if your engine normally calls for a 7.500-inch length, adjust the pushrod to that length).
Install the checking pushrod, making sure that the lower tip cen­ters properly into the lifter.

Install the rocker arm. If the rocker is nonadjustable, tighten the rocker arm bolt or nut to final torque value. If the rocker arm is adjustable, install at approximately the center of its adjustment.

Pushrod length is affected by the type of lifters being used. I delve into that aspect in Chapter 9. Rotate the crankshaft a full two revolutions (360 degrees).
Remove the rocker arm and inspect the witness rub mark on the valvestem tip. Ideally, the rub mark should be at the center of the valvestem tip. If the rub mark is off-center and closer to the intake side of the head, the pushrod is too short. If the rub mark is biased toward the exhaust side of the head, the pushrod is too long.

When the checking pushrod has been adjusted for proper length, carefully remove the pushrod, being extremely careful to avoid changing its length (if the checking pushrod does not feature index marks, place a matchmark that aligns the two sections as a reference). Using a long caliper, carefully measure the push­rod. If you have hydraulic lifters, add to this length an appropriate amount to compensate for lifter preload, which may be in the range of .035 to .100 inch, depending on the specific style of lifter (check with the maker of the lifters for recommended preload).

If your pushrod design features a radius tip at each end, measure over­all length. If your pushrod design features a cup at the upper end (for rockers that feature an adjustable ball), your measurement needs to include the distance from the lower tip to the inside of the cup. Do not attempt to measure the cup’s seat in relation to the upper edge of the cup. Instead, use a 5/16-inch ball to insert into the cup. This provides a contact point for the caliper. After you mea­sure the checking pushrod with the ball in place, subtract the ball diam­eter to obtain the actual length. For instance, if the overall measurement from the lower tip to the outside of the ball is 7.8125 inches and the ball measures .3125 inch in diameter, the final pushrod length is 7.500 inches.

When measuring a checking pushrod, most feature a fully radiused tip at each end, with no oil holes. If your style of desired pushrod does feature an oil passage, the missing end of the radius (due to the oil hole diameter and amount of chamfer at the oil hole) can lead to an imprecise measurement when using a caliper to measure length.

The theoretical length assumes that the pushrod has no oil hole in the end of it. Therefore, the radius at either end is complete, which length­ens the pushrod approximately .017 inch in the case of a 5/16-inch push­rod with .100-inch-diameter oil holes, minimally chamfered.

The actual length is what you measure if you had a caliper large enough to measure over the oil holes at each end of the pushrod. Unfortu­nately, this measurement is affected not only by the diameter of the oil holes but also by the entrance cham­fer for each oil hole.

The gauge length is the most difficult to measure, as it requires a special-length checking gauge. This is because the oil holes and their chamfers are eliminated from the measurement. The only problem is that not all companies use the same gauge diameter. Leading makers such as Comp and Trend use a .140-inch gauge (which adds .017 inch at each end if measured with a caliper). If using a gauge-type pushrod checker that features no oil holes, the vari­able of the oil hole and its chamfer are eliminated, allowing you to use a caliper or to simply go by the number of full revolutions of the adjustable checker (with each full revolution equaling a distance of .050 inch).

Gauge-type adjustable pushrod checkers (such as those offered by Trend, Comp, and others) are marked with a standard length stamped in them. This is the length of the adjust­able pushrod when the two halves are screwed together completely. As mentioned previously, extending the adjustable pushrod one full rota­tion lengthens the overall length by .050 inch. For example, a pushrod stamped 7.800 inches and screwed apart one rotation has a length of 7.850 inches (7.800 + .050). There­fore, you order the part number from the catalog that matches this gauge length because they are listed by gauge length.

The length of the required push­rod also depends on the type of lifter being used. If solid lifters are to be used, the rocker arms feature a lash adjustment. Therefore, with the lifter on the cam base circle, adjust the checking pushrod to the point where you achieve zero lash. Adjustment at the rocker arm then allows you to set the required valve lash.

If hydraulic lifters are to be used, you need to consider the plunge travel inside the lifter. If you are using a light checking valvespring, you can carefully adjust the checking push­rod until it just makes contact with the lifter, without compressing the lifter. An alternative is to use a spare lifter of exactly the same make, style, and part number, and tack-weld the plunger, effectively turning it into a solid lifter. This eliminates the chance of accidentally compressing the lifter during adjustment of the checking pushrod. After the check­ing pushrod has been adjusted to zero lash and measured for length, add the required amount to antici­pate lifter preload (again, this com­pensation may be .03 to .050 inch or so, depending on the lifter spec­ifications). Bear in mind that some hydraulic lifters are designed with very short travel distance (a sort of hybrid between a solid and hydraulic design). Check with the lifter maker for recommended lifter preload to consider when determining pushrod length.

After you’ve determined the cor­rect pushrod length for your engine and have purchased the new push­rods, always check to verify proper length. Test fit the pushrods, follow­ing the same procedure outlined here for determining length, as installed to the engine. Make sure that travel is correct, where you achieve a fully open valve condition without coil bind and a fully closed condition when the lifter is on the cam’s base circle.

Using a marker, paint the valve-stem tips, install the rockers, and rotate the crank two full revolutions, then remove the rockers and exam­ine the witness rub marks. Again, if the rub mark is too far toward the intake side, the pushrod is too short. If the rub mark is too far toward the exhaust side, the pushrod is too long. If the rub mark is centered, the push­rod length is okay.

If you find that you have an incorrect length with the new push­rods, it means that you’ve likely made a mistake during your initial length check. Unless the new push­rods were custom ordered with a unique length, you should be able to return and reorder. Never blindly assume that the new pushrods are correct. Always double-check.

Written by Mike Mavrigian and republished with permission of CarTech Inc

This tech tip is from the full book, AUTOMOTIVE MACHINING: A GUIDE TO BORING, DECKING, HONING & MORE .

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://musclecardiy.com/ pushrods-lifters-101-everything-you-need-to-know /

The post Pushrods & Lifters 101: Everything You Need To Know appeared first on Muscle Car DIY.

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/ how-to-upgrade-the-oiling-system-in-buick-engines/

On every Buick engine except the Nailhead, the oil pump is located in the timing cover and powered by the distributor. It’s driven from an integral drive gear on the camshaft. The pump draws oil from a 1/2-inch oil pick-up tube (5/8-inch on 1971 and later 455s) on the passenger side of the oil pan. The pump gears are pressurized and the oil is forced through the oil filter. Then, oil is sent to the crankshaft through holes in the main bearing journals. Next, oil is pumped to the connecting rods through passages in the crankshaft. At the same time, oil is pumped up to the passenger-side lifter galley, across the front cam bearing to the driver’s side lifter galley. For 455, 1970 and later 350, and 400 Stage 1 engines, pressurized oil from the lifters is pushed up through hollow pushrods and enters the rocker at the pushrod tip and oils the rockers. The 1968–1969 non-Stage 1 400, 430, and 350 engines use specific rocker arm shafts to oil the rockers and pushrod tips. These engines use solid pushrods. While these pushrods are still available, the conversion to the later (and more efficient) hollow-pushrod design is simple and will be discussed in the next chapter.

Disassembly and Modification

The block should be fully disassembled and cleaned before any modifications are made. Each engine build is different, so how deep you go into the engine determines how much you will modify. If you are boring the engine, oil system modifications should be done before the machine work, so you have a perfectly clean and prepped block that’s ready to be built. These mods are not an absolute must, but since the engine is apart, it’s a good idea to do them. Each of these modifications can be performed on all of the later Buick blocks. However, some of the hole sizes may be different.

Cleaning up the 3.8-liter V-6 turbo bores is a quick way to increase the speed at which the oil returns to the pan. A basic clean-up gets the job done.

Cleaning up the 3.8-liter V-6 turbo bores is a quick way to increase the speed at which the oil returns to the pan. A basic clean-up gets the job done.

Cleaning up the flashing on the casting should be done on every engine build. It is quick, easy, and results in faster oil flow from the rockers back to the pan. Mount the engine on a rotating stand. A die-grinder with a fine carbide cone bit is the best tool to use for this job. Smoothing out the flashing in the lifter galley is most important. The idea is to eliminate the rough edges that will catch the oil and inhibit its downward flow. Perform a basic cleanup and don’t go crazy. The Buick engines don’t have a lot of material around the lifter bores, so you don’t want to remove too much material and create a problem. Use the same process for cleaning up the casting flash around the main webs. This job isn’t mandatory, but it will certainly reduce the chances of them becoming a stress riser and cracking. If you are building a severe-duty engine, this is a really good idea.
In addition to cleaning up the flashing around the lifter bores, adding a lifter bore girdle is required when a roller cam is used. There are bolt-in lifter girdles and custom-built epoxied-in units. These are only necessary when using a roller cam, and will be discussed further in Chapter 9: Race Engines.

The weak lifter bores need to be reinforced for a high-lift cam profile or roller lifters. The bores will break out under the outward stress from the lifters. This TA Performance bolt-in lifter girdle is a simple way to eliminate the problem.

Now that everything is trimmed up, the real work can begin. On the main bearing journals, the number 2, -3, and -4 oil-feed holes should be opened up. Do this by drilling the original 1/4-inch hole with a 5/16-inch drill bit. It is extremely important to start the drilling straight on the hole, or you run the risk of running off the edge of the corresponding cam bearing. These holes must be drilled all the way past the cam bearing, to a depth of 3-3/4 inches; a standard-length drill bit should be able to accomplish this task; just make sure it is sharp. The stock main bearings (on a 350) have a 3/16-inch hole in them. If you are leaving the stock oil holes alone, the main bearing holes should be opened up to 1/4 inch; if you are making the previously mentioned modification, the bearing holes should be opened up to the corresponding 5-1/16-inch size.

The number-2, -3, and -4 main bearing saddle oiling holes on this 350 were opened up from 1/4 inch to 5/16 inch, while being careful not to hit the cam bearing. These holes must go to a depth of 3-3/4 inches.

Main bearing oil hole alignment is one of the biggest problems with Buick engines. To check this, you will need either the original bearings, or even better, the bearings used in the rebuild. On our 350, we found the number-2, -3, -4, and -5 main journals had to be corrected. This is a very important step — if you skip it, you could end up covering more than half of the hole, which could result in a catastrophic failure. Once the problems have been identified, the fix is pretty simple. With the bearing in place, mark the journal inside the hole where the misalignment occurs. Using the die-grinder with the cone carbide, chamfer the oiling holes where the journal was marked. This allows the oil to easily enter the bearings and not get hung up on the edges. It is all right if the hole ends up slightly larger than the bearing hole, just as long as they line up afterwards. This step should be done on every single Buick engine build: stock, high performance, or race.

The bearing oil feed holes must be enlarged. Otherwise, the block mod does no good.

Checking the bearings for alignment is important. This must be correct in order to get adequate oiling.

The next step is to open up the main oil suction feed on the front of the block. This step is paramount to increasing the oil flow to the rest of the engine. Use a 12-inch long 1/2-inch drill bit, and drill the suction side oil galley from the front of the block to the oil pick-up tube. Patiently drill and add cutting oil as you go. Don’t try to do this all at once. Drill about an inch, pull the bit out, remove the chaff from the drill bit, and proceed another inch or so. Be sure to keep the bit level and do not go off at an angle. This passage is 10-1/2 inches deep, so take your time and be patient. You can do all the drilling with a cordless drill, but it’s much better to use a corded drill because the lighter weight will reduce the strain on your arms and allow you to drill level. Another plus of a corded drill is more torque and no recharge time.

Using a carbide tip, chamfer the edge of the hole in the bearing saddle. This had to be done to the number-2, -3, -4, and -5 saddles.

Rechecking the bearing shows a proper fit.

On the 350, the oil suction passage from the block to oil pump hole needs to be enlarged to 1/2 inch. The passage is 10-1/2 inches deep.

On the 350, the oil suction passage from the block to oil pump hole needs to be enlarged to 1/2 inch. The passage is 10-1/2 inches deep.

The main oil-feed passage needs to be opened from the oil-pressure sending unit to just short of the main cam bearing. The depth is 4 inches, and it’s drilled out to 7/16 inch. The passage can be opened up to 1/2 inch, but it requires tapping the oil sensor to a 3/8-inch pipe thread.

Again, drill slowly and keep the drill depth to 4 inches. Using cutting oil makes the work a little easier and keeps the chaff from binding up the bit. Pull the bit out of the hole after drilling each inch, and clean off the chaff.

The 350 requires the following procedure: Drill the oil pick-up tube passage to 1/2 inch. This will intersect with the previous passage from the front of the block. The depth on this passage is 3 inches. Again, take your time and use cutting oil — it will help.

The previous step can also (and should) be performed on the early big blocks (1968–1970 400, 430, and 455 engines). In 1971, Buick realized the 1/2-inch suction feed line was not adequate and bumped the oil pick-up tube size to 5/8 inch. Opening the 1/2-inch passage in the 400 and 430 blocks to 9/16 inch is sufficient; the 455 blocks can be drilled to 5/8 inch. Whether you choose to drill the passage or leave it as is, the 5/8-inch pick-up tube should used in all big-block builds.
Buick engines tend to lose oil pressure to the lifters over time. The problem is the way Buick engines feed the lifters. The oil must travel across the front cam journal before it feeds to the driver-side lifters. After the engine has some miles on it (typically after 10,000 miles), the cam bearing begins to fill the oiling hole with bearing material, cutting off the oil supply to the driver-side lifters. Part of the fix for this is to open the main feed line from the pump to passenger side lifter galley. By using a 12-inch-long 7/16-inch drill bit, the passage will be opened up enough to add significant flow to the lifter galley and more pressure to the cam bearing. This passage runs from the oil-pressure sending unit to just shy of the front cam bearing, a depth of 4 inches. Using the 7/16-inch bit, the threads for the sending unit will remain untouched (if you are careful). You can open this to 1/2 inch, but that will require retapping the oil-pressure sending-unit hole to 3/8-inch pipe thread from the factory 1/4-inch thread.

For the 3.8-liter turbo engines, there are a couple of extra steps that should be taken, because the oil pump not only feeds the engine but the turbo, as well. In high-performance street and street/strip engines, deburring and smoothing out the oil-pump walls provides a serious increase in oil flow. Extreme-performance engines, such as full-race applications, should have an external oil line running from the turbo oil supply fitting to the passenger-side lifter oil galley in the rear of the block. This external line will increase volume and pressure to the rear mains and rod bearings because oil is being supplied from both the front and the rear ends of the oil galley, rather than just from the front. To accomplish this, the turbo-feed fitting at the block (front, passenger side) is drilled to 9/16 inch to just before the cam bearing as in the 350 and big-block engines. Then, using a 19/32-inch standard drill bit, the passage is drilled 1 inch deep. The threads must be retapped to 3/8-inch pipe thread to accommodate the new fitting and 3/8-inch external line.

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/ how-to-upgrade-the-oiling-system-in-buick-engines/

Crankshaft Mods

There are two camps when it comes to increasing the oiling capability of the crankshaft. One side advocates cross-drilling the crank, while the other group argues that cross-drilling weakens the crank, and therefore the best bet is to use fully grooved main bearings. Here are the advantages and drawbacks for both:
Cross-drilling the crankshaft supplies more oil to the crank, and therefore the rods. By adding a second oil feed hole, oil is supplied to the crank during its entire rotation. Otherwise, with a half-groove main bearing, oil is supplied to the rod bearings only when the oil feed passage aligns with the oil groove, which is about half the rotation of the crankshaft. This leaves the rods waiting for fresh oil for the second half of the crank rotation. Under high RPM, extreme heat is generated on the surface of the rod journal and rod bearing, requiring an abundant supply of oil to maintain reasonable temperatures. This is reason for continuous oil feed. Therefore, cross-drilling provides this constant supply of oil as one feed hole rotates past the oil feed groove, and the other feed hole enters into the groove.

The cheaper alternative is running a set of 3/4-inch groove bearings. This option slightly reduces the bearing surface but not enough to be an issue with a properly modified oiling system.

In the early 1970s Buick released a service bulletin instructing dealers to cross-drill the crankshaft for heavy-duty applications. This solution worked well for Buick and quite a few manufacturers. There are, however, a few drawbacks. With increasing RPM, centrifugal force pushed oil away from the center of the crankshaft. The oil pump must then overcome this force with higher pressure to continue to feed adequate oil volume to the rod bearings. The original oil feed hole is drilled at an angle, so the oil passes through the center of the main journal. The centrifugal force acting on that passage is not as high as the cross-drilled passage, so the oil pressure does not have to be as high. Cross-drilling a crank can actually force oil out of the hole and reduce oil flow to the rods. Some builders feel cross-drilling a nodular iron crankshaft will weaken the crank and lead to failure.

Engine builders on the other side of the fence recommend using fully grooved main bearings. These bearings feature 360-degree grooves, which accomplish the same thing as cross-drilling without the drawbacks of weakening the crankshaft and centrifugal force pushing the oil out. However, the proponents of cross-drilling believe that grooved bearings reduce the bearing surface too much, resulting in a shorter life. Since the big Buick crankshafts have such large main journals, this is a good point. If you are building a mild-performance engine and it won’t rev beyond 5,500 rpm, then the stock bearings and crank will be sufficient. If you are building anything more potent, then either method will increase oiling over stock. The simplest and most inexpensive method is to use fully-grooved bearings. As a side note, the 401- and 425-ci Nailhead engines came with grooved crankshafts, which do the same thing as grooved bearings.

TA Performance is one of several Buick specialists that offer fully grooved main bearings for the small-and big-block Buicks. Yet there are some other options. Federal-Mogul offers 3/4-grooved main bearings, leaving a little more bearing surface and saving the builder from cross-drilling the crank. The other option is to buy a standard set of main bearings and have them grooved at the machine shop. The number-5 main journal bearing should not be grooved, as this could lead to a leak at the back of the block.

Use high-quality bearings in the 3.8-liter turbo engines because a 6-cylinder engine puts more load on its main bearings. Federal-Mogul manufactures an aluminum alloy main bearing set for the turbo engine. These bearings offer a more accurate finish because they are bored to size, not stamped like other brands. The Federal-Mogul units have a smaller oiling hole than the feed holes in the block, so the bearings need to be drilled out to 5/16 inch in all 3.8-liter builds to increase oil volume. Once the bearings are drilled, they should be cleaned and deburred with a deburring tool and hit with an ultra-fine Scotch-Brite pad and motor oil. These bearings are of the 3/4-groove variety, which can be machined to fully grooved by your machine shop if you choose to have it done.

While on the subject of crankshafts, there is another inexpensive modification that adds extra insurance. Chamfering the oiling holes in the crankshaft allows the oil to flow inside the crank with less restriction and increase the area for the oil to move into the crank. Also, it is always a good idea to have the crank degreed and indexed. Most of the time, the stock crank is not accurately indexed, and the machine shop will perform this job to ensure the rod journals are 90 degrees apart. Indexing the crank takes the stroke and swing degrees and grinds the crank to match. This ensures proper crank timing, which is important for proper camshaft timing.

Close Bearing Tolerances

One of the most important steps in building any Buick engine is measuring bearing tolerances. Be careful when taking your Buick engine to a builder that specializes in Chevy engines. Chevy engines are built to run loose, running bearing tolerances .0035-inch and more. This is perfectly acceptable for a Chevy. If you run a Buick engine that loose, it will likely blow up before you can even shut the hood. Most Buick builders recommend a tolerance of .0020 inch for the number-1, -2, -3, and -4 main bearings for high-performance street or street/strip applications. For serious drag cars, a tolerance of 0.0025 inch is sufficient. For the number-5 rear main bearing, a 0.002 inch to 0.0025 inch tolerance is recommended for all engines. For the connecting rods, the same 0.002 inch to 0.0025 inch tolerances are recommended. The reason for the tight tolerances is due to fact that the Buick’s large 3.25-inch main bearing journal diameter requires more pressure to supply oil to the rod bearings. If you run the bearings loose, the oil will be allowed to squeeze out of the bearings, limiting supply to the rods. The stock specs on a 455 are 0.007 0.0011 inch, which is a little too tight for a high-performance Buick.

Checking the crank for clearances can be done with a micrometer or plastigauge. Most top-end builders only use precision tools, such as micrometers and calipers, but these tools can be expensive.

It is highly recommended that all 350 and big-block Buick cranks be turned down 0.010 inch. The reasoning being: most of these engines will not have maintained the factory tolerances and will have flat spots and be seriously out of specification. You can build a Buick without turning the crank this much, but to achieve the tight tolerances, it is a good idea to start with a smooth, concentric journal that will yield the best fit in the block. When checking your tolerances, there are two methods: Plastigauge and micrometers. Using micrometers is the most accurate, and therefore it is the method of choice. They are however, fairly expensive and can be confusing for the novice builder to use. Plastigauge is fairly simple to use and typically yields fairly accurate results. If you are building a mild street engine, plastigauge will probably get the job done, but for serious performance engines, a micrometer is the best way to ensure proper measurements. If you do not have access to a set of micrometers, most machine shops will measure the tolerances for a nominal charge. You should have this done when the machine work is performed to save some time and money.

We checked the main bearing clearances with a micrometer and dial bore gauge, and verified the measurements with plastigauge. Both readings were accurate. If you have the means, use the precision tools because they will always yield accurate results.

As for the 3.8-liter V-6 turbo, only turn the crank the minimum amount, and do not exceed 0.010 inch for any performance application. Be sure to tell your machine shop to cut the crank on the high side (tighter, less cut). The turbo engines need even tighter tolerances than the V-8s. A main bearing clearance should be 0.0015 to 0.002 inch (closer to the 0.0015-inch side is better), while the rod bearing clearance should run 0.0018 to 0.0025 inch. When using the 3/4-grooved main bearings, clearances run slightly larger but do not exceed the top end of the range.

Oil Pumps

There is one thing that cannot be said enough about high-volume oil pumps in a Buick engine: be very careful if you choose to run one. High-volume pump kits can damage your cam bearings if you use the wrong relief spring. Do not use the 60-lb spring (typically the red spring), because it is wound too tight. The coils tend to stick and bind before the relief valve can fully open, causing your pump to build oil pressures well over 100 psi. This high-pressure oil will cause your cam to float in the bearings, knocking on and destroying the bearings.

This TA Performance oil pump kit makes rebuilding the oil pump much simpler.

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/ how-to-upgrade-the-oiling-system-in-buick-engines/

Here the stock oil pump gears are compared to the high-volume pump gears. The 350 high-volume pump gear is the same size as the 455 stock gear (shown to the left). While most builders shy away from the high-volume pumps in big-block engines, the 350 readily accepts the high-volume pump with no issues. The gears on the right are stock 350 gears.

Most builders recommend a rebuilt oil pump with a minimum of 60 lbs. of pressure. An adjustable oil pressure regulator can supply this amount of pressure. If your tolerances are a little loose or if the engine will be spinning over 6,000 rpm, a high-volume pump is a good idea, but a stock pump will do the job. That said, the 350 does not have the same issues with high-volume oil pumps. In fact, the 350 high-volume pump gear is the same size as the stock 455 pump gear. For our 350 build, we chose to run the stock pump with a booster plate in the timing cover (this will be discussed in the next chapter). When assembling the oil pump, the end clearances should be kept to 0.002 to 0.003 inch. Once the oil pump is assembled, it should be packed with Vaseline or assembly lube. If this step is skipped, the pump will never prime.

The red spring on the left is the 60-psi high-volume spring. If you use this spring in a street-driven engine with the correct tolerances, the cam bearings will be destroyed from too much pressure. This spring can develop over 100 psi, which is just too much.

The pump build begins by refinishing the oil filter cover with a surfacing job. Lightly sand the cover with a piece of 220-grit sandpaper to even up the surface.

Check the end clearance once the pump gears are in place. There should be no more than 0.002-to 0.003-inch clearance. If the clearance is more than that, install high-volume pump gears.

The inner clearance must be checked, too. The gears require a clearance of 0.004 to 0.005 inch. If the clearance is 0.007 inch or more, then the timing cover is beyond specification and needs to be replaced.

With everything in check, the pump needs to be packed with either Vaseline or pre-lube.

If the pump is not packed with lube, it will never prime, leaving the engine completely without oil for the initial start up.

The oil filter housing was reinstalled and tightened down. An externally adjustable oil pressure regulator can be installed at the large hex-head bolt on the front of the filter housing.

If you are swapping a set of 400 or 430 heads to a 455 or converting a 400 or 430 block to pushrod-style rocker arm oiling, the oiling hole shown needs to be blocked. If you are running an early block, this can be accomplished with a 3/8-inch x 16 set screw. If you are running a 455, block the driver side only; block both sides for a 400 or 430 block.

The neoprene rear main seal is an important upgrade to the block oiling system. The stock-style rope seals simply do not work as well.

Do not leave out the factory windage tray. This tray prevents the crank from whipping the oil into a foam, and it keeps the oil from splashing on the crank and robbing power.

When using a high-volume oil pump in a 455, Jim Burek, Performance Automotive Enterprises, recommends breaking in a new engine using the stock oil–pump pressure relief spring. This 40-psi spring should be good for 60–70 psi (with a high-volume pump) at the 2,000–3,000 rpm break-in speed you will run the engine. This allows the engine to be safely lubricated and not go overboard on the oil pressure. One hundred psi would put too much strain on the fresh bearings and can destroy the distributor gear, cam gear, and front cam bearing. If you see the oil pressure falling off, you can always swap in a bigger spring. A 30–40 psi oil pressure level is plenty at the low break-in speeds. If you don’t have a stock spring and are planning on running the big pressure spring (typically red), you can trim down the lower-pressure spring by 1-1/2 coils, which will yield excellent pressure when the engine is warm. Also, if you find that you need the big spring to make enough oil pressure, you have a serious problem. Too much bearing clearance or a heavily worn timing cover is the likely culprit, and the engine needs to be torn down. The same approach effectively remedies low pressure problems in the 350 and V-6 turbo engines. The oil-pump pressure relief springs are shorter, but use the same principles.

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/ how-to-upgrade-the-oiling-system-in-buick-engines/

Euro Muscle — A Unique 1972 GSX

Dutchman Robert Noeken has a particular fancy for American classics. Purchased by Noeken in 2004, this 1972 GSX clone currently resides in the Netherlands. Jim Burek, of Performance Automotive Engines, El Paso, Texas, built the engine. It is a 455 stroked to 464, backed by an SP400 transmission. Noeken enjoys drag racing the car at Explosion race events, the car has been featured in a Dutch car magazine, and it has appeared in a Dutch TV show. This street-driven Buick runs as good as it looks. Time slips show 11.74 best quarter-mile ET. This GSX has won numerous Dutch OSL (Operation Street Legal) street racing trophies. The GSX trim package includes hood tach, front/rear spoilers, and correct decals. By the end of the 2005 season, the GSX won 4th place in the OSL championships and an 11th place in the Explosion championship.

The 455 was stroked to 464 ci and built by Jim Burek of Performance Automotive Engines. The engine features ported Stage 1 heads, 11.5:1 pistons, and a Poston intake.

Robert Noeken’s 1972 GSX clone has a storied history. The car was shuffled between various owners while Robert was trying to get his hands on it. He finally managed to purchase the car and had it shipped to the Netherlands, where it has been shown, cruised, and drag raced. The GSX even landed a part as the “meanest street racer” on a Dutch TV show.

Equipment Package:
• Jim Burek-built 464-ci V-8
• Stage-1 ported heads,
• Ross true 11.5:1 coated pistons and bearings
• Block O-ringed
• Deep sump oil pan
• MSD ignition
• S-divider lightweight aluminum intake
• Lunati cam; duration 251/273 at 0.050 inch
• Holley 850 DP carburetor
• Aluminum two-core radiator
• High-torque starter
• 2-inch Jet-Hot coated T/A headers; 3-inch full aluminized exhaust
• 3:73 12-bolt strong rear-end with C-clip eliminators
• Strange yoke
• 33-spline Moser axels
• LPW axel tube brace and LPW girdle
• Jim Burek-built T400 Switch-Pitch transmission and converter
• B&M shifter
• 6-point roll cage
• Factory bucket seats, console, and tilt column
• Front disc brakes
• Fiberglass hood
• Front and rear Koni drag shocks

The street-driven GSX runs 11.74 seconds in the quarter-mile, and this mighty Buick beats tuners and Euro-sport cars on a regular basis.

Nailhead engines used several oil pumps. The early 264 and 322 had beveled gears and different pickups. Top Nailhead builder Russell Martin recommends using the 1955–1956 pump in the 264 and 322. “I don’t think the beveled gears in the early oil pumps were better, just more expensive to manufacture,” Russell tells us. The 1957–1958 364 used an oil pump with a vacuum pump on it for wipers; a 1959–1961 oil pump eliminates the extraneous function. The 1962–1966 engines use one pump but have two different pickups, one for center sump and one for rear sump pans.

A really trick mod is to add a rear oil pressure gauge to the engine. By removing one of the rear freeze plugs (shown here), the oil pressure sending unit can be added with 90-degree elbow.

Rear Oil Pressure Gauge Installation

It is common for a Buick to show 4 to 5 less psi at the rear of the block than at the front. The trouble is, the stock oil-sending unit is located at the front of the block. There is a quick and easy way to add a rear pressure sensor so you can monitor the oil pressure at the rear of the block, or run two gauges and monitor both.
There are two ways of performing this task; one is a little more involved than the other. I prefer the following easier version. There are two pipe plugs at the back of the block, just above the freeze plug behind the cam. Remove the passenger-side plug. Install a 90-degree elbow that has 1/4-inch pipe threads on one side and compression fitting on the other. Be sure to wrap the threads with Teflon tape or other thread sealant. While you could use a copper capillary tube, the best feed line is a 1/4-inch braided line. This ensures the line will flex with the engine and not kink or break over time. Attach this line to the fitting. Drill a small hole in the rear of the engine, either up through the top, at the flat pad behind the intake, or to the driver’s side. Run the line through the hole and secure the line with a little silicone sealant to hold it in place. If done correctly, there will be plenty of clearance for the flywheel/flexplate. If you choose to run dual gauges, you will be able to monitor the pressure difference. If there is a substantial difference (10 psi or more) you can shut it down before any serious damage occurs.

Oil Pans

The 455’s stock oil pan is suitable for any street-driven engine, provided it does not rev past 5,500 rpm. When the engine starts spinning faster than 5,500 rpm, the oil pump often drains the pan, resulting in oil starvation. Some builders suggest that any Buick-powered car running 13s or less in the quarter-mile needs a 7-quart oil pan. Depending on your engine and how you plan on using it, there are a couple of choices. TA Performance and Poston Enterprises offer several oil pans that accommodate the 7- and 8-quart capacity and add some extra features (we will discuss these in the race engine section). Stef’s Fabrication Specialties offers a 6-quart aluminum oil pan designed to fit the Buick A-body (Skylark/GS) and maintain proper oil control. TA Performance also sells a larger capacity deep sump sheet metal oil pan for the big blocks.

Next, drill out the rear webbing (marked by the pointer) on the block to pass the line through. You should use a rubber or plastic grommet on this hole to protect the capillary tube or wire coming from the sending unit.

Welding the two pans together to create a larger pan is the last option. This is a good choice if you need the extra capacity for an engine up to 600 hp but don’t need the girdled aftermarket oil pans that can cost well over $500. Just be sure you use a good welder who is capable of stitching together thin sheet metal without burning it. This is also the only option for a 350; even Buick specialists do not make a bigger pan for the 350.

Motor Oil Considerations

Standard motor oils are not efficient enough to adequately cool and lubricate a high-performance engine, especially a Buick. That’s not to say that Buicks require ultra-expensive oil, but with their inherent oiling issues, truly high-performance oils are the best way to go.

MotorHead Classic heavy-duty oil is one of the best oils for a Buick. It has high concentrations of the anti-wear chemicals needed in older engines. Choosing the right viscosity is also very important. The thinner 5W-30 oils used in late-model engines will not have sufficient viscosity to shield your older, high-compression, larger-tolerance engine. Buick engines need heavier weight oil, such as 20W-40 or 20W-50, with the colder climates using 10W-40, for adequate lubrication. In addition, if you are running a mechanical non-roller cam, you will need oil with significantly better anti wear characteristics to keep your engine properly lubricated. Mechanical camshaft engines require racing oil with high levels of anti-wear additives, such as phosphorus and zinc. Some builders even suggest using four-stroke 20W-50 motorcycle oil. These oils have the correct chemistry and are safe for use in high-performance applications. Here is a trick: If you smell the oil and it smells a little like gear oil, then it probably has enough anti-wear chemistry and stabilizers to be sufficient to run in your big Buick.

For the blow-dried engines (we’re talking turbos here), the same types of oils are recommended. As an added bonus, you might try a little extra oil additive, like Lucas or Pro Blend. These add a little more stabilization that is needed for the high heat transferred to the oil by the turbo.

The 3.8-liter V-6 turbo engines use oil coolers to help remove the extra heat induced in the oil from cooling the turbo. Keeping the stock oil cooler clean and operating at its maximum capacity is paramount to keeping these high-powered engines cool. Better yet, upgrading the factory oil cooler to a high-performance four-core unit is a wise choice. The excessive heat generated in these engines has to go somewhere, and you certainly do not want it in the crankcase.

Street engines can benefit from a 7-quart oil pan. This stock steel pan has been modified to accept an extra quart of oil. The pick-up tube is constantly immersed in oil, even under heavy acceleration and cornering.

Choosing the right oil is a very important decision. This Royal Purple oil is specially formulated for high-performance and race engines. It has the right levels of zinc and other high-wear additives that are crucial to high-

Written by Jefferson Bryant and republished with permission of CarTech Inc

This Tech Tip is From the Full Book, HOW TO BUILD MAX-PERFORMANCE BUICK ENGINES. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this post on Facebook Groups or Forums/Blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https:// musclecardiy.com/ how-to-upgrade-the-oiling-system-in-buick-engines/

The post How to Upgrade the Oiling System in Buick Engines appeared first on Muscle Car DIY.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/automotive-engine-performance-coatings-and-treatments/

Current coatings on the market deliver enhanced thermal control, improved lubrication, and oil-shedding. Depending on the type of coating and the area in which the coating is applied, the benefits can include increased power, component durability, or both.

This group of parts helps to illustrate heat barrier and anti-friction coating applications. The examples shown here include high-temperature thermal-barrier coatings on head chambers, piston domes, turbo housing, and headers; anti-friction coatings on skirts, valvestems and bearings; and heat-release (or shedding) coatings on valvesprings. (Photo Courtesy Swain Tech Coatings)

Coating Types

Suppliers typically offer four types of coatings for high-performance engines: low-friction, oil-shedding, thermal-barrier, and heat-emitting. Each has its own set of parameters for use.

Thermal Barrier Coatings

Also called ceramic coatings, they act as a shield to prevent heat from passing into a part. For instance, a thermal barrier coating on a piston dome prevents combustion heat from being lost beyond the dome. This prevents heat from dissipating through the dome, causing the piston to expand. If there is a barrier coating, combustion heat is greatly reduced, and does not sink into the piston and cause expansion. Since the piston doesn’t expand as much you can then run a tighter piston-to-wall clearance.

The set of pistons in this shot have had only the domes treated to a ceramic thermal barrier coating.

Precoated engine bearings, that is rod bearings, main bearings, and cam bearings, are now available already coated from various bearing manufacturers.

If the combustion chambers are also coated, combustion heat stays in the chamber and promotes more efficient use of thermal energy. To aid in this, the valve faces can also be coated to help seal the heat in as well as to prevent excess heat from traveling up the stems.

If the exhaust path is coated, combustion heat is contained inside the exhaust path. This prevents loss of thermal energy and adjacent areas from being subjected to excess heat. Coating the exhaust ports and outside of the exhaust manifold also creates a scavenging effect, contributing to more-efficient exhaust flow. In essence, the combustion energy and heat stays in a more-contained path, doing its job, instead of being allowed to sink into surrounding areas, where it does nothing but waste energy.

Anti-Friction and Oil Management Coatings

Anti-friction coatings provide a low coefficient of friction between two moving surfaces and serve to retain surface oil between moving parts. This oil is applied to components, such as bearings and piston skirts. It’s exactly what you want at bearing and skirt locations.

Oil-shedding coatings provide a slick and non-porous surface treatment to aid in slinging oil off a component. A shedding coating applied to connecting rods and crank counterweights prevents unwanted oil weight from clinging to the surfaces. As a result, parasitic drag is reduced as the rotating assembly whips through the air and a mechanical advantage is realized.

In addition to piston dome coating, the same high-temperature heat-barrier coating may be applied to the combustion chamber, all valve faces, exhaust valve throats, and exhaust valve ports. This completely encapsulates the combustion stream path. (This head was coated by Dart.)

MAHLE Clevite, for example, uses a polymer-based moly-graphite coating on its performance bearings.

An oil-shedding coating is extremely useful for crankshaft counterweights, allowing oil to more quickly depart from the counterweight surfaces. This reduces the drag that exists because of clinging oil, which in turn reduces parasitic power loss.

An oil-shedding coating applied to connecting rods serves the same purpose: to reduce parasitic power loss caused by unwanted oil clinging to the surfaces. After all, the engine doesn’t need oil on the exterior surfaces of the crank and rods for lubrication, so by promoting oil departure from these surfaces, we reduce unnecessary drag, which helps to free-up horsepower from the rotating assembly.

Oil-shedding coatings also prevent hot oil from clinging to the stationary wall surfaces, and this helps reduce radiated heat, promoting much faster drainback to the sump. Interior walls include roof of valve covers, oil pan walls, (some) dry sump pans, and the underside of V-type engine intake manifolds.

A thermal-barrier coating can also be applied to the cover exterior. This coating combination helps to reduce radiated cover temperature while preventing oil from clinging to the cover roof and walls, allowing oil to scoot back to the moving parts where it’s needed.

The oil pump is an often overlooked but vital component. Applying an oilshedding coating to the oil pump gears and passages allows the pump to more efficiently move oil, which reduces the amount of oil that clings to the passage surface areas. An oil-shedding coating lets oil move through the pump faster and reduces the amount of oil that hangs around by sticking to passage walls.

Heat-emitter coatings promote the release of heat. Common applications for this specially formulated coating include valvesprings, with the coating intended to prolong spring life.

Piston Skirt Coatings

The moly coating’s true benefit is reduction of friction, which prolongs part life and reduces operating friction, and it naturally frees available horsepower. A moly skirt coating is not specifically designed to reduce heat, but because it reduces friction, heat is potentially reduced as a direct by-product. A moly skirt coating improves cold-engine startups; the moly coating prevents skirt scuffing that might otherwise repeatedly occur in that situation.

Many approaches can be used to reduce friction with the cylinder bores, including synthetic oils, plasma-moly ring faces, oil retention grooves in the skirt areas, plateau cylinder-wall finishes, etc. All of these methods have merit, but so does coating the piston skirt areas with a long-wearing high-lubricity material.

All of the coating shops offer thermal barrier dome coating and anti-friction skirt coatings. Here’s an example of a piston treated with a thermal barrier coating on the dome and moly-coating on the skirts.

Commonly, this is a molybdenumbased application applied to the skirts in an average thickness of about .0005 inch per side, which might provide about a .001 inch increase in piston overall skirt diameter. Since the moly is applied in such a thin layer, no additional bore-dimension changes are required. In other words, you should hone the cylinder to the size dictated for proper piston-to-wall clearance for a non-coated piston. Whether you’re installing non-coated or coated pistons, the finished bore size is identical. Do not compensate for the added moly coating when finishing your bores.

Forged piston applications typically run a .005- to .006-inch clearance, which does not change if you opt for moly-coated pistons. If you plan to use hypereutectic pistons that require a .001- to .0015-inch clearance, for example, finished bore size is not enlarged to compensate for the coating layer. With hypereutectics, the skirt coating might actually create what first appears to be a near-interference fit of the piston to the bore. This is not a concern because any excess moly is sacrificed during initial runs, and mixes with the engine oil in a completely compatible fashion. So install and run them. If you overhone by .001 inch in an effort to compensate for the moly coating, you simply defeat the benefit of the tighter and more efficient clearance.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/automotive-engine-performance-coatings-and-treatments/

Coating Sources

Many engine bearing manufacturers offer anti-friction coatings as standard or as an option.

Mahle Clevite offers its TriArmor engine bearings already coated with a moly-graphite treatment in a low-friction PTFE polymer base.

Dart Machinery has a full array of coatings, including moly-based anti-friction coatings, synthetic ceramic and traditional aluminum-based thermal barrier coatings, oil-shedding polymers, molyTeflon coatings for bearings, Teflon-based air-enhancement coatings for intake ports, etc.

When you have exhaust ceramic-coated headers, pay attention to the collector area. If the header has a bolt-on flange, there’s no need to mask off anything. However, if the collector has a slip-on end, ask the coating shop to mask off a sufficient area, since the thickness of the coating can result in a too-tight slip-on fit. (Photo Courtesy Swain Tech Coatings)

Ceramic thermal barrier coating is ideal for turbocharger housings. This increases efficiency and helps to reduce underhood temperatures. (Photo Courtesy Swain Tech Coatings)

Dart’s coating offerings include the following:

• DCIMOS2TeflonSkirtCoating
• DC2 High Temperature Reflective Heat Barrier for thermal barrier applications on piston domes, combustion chambers, valve faces, exhaust ports, etc
• DCB-3 Engine Bearing Coating (a moly/Teflon based material with highload/non-stick properties for bearings
• DC-4 Lubricating Pigments for wear and load capacity in applications such as valvesprings, oil pump gears, valvestems, timing gears, camshafts, and other friction related areas
• DC-5Oil Shedding Coatingfor shedding parasitic oil from connecting rods, crank counterweights, windage trays, inside oil pans and valve covers, etc
• DC-7 Anti-Corrosive Protectant to protect surfaces from weather, gasoline, alcohol, nitro methane, brake fluid, etc.

In a turbo application, according to Swain Tech Coatings, a heat-emitter coating provides benefit to an oil-cooled, bearing turbo. A stellite coating on the turbo impeller shaft (which can experience 1,650 degrees F) reduces shaft wear and acts as a solid film lubricant while providing the needed hardness to protect the shaft.

Swain offers three different thermal barrier coatings, including the standard thermal barrier coating (TBC), Gold Coat, and White Lightening. TBC is used in most applications for piston domes, combustion chambers, valve faces, exhaust valve backs (radius), and exhaust ports. Where higher temperature extremes are encountered, such as in nitrous oxide or turbocharged applications, the Gold Coat version may be applied, which simply yields a higher thermal-barrier capability for these extreme situations.

Cryogenic Stress Relief

This process stress relieves a crankshaft, reduces the chances of warping an aluminum head, and prevents distortion in a block bores.

Cryogenic treatment involves freezing engine parts to make them stronger. The tool-and-die industry regularly uses this approach to temper and extend the life of steel tooling components.

Cryogenic metal tempering requires a specialized, computer-controlled cryo tank that uses liquid nitrogen, in which components are exposed to temperatures at approximately –400 degree F. The pieces are cooled in a slow, controlled manner, then allowed to come back to ambient temperature in a controlled process. The engine block in this photo was removed from the tank only for the photo. Notice the white frosty surface, resulting from the frozen part exposed to room temperature.

What Does It Do?

In a nutshell, cryogenically tempering (deep-freezing) a metal part, makes the internal structure more uniform, more durable, and stronger.

The process of cryogenic freezing changes the structure of the metal being treated. Inside the metal, areas of weaker, potentially brittle deposits called austenites may exist. These are flaws that create the potential for cracking. Cryogenics changes these areas into harder, more uniform martensites. The process also creates a vast distribution of very fine carbide particles throughout the metal.

The Cryogenic Unit

Advanced Cryogenics uses the –300 Cryo-Processor, and has conducted an enormous amount of research in the field of cryogenic tempering of engine parts. For purposes of R&D, Advanced Cryo maintains its own test car, a modified D.I.R.T. race car with a Chevy big-block 467-ci bowtie engine. The block is .060-inch over, fitted with Chevy aluminum heads and produces a compression ratio of 13.5:1 and a dyno output of 650 hp. The engine runs on alcohol and lives at 7,200 rpm.

A wide range of components can benefit from cryogenic tempering, including blocks, heads, rods, cranks, cams, rockers, and brake rotors. (Photo Courtesy 300 Below)

“When we began the testing program with this motor,” noted co-owner Joe Troya, “Constant attention to valve lash adjustment was needed. After the entire engine assembly was cryo’d, we’ve noticed that cylinder and ring wear have been dramatically reduced, and lash adjustments are almost a thing of the past; everything stays so much more stable.” In addition to the engine block, heads, and all internal parts, the Advanced Cryo team has also started to treat and test the car’s suspension and brake parts in the same fashion.

In all, the Advanced Cryogenics’ race testing program has involved the treatment of some 15 engines, in D.I.R.T., Busch Grand National, NASCAR, and a few SCCA road racing applications. They’re also performing cryo testing for a few aftermarket engine parts manufacturers.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/automotive-engine-performance-coatings-and-treatments/

Benefits

Cryogenic treatment finds internal flaws missed by external Magnaflux bench detection. However, an internal pocket flaw may actually cause the part to snap open during freezing. Certainly, most engine builders agree that it’s better to find a bad part during testing rather than discovering the problem in a running engine. In other words, if the part is badly flawed, this process may break it.

With this process, the tensile and ductile strength of the part is improved, an obvious benefit for items such as connecting rods and head bolts. Cryogenic treatment also improves the bond of a weld, by producing a more uniform metallurgy structure.

Since this treatment stabilizes the metal, it reportedly improves the machinability of the part. It is a one-time, permanent process that changes the metal structure throughout the part. Once a part has been cryogenically treated, there’s no surface layer to break through during future machining. The only materials that don’t benefit from Cryogenic treatment are plastics (fiberglass, ABS, various composites) and engine bearings. “The process doesn’t hurt those parts, but it just doesn’t seem to help either,” says Troya. He’s treated blocks, heads, pistons, rings, cams, lifters, valves, pushrods, connecting rods, valvesprings, head bolts, retainers, crankshafts, flywheels, and even frozen spark plugs.

The electrical conductivity of the plugs was increased measurably as a result of the process. “The go-kart guys really notice the difference,” he noted. Although the process creates a slightly higher Rockwell hardness, that isn’t the real directive. Cryogenic processing benefits a part by stabilizing the metal structure, creating a stronger molecular grain pattern throughout the metal.

Vibratory Stress Relief

Vibratory stress relief involves inducing a controlled series of vibrations to metal components (in this case, engine components). This process provides an effective and non-destructive method of achieving stress relief, which results in longer life and increased component stability. Bonal Technologies (to my knowledge, the only provider of this technology) designs and manufactures a complete system for subharmonic stress relief.

Two forms of stress can exist within a metal part: mechanical and thermal. Subharmonic vibratory stress relief (VSR) is a method that relaxes metal (commonly known as Meta-Lax), but only for the metal part’s thermal stress, leaving the mechanical stresses unchanged.

Vibrating a part relieves any stresses that were created due to the heat involved in welding, casting, machining, or forging, but it does not alter the metal’s strength.VSR doesnot generate heat and doesn’t alter the part’s hardness. As a result, VSR is safeto use on a repeated basis.

How It Works

Let’s say that you have a part rated with a strength of 50,000 psi. Because of internal thermal stress that may be present, the actual strength of the part might be reduced by 20 percent (for example). If the part is heat relieved in an oven, the internal stress is relieved but the part might now only offer a strength of, say, 45,000 psi due to the softening created by the heat. (In contrast, VSR removes internal stress while maintaining the metal’s full 50,000-psi strength.)

The vibration process searches for the harmonic peak of the workpiece by vibrating it. The peak is where the piece tends to create the maximum harmonic disturbance, just as a tuning fork vibrates when subjected to a force or a fishing rod whips and vibrates when dynamic force is present.

The vibration process searches for the harmonic peak of the workpiece by vibrating it. The peak is where the piece tends to create the maximum harmonic disturbance, just as a tuning fork vibrates when subjected to a force or a fishing rod whips and vibrates when dynamic force is present.

As a harmonic disturbance is sent through the workpiece, those signals are sent back to the system’s controller (via the transducer). The force inducer is then automatically adjusted to vibrate the workpiece in a frequency range that begins just before the peak. This energy area at the base of the peak is where maximum energy dampening occurs. Sending these adjusted (or tuned) vibrations through the workpiece removes stress.

According to Bonal Technologies’ president, Tom Hebel, “We first find the harmonic peak to establish where the subharmonic area is. We then induce vibration at that frequency until the part stabilizes. It’s as though the part tells you that, up to a point, it can dampen the vibrations on its own; but beyond a certain point, it can’t. This process shifts the harmonic peak to its natural location, from an artificial frequency to a stress-free frequency.”

Conventionally, if you find the harmonic peak, you might add weight to dampen that vibration. With VSR, you relax the metal in order to alter the harmonics that can take place. Thin of a stressed engine component as a musical instrument that’s out of tune.VSR brings the part back into tune.

Benefits

Hebel cited a simple experiment that helps to illustrate the benefit of VSR: “A local industrial machine shop was curious about the concept, so we performed a demonstration using a solid aluminum bar, 2 inches in diameter and 36 inches long, supplied by the shop. They cut the bar in half (two 18-inch sections). We Meta-Lax treated one section only. The shop then machined each bar section on a lathe, by exactly the same amount.

“Each section was then measured for distortion. The untreated section distorted (warped) by .020 inch along its length, while the treated section moved a mere .002. The dramatic increase in metal stability was obvious.”

Thermal stresses can also be induced as a result of distortion immediately after grinding, welding, or machining. This creates a tendency to prematurely crack. Hebel advises that the optimum time to vibrate the part is immediately before the final machining phase (just before the last task that could cause distortion). All four types of stress relief (heat treating, cryogenic freezing, vibratory relief, and natural seasoning) address the issue of thermal stress. VSR offers an advantage because it’s faster and doesn’t affect mechanical stresses. You already know that a stress-relieved part distorts less during use. When a relieved part is trued during machining, it tends to retain this trueness. For machining advantages, the process reportedly reduces machining time and reduces distortional effects during machining.

If the part distorts less during use, wear is reduced and engine efficiency is enhanced. A quality stress relieving helps to keep bores round and decks flat, something that every performance-engine builder strives for, and is central to the blueprinting goal.

How to Use It

A VSR system includes a force inducer (this unit attaches to the workpiece and applies the vibrations), a transducer (this sends a feedback signal from the workpiece to the control computer), and a control console unit (computer). System prices start at around $7,000 and can climb as high as $35,000, depending on size and application. Some controller units offer an analog readout, while others provide digital information and a hardcopy plotting printout. The object is to transmit the programmed vibrational forces to the engine part(s).

This stress relief system can be used on-site as a portable setup, or in the shop as a permanent fixture. The force inducer can be attached directly to the piece being treated. For example, the inducer can be clamped to a bare engine block, or even a complete engine assembly, while on a stand or even in the vehicle. As a non-portable shop system, the workpieces are clamped to a heavy steel-platform table.

If a number of parts are to be stress relieved at the same time, all of the parts can be mounted to the precision steel table. A block and cylinder heads can be bolted to the table, and smaller items such as a crankshaft, connecting rods, valvesprings, etc. can be secured to the tabletop by means of accessory brackets and clamping fixtures. As long as the vibrations can be transmitted to the engine parts (by direct attachment to the force inducer or by being rigidly mounted to the tabletop with the force inducer secured to the table), the vibrational force is able to affect the engine parts’ metallurgy.

Portable systems have been successfully used by race chassis builders. While a race car tubular chassis is being welded, or even after welding has taken place, the portable force inducer is bolted to the chassis. The resulting vibrations stress relieve the tubular network, reducing the chance for frame fatigue and failure. Portable setups have even been used at race sites on completely assembled engines.

Hard Cylinder Coating

This is an application of an optimized deposit of dispersed nickel and a uniform inclusion of hard silicon carbide particles, known today as Mahle’s patented Nikasil.

According to Mahle, with a roughness average of 15 Ra, typical Nikasil-coated cylinders can operate at higher temperatures with less wear. This allows clearance from cylinder wall to piston to be optimized to better control oil consumption with lower ring tension, for a reduction in friction. This coating also provides superior heat conductivity and allows increased oil retention during cold starts.

Benefits

The performance benefits of the Nikasil coating include low wear rate, low operating noise, thermal consistency, and faster ring break-in. When selecting honing stones, the rule is: the harder the cylinder surface, the softer the bond of the stones.

Nickel is oilafilic, which means that oil is attracted to it, resulting in a constant oil layer. Another benefit is Nikasil’s uniformity and repeatability. For teams with multiple engines, this greatly reduces any variances between cylinders and between engines.

Nikasil and similar coatings are electro-deposited. Ceramic coatings are similar. For example, Perfect Bore uses a 16-percent silica-carbide particle in the 2- to3-micronrange,with a balanceof nickel. A number of engine builders are seeing their work run two or three races without the need for honing during a freshening rebuild, with only the need to merely run a silica carbide brush for minor touch-up. Some engines have run several thousand race miles without being rehoned.The current trick is to hot hone to minimize bore distortion to eliminate potential blow-by.

For racing applications, this hard coating provides the opportunity to run tighter wall clearances. Wear resistance is higher, cylinder wall lubricity is better, and wear is minimal. In a Winston Cup engine application, a cleanup of only .0002 inch might be required following a grueling 600-mile race, allowing even the original rings to be reused.

These hard coatings really don’t offer a performance benefit in terms of gaining increased power. The benefit lies in being able to run tighter clearances and a substantial gain in engine longevity.

Honing the Coating

According to extensive research conducted by Sunnen Products, Nikasil-coated cylinders should be honed with diamond stones. Hard cylinder coatings can be applied to the bore (in iron and alloy blocks), but coated cylinder liners are more popular. If the bores have been coated and now must be recoated as a result of wall damage, the block must be shipped away, which eats time. Coated liners allow the engine builder to much more quickly refresh a block in his shop.

With chrome coating, it is more likely to hone through the chrome (potential of fracturing of the plating) due to any distortion of the cylinder in the areas adjacent to the head bolt areas, even with a dry torque plate. Nikasil and similar coatings don’t share this potential problem since they’re not as brittle as chrome.

The force inducer generates the vibrations that are transmitted to the work piece. This inducer is clamped to a steel worktable upon which the parts are secured.

Nikasil, on the other hand, is very consistent for thickness and hardness uniformity. Because Nikasil allows tighter clearances and its oil retention is much higher, you can get away with creating a smoother finish. Typical Nikasil cylinder finishes are in the Ra range of6 to10.

Rings

It’s absolutely critical to use the correct type of rings in conjunction with Nikasil-coated cylinders. The top ring is typically moly or PVD; the second ring is ductile iron. Chrome rings cannot be used (including oil control rails) because chrome and Nikasil react to each other and result in scuffing. So just run plasmamoly top rings, ductile-iron second rings, andunplatedoilrails.Ringseatingoccurs very quickly. Nikasil and other cylinder coatings are applied to aluminum or iron walls (on parent bores or on liners).

Typically, the coating is about .008 inch and can be sprayed on between .012 and .015 inch thick. This type of coating visually appears to be chrome, very shiny and difficult to scratch. In order to touch up Nikasil in order to re-ring, a 150-grit aluminum-oxide stone usually suffices, just to clean and remove any high points. However, if you find excessive wear or if new sleeves are to be installed, finishing requires a 500-grit diamond stone.

Cost

For a four-cylinder block, cost could typically be around $750 for coating the metal bores, or $200 per liner if you need sleeves. Coated liners for an eight-cylinder block may run about $1,600.

Nikasil and similar coatings are high-end processes for builders with the budgets to handle the expense. However, when you consider the reduced inventory required for blocks, cranks, rings, etc., and the extremely minimized need to re-hone, the initial investment quickly pays for itself.

Written by Mike Mavrigian and posted with permission of CarTech Books

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/automotive-engine-performance-coatings-and-treatments/

The post Automotive Engine Performance Coatings and Treatments appeared first on Muscle Car DIY.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-timing-systems-guide/

Chain Drive

Chain drives are offered in singleand double-tooth sprocket designs; double rollers are the preferred choice for any high-performance application. Relatively less expensive OEM systems often used aluminum or composite cam sprockets with nylon teeth to reduce noise. The nylon teeth, exposed to age and abuse (or both), can become very brittle and can fail, sending sharp bits of nylon into the oil pan sump. Basically, the nylon tooth setups are worthless for any engine that’s spitting out some respectable power.

Timing chains are made in two basic formats: links and bushings. The bushings eventually wear and create sloppy cam timing. Roller chains with rollers provide superior contact with the sprocket.

This is a double roller chain setup featuring a billet-steel cam gear. Billet cam sprockets offer increased strength, but considering the higher-than-cast cost, it really isn’t needed for stock or mild engine builds. However, it’s a sensible choice for a chain drive in high-horsepower applications. Note that this set has advance/retard changes of 2, 4, and 6 degrees. (Photo Courtesy Comp Cams)

High-quality chain-drive systems feature true rollers (not fixed bushings) that contact the sprocket grooves for reduced friction and longer life. Seamless rollers and precision-machined teeth/grooves are what sets high-quality high-performance chain drives apart from anonymous-brand kits. (Photo Courtesy Comp Cams)

Both single-roller and double-roller setups are available with crank and cam sprockets featuring single- or doubletooth rows. Double rollers offer more strength, less stretch, and more consistent timing. In some cases, you’re limited to using a single-roller chain due to timing cover clearance.

If you’re planning to use a chain drive to run your cam, go with a double roller. But be aware that it’s the quality of the materials and the design that counts. Roller chains may be made with seamed or seamless rollers. Seamless offer greater concentricity and greater durability. Avoid bargain-priced overseas junk and stick with a major brand such as Melling, Cloyes, Comp, etc. Cam sprockets may be made from cast iron, powdered metal, or billet steel. For the street, and for engines making fewer than 300 hp, the higher cost of a billet gear simply isn’t necessary. PM is stronger than you might think, and is used in many OEM high-horsepower engines. But if you’re dealing with a reasonably powerful build (500-plus horsepower), paying a few extra bucks for a billet setup makes sense. If nothing else, it provides more peace of mind. Always buy the highest quality that you can afford.

Belt Drive

Swapping from a timing chain to a belt drive provides the possibility to increase power. A belt drive has reduced frictional loss, theoretically more precise timing, and smoother valvetrain motion. A dry belt system also eliminates windage variables (compared to a timing chain and gears running in oil). A belt drive does a better job of isolating crankshaft torsional vibrations. It can be viewed as a second harmonic dampener for the rotating assembly because it absorbs a degree of operating harmonics.

You might assume that a belt stretches over time, but this isn’t a concern. Performance drive belts have substantial reinforcement to prevent stretch. If a belt fails, it is likely due to age.

An example of a belt drive; this one is a Jesel for big-block Chevy. The kit includes the backing plate, cam hub, bronze thrust washers, crank gear, and belt. The backing plate covers the front of the engine, sealing it off; the cam hub allows the cam gear to be mounted on the forward side of the cover. Cam timing adjustability via a two-piece cam gear offers +8/–8 degrees of change.

Comp Cams’ Number-6100 Hi-Tech belt drive. It’s a typical belt drive with a cover that seals off oil, achieving a dry belt design. (Photo Courtesy Comp Cams)

Comp Cam’s Xtreme Duty Hi-Tech belt drive (PN 6507) has a 1.250-inch belt for extreme cylinder pressures encountered in nitrous and blower applications as well as a belt idler. (Photo Courtesy Comp cams)

Belt drive systems offer rugged performance, accurate timing, quiet operation, and help to dampen harmonics. Aside from the relatively higher price tag (depending on brand and application, around $800 to $1,200), there’s really no downside to going with a quality belt drive system. Even Pro Stock racers use belt drives, and that is an endorsement.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-timing-systems-guide/

Installing a Belt Drive

Here I use a Jesel belt drive installation on a big-block Chevy application as an example. I installed this drive system onto a 632-ci build with a Dart Big M block.

The first step is to install a stock-type big-block Chevy timing cover gasket to the block face. I smeared a thin coat of RTV on both sides of a Victor-Reinz gasket for insurance (habit). Then I installed the Jesel aluminum cover housing. This cover is secured with six 1/4-inch x 20 socket-head cap screws, which I tightened to 50 inch-pounds.

Jesel supplies a handy spanner wrench to hold the cam steady during bolt tightening. Three 5/16-inch x 18 torx-drive bolts were supplied, as well as a handy T-45 torx bit. Jesel recommends applying a light coat of RTV to the three bolt threads. These torx bolts were tightened to 30 ft-lbs (Jesel’s range is 28 to 30).

With the cover mounted to the block, the cam hub is mounted to the cam. The kit includes a hub-securing tool to hold the cam steady while tightening the mounting bolts.

Bronze thrust washer(s) are installed at the hub to adjust cam thrust. The bolts’ threads are coated with RTV and torqued to spec.

A retaining plate is mounted; it has a seal at the cam hub. The thrust washer(s) is/ are located between the hub and retaining plate.

Alignment dots are found on both gears. The cam gear offers an adjustment range of as much as 8-degrees advance or 8-degrees retard.

Finish-installed Jesel belt drive. Since the belt runs dry and oil is sealed by the backing cover, the belt system can run exposed. This makes service for cam timing or cam swaps much easier.

Next I oiled a brass thrust washer (on both sides) and slipped it over the cam nose. This was followed by the cam nose adapter. For sealing purposes, a light coat of RTV was applied to the rear face of the adapter where it meets the cam nose face. Jesel supplies a handy spanner wrench to hold the cam steady during bolt tightening. Three 5/16-inch x 18 torx-drive bolts were supplied, as well as a handy T-45 torx bit. Jesel recommends applying a light coat of RTV to the three bolt threads. These torx bolts were tightened to 30 ft-lbs (Jesel’s range is 28 to 30).

Next I installed another brass thrust washer to the outside perimeter face of the adapter (oiled on both sides). The next step was to install the shim pack supplied in the kit. I installed all three shims (these are located over the six 1/4-inch x 20 studs on the face of the cover), followed by the seal-fitted shim cover flange. In order to avoid damage to the rubber seal, I first removed the small key from the cam nose adapter.

According to Jesel’s instructions, camshaft endplay should be .010 to .015 inch. The supplied shims must be added or removed in order to achieve a cam endplay of .010 to .012 inch. When I set up my dial indicator, I found endplay to be .017 inch. I called Jesel to ask their advice, and one of the techs assured me that .017 inch is acceptable.

With cam endplay verified, I removed the thrust flange and the three shims. I lightly coated all shims and the rear face of the flange with RTV and reassembled, using the supplied 1/4-inch x 20 nyloc jam nuts, tightening them to 50 in-lbs. With the shim pack and flange installed, I re-installed the small key to the cam nose adapter.

Next I installed the crank gear drive (I installed a pair of keys measuring .185 inch thick by .735 inch long and .300 inch high into the snout’s key slots). This is an interference fit, requiring an aluminum driver that slips over the crank snout driver, which was supplied in the kit. The crank snout had a slight step up in diameter. When the gear was slipped onto the crank and stopped with hand pressure it was then driven on another .384 inch (in this case) until it seated.

At this time, I rotated the crank to place the crank gear’s timing dot at 12 o’clock. The cam adjuster plate dropped over the four studs on the black cam gear and was assembled with the cam timing mark at the top, aligning with the center (zero) timing mark on the adjuster. I installed the cam gear and adjuster plate onto the keyed cam-nose adapter.

Next I installed the cam locking flange using the left-hand-thread bolt provided. It was snugged just enough to keep the cam gear keyed in place. With the four adjuster plate to cam gear nuts installed with about 11 ⁄2 threads, I tilted the top of the cam gear forward to slip the timing belt into place.

This took a few minutes because I needed to keep the timing dot on the bottom of the cam gear aligned with the top dot on the crank gear. The belt was a tight fit, so patience was definitely required. Once the belt was in place, I snugged the four 12-point nuts to secure the adjuster plate to the cam gear.

Once the timing belt was in place, with both dots aligned (cam gear dot at 6 o’clock and crank gear dot at 12 o’clock) and with the cam adjuster marks set at zero, I tightened the cam gear’s center left-hand-thread bolt to 70 ft-lbs (I needed a 12-point, 5/8-inch socket for this bolt).

I was then ready to degree the cam. Although the job seemed daunting at first glance, it actually wasn’t that big of a deal. Because the oil was sealed by the rear cover, the belt drive was exposed, making cam adjustment easy.

Gear Drive

The theory behind a gear drive is simple. Crank motion is directly transferred to the cam via a set of meshed gears. With no chains to stretch or wear out, gear drives provide superior and consistent cam timing. Gear drives are also stronger and last longer than the average timing chain set. Those are the pros.

The cons include potentially greater harmonics transmitted to the cam and (in most cases) a notable whine that results from gear engagement. The whine is somewhat similar to the sound created by a supercharger blower, which can be really cool or really annoying, depending on your frame of mind.

If you want a quiet engine (aside from the exhaust note, of course), you probably won’t like a gear drive. However, some gear drive manufacturers now offer a “quiet” version that produces less whine. Gear drives and related parts are available from Edelbrock, Milodon, BHJ, and others.

Gear drive with two idler gears. Gear drives offer accurate cam timing/drive, but can transfer more crank harmonics. Noisy and quiet versions are available. The noisy versions produce a gear-to-gear sound similar to a blower whine. This noise is matter of personal preference. (Photo Courtesy Comp Cams)

Edelbrock

You can replace a stock timing chain with Edelbrock’s Accu-Drive camshaft gear drive kit. This gear drive system transmits power from the crankshaft gear to a full-floating main idler, which drives the camshaft gear. A unique feature of this system is the ability of the main idler gear to float to an optimum position between the crankshaft and camshaft gears, ensuring absolutely equal load sharing between them.

The gears are made from billet SAE- 1144 steel with induction-hardened teeth. Gear teeth are shaved for precision operation. The set has hardened and ground idler pins from billet steel.

To install, just replace the stock crank and camshaft sprockets with AccuDrive gears and slip in the idler assembly. Most Accu-Drives require no modifications to the engine block, although some fitting of the axles and front cover may be required.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-timing-systems-guide/

Milodon

The gear drive system from Milodon has a three-gear setup with easy cam timing adjustment. All Milodon gear drives are three-gear, “fixed idler” models. The idler gear mounts solidly to the block (under cover) or to the cover (full cover). This system does not rob any power from the engine and (more important) does not allow cam timing to vary. The full-cover drive uses an adjustable cam gear and hub assembly to set cam timing, accessible through the removable cam cover. The cam itself is bolted to the hub.

The Milodon gear drive uses the cam gear and hub to advance or retard the timing. You simply unbolt the hub and turn it until the indicator mark is lined up with one of the seven bolt positions on the cam gear, with no offset bushings or keyways to mess with. The cam must be installed straight up (no advance or retard) as follows:

With no cam gear in place, locate TDC for the number-one cylinder using a degree wheel. Rotate the crankshaft until the degree wheel indicates the intake valve opening per the cam manufacturer’s specs.

Place a dial indicator on the intake valve and rotate the crank until the valve opens to the recommended checking clearance (usually .050 inch of lift).

At this point, the camshaft is now installed straight up with no advance or retard. Install the cam gear. Adjust for your desired advance or retard. Place a mark on the cam hub next to any cam gear bolt hole position and label that hole number-1. In a clockwise travel, label the remaining bolt holes two through seven.

You’re now ready to set cam timing. Each bolt hole has gear-tooth positions for advance and retard. The chart in the provided instructions shows the settings for each hole. To advance the cam, turn it clockwise until the indicator mark on the hub is lined up with the proper bolt. To retard the cam, turn it counterclockwise until the mark lines up with the hole you want. Tighten the hub bolts and your cam timing is set.

BHJ’s timing set length gauge. This specialty gauge allows you to check and/or determine proper chain or belt length for your engine. Mounting posts are adjustable to set your exact center-of-crank-to-center-of-cam distance. (Photo Courtesy BHJ Products)

Once the engine’s precise center-to-center distance is set, the timing system is placed in position with the dial indicator zeroed. Compressed air at 100 psi is applied, and the dial indicator is watched for +/–. Shown here is a chain drive check. (Photo Courtesy BHJ Products)

Belt drive check on the same length gauge. (Photo Courtesy BHJ Products)

BHJ

BHJ offers a timing set length gauge (TSG-1) that’s adjusted to the desired center-to-center distance using a micrometer and the setup pins or an optional setup standard. The dial indicator, included with the gauge, is then zeroed at the desired length. Timing sets can then be dropped onto the appropriate mounting plugs.

The TSG-1 requires 100 psi minimum air supply. Activating the air switch applies exactly 100 pounds of tension to the chain, as specified by leading chain manufacturers. The timing set length is read as a plus or minus dimension from the desired length on the dial indicator.

This precision measuring fixture eliminates the need to special order custom-length timing sets or waste time with tedious trial-and-error methods of obtaining proper timing chain fit.

TSG-1 accepts timing sets with center distances ranging from 4.125 to 6.125 inches, using the appropriate mounting plugs. The gauge includes a precision dial indicator, setup pins, and one pair of mounting plugs.

Also available is a timing set gauge made specifically for the Mopar R5 or the small-block Chevrolet using the Jesel belt drive. Additional mounting plugs and optional setup standards are available for all engines.

Ford small-block cam gears have one cam alignment dowel. Considering today’s high-lift cams and high valvespring pressures used with roller cams, this timing gear design really needs an upgrade for better timing control. BHJ makes a timing-set drilling fixture (PN TSDF-FOS) that allows you to add a second alignment dowel placed 180 degrees from the existing dowel location. This requires a simple three-step process that can easily be handled with a bench vise and hand-held drill (or on a drill press or milling machine).

The kit includes a fixture plate, end mill, drill, finishing reamer, drill bushings guides, and mounting hardware. This is a worthwhile and easy-to-perform upgrade if you’re running a nasty cam in your small-block Ford and plan to use a chain drive.

Written by Mike Mavrigian and posted with permission of CarTech Books

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-timing-systems-guide/

The post How to Blueprint Engines: Timing Systems Guide appeared first on Muscle Car DIY.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-balancing-guide/

Discussion about engine balancing is essentially referring to balancing the crankshaft. The factors that affect crankshaft balance include all of the rotating and reciprocating weight, so in order to balance the crank, you also need to balance the pistons and connecting rods. Rotating weight involves the crankshaft and the big ends of the rods as well as and the rod bearings. Reciprocating weight involves the small ends of the rods, the pistons, wrist pins, pin locks, and rings.

This Pro-Bal balancer features an overhead belt drive that contacts the crank’s center main journal from above.

When balancing a crankshaft, the common approach is to consider 100 percent of the rotating weight and 50 percent of the reciprocating weight. Overbalancing is an approach that considers a higher percentage of reciprocating weight. Instead of weighing only a single piston, a single rod, etc., take the time to weigh each component in order to weight-match all pistons and all rods.

Follow basic weight-matching guidelines (use the lightest piston as the reference and remove weight from all remaining pistons to match, etc.). Even when performing an internal balance, don’t assume that the zero-balance dampener or flywheel is in fact balanced to zero. Spin balance the dampener and flywheel independently as well, correcting it if needed. If, by chance, the dampener will be painted, spin it again after the paint job to verify that no severe paint-thickness inconsistencies are present that affect balance.

Engine balancing refers to balancing the crankshaft to accommodate the reciprocating and rotating forces that it encounters during operation. Reciprocating force is presented by the forces that go up and down and act upon the crankshaft centerline. This includes the weight provided by the pistons, piston pins, piston rings, and pin locks. The rotating weight attached to the crankshaft includes the rod big ends, rod bearings, and the amount of oil that clings to the rods.

Although the goal is to balance the crankshaft, you must first weight match the components that attach to the crankshaft. This means that each piston and pin must weigh the same, all rod small ends must weigh the same, and all rod big ends must weigh the same. Additional items such as rod bearings, pin locks, and rings are manufactured so consistently that by weighing a sample of each, you can assume that the rest weigh the same.

Once the pistons are weight-matched and the rods are weight-matched, a bobweight can be created, which duplicates the components that attach to the crankshaft. This bobweight is then secured to the crankshaft. The crank is spun on a balancing machine, and weight is then removed from or added to the crankshaft counterweights.

The goal is to eliminate unwanted forces at the crankshaft geometric centerline, creating a rotating and reciprocating package that allows the crankshaft to run as smoothly as possible.

Internal versus External Balance

Crankshafts may be balance corrected internally or externally. In either case the attached parts (pistons, rods, etc.) must first be weight-matched. When a crankshaft has internal balance, balance weight correction is performed on the crankshaft itself, adding or removing weight from its counterweights. This requires a zero-balanced dampener and flywheel. The dampener and flywheel for this example are designed with a zero balance, so neither affects crankshaft balance. This is one advantage of internal balance. The dampener and flywheel may be changed in the future without affecting crank balance.

When a crankshaft is designed for external balance, the offset-weighted dampener (or balancer) and weighted flywheel must be attached to the crankshaft during balance spinning. Corrections are then made by adding or removing weight at the crankshaft’s counterweights.

While a new aftermarket crankshaft may be near zero balanced at the factory, this provides only a starting point. Consider the mass of everything hung onto the crank: rods, rod bearings, pistons, wrist pins, pin locks, and piston ring package. Any crank must be balanced with rotating and reciprocating weight to create a balanced assembly package. Regardless of crank origin (OEM or aftermarket, new or used), the entire rotating/reciprocating package must be balanced. If at any point you change any of the mass-weight components from a previously running engine (such as pistons or rods), the crank must be rebalanced.

Two common types of crankshaft dampeners include the rubber/elastomer type and the viscous type. An OEM-style elastomer/rubber dampened balancer is designed to reduce crankshaft harmonics at a pre-engineered frequency range. A viscous dampener has a cavity partially filled with a viscous gel that is designed to maintain balance at all engine speeds.

If you are balancing an externally balanced crankshaft, where you need to include both the flywheel and dampener on the crankshaft during balancing, using a viscous dampener requires a different approach. Since the viscous dampener constantly works to maintain balance, this can mask slight crankshaft imbalance conditions. If the viscous dampener is designed for use on an externally balanced crankshaft, it was likely designed as a two-piece unit. Remove the viscous balancer ring from the hub and mount only the hub to the crankshaft during balancing.

Although some original equipment engines were designed for external balance, it is possible to internally balance any crank. The shop equipment required to perform crankshaft balancing includes: a professional-level digital scale, which is used to weigh individual parts including pistons, pins, rings, locks, rods, and rod bearings; a connecting-rod support stand used in conjunction with the digital scale; an electronic spin balancer designed for crankshaft balancing; an overhead drill press to drill holes into the counterweights; and a set of bobweights, which are used to simulate the weight of the pistons, rods, etc. Add a flywheel adapter hub to allow balance corrections to a flywheel that has been serviced or is in question.

Weight Matching

The first order of business is to determine the weight of the pistons and connecting rods. You need to know how much each part weighs, in order to create a bobweight card, and to make sure that all piston and rod weights are identical.

Your digital scale must be absolutely clean. Astute engine builders always keep a dust cover on their scales when not in use. The scale should also be located in an area free of moving air. These scales are so sensitive that a breeze caused by a nearby door opening can easily create a false reading.

After pressing the ZERO button to calibrate the scale, weigh each piston and label with a marker pen. With the entire set of pistons weighed, you then examine the set to look for variations. If weights do not match, the lightest piston becomes the reference point, so you remove material from the remaining pistons in order to match the lightest.

If weight must be removed, do this carefully to avoid compromising the structural integrity of the piston. With the piston secured in a dedicated piston pin vise, material can be removed (by milling) at the underside of the pin boss. However, today’s high-quality high-performance pistons are manufactured with such a high degree of precision that the need to perform weight correction is rare. When all pistons in the set weigh the same, record the weight of a single piston on the bobweight card.

Pin-to-Piston Weight

Next note each piston pin weight. Again, it is rare to find a set of quality piston pins that are not already weight-matched. You should not consider modifying a piston pin, but if any slight variation in weight is found with the piston set and the pin set, before attempting to remove weight from any of the pistons, you can try to match pins to pistons in an effort to correct any weight deviation.

By mixing and matching combinations of heaviest and lightest, you may be able to create piston and pin sets that create a closely matched combined weight. If so, then each pin must remain with its piston all the way to final assembly.

Each component (rods, rod bearings, pistons, pins, locks, and rings) is weighed on a precision digital scale. The first step is to place the weight of the on-scale stand on the scale and tare the scale. This will return the scale reading to zero with the bare stand to remove the weight of the stand from the equation. When weighing a rod big end, the rod must be mounted with the bore centers horizontal and parallel (note the bubble level on the rod big end). The small end is supported on a stand off the scale, while the big end is supported on a stand that rests on the scale.

Connecting Rod Weight

Next weigh each connecting rod. Place a specialty rod stand that accommodates the rod small end onto the digital scale and TARE (zero) it in order to ignore or negate the weight of this stand. Place another rod stand next to (but not on) the scale. This stand supports the rod big end. Each stand is adjustable for height. Mount the rod to the stands in a horizontal manner and adjust so that the big-end center is level with the small-end center. Note and record the small-end weight.

Then reverse the rod in order to weigh the big end. Again, the rod must be level. Rod stand designs differ; if a different stand or stand component now rests on the scale, the scale must again be TAREd to negate the weight of the stand. Record the big-end weight.

After recording all rod weights, compare and determine if weight correction is needed. Today’s high-quality performance aftermarket forged and billet rods are usually extremely well weight-matched, so chances are no correction is needed. Older-design OEM rods may have weight bosses at the small end and at the cap, allowing material removal. Today’s rods are typically free of these bosses, and you may not have any available excess material for removal.

If you have a set of aftermarket rods that are not weight-matched, you’re better off contacting the manufacturer to discuss the problem, which may mean exchanging for another set. Once all rods have been weighed and recorded, remove the stand from the scale and ZERO the scale.

Weigh and record one piston’s set of pin locks (if your pistons have full-floating pins). Weigh and record the weight of one piston’s full set of rings (including the oil ring support rail, if so equipped). Finally, weigh and record the weight of one rod’s pair of bearing shells.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-balancing-guide/

Bobweights

Bobweights have heavy-duty aluminum V-clamps that fasten together onto the crankshaft rod journals. Each side of the V-clamp has weights. One half of the total bobweight is placed on each side of the journal. Using the information recorded during component scale weighing, the bobweights are assembled on the digital scale to duplicate the determined weight. The total weight of the bobweight must match that of the bobweight card, which includes the V-clamps, adjusted weights, and nuts that secure the bobweight halves together.

The small end of the rod is weighed the same way as the big end. The on-scale support stand is first tared, and the rod is mounted horizontally.

Adjusting

The weight is adjusted by adding lead shot to capped barrels that attach to the V-blocks or by adding weighted discs onto threaded rods on the V-clamps (designs differ). To create a bobweight on a V-8 or 90-degree V-6, 100 percent of the rod throw’s rotating weight (the big end of the rod and the rod bearing) and 50 percent of the reciprocating weight is factored in, which includes the pistons, small rod ends, rings, pins, and locks. That means both rod big ends and both sets of rod bearings, but only one piston/ pin/ring set, is factored in for the reciprocating weight.

Each piston pin is weighed and recorded. Sets of pins generally weigh the same. However, if any small deviations are present, you may be able to mix or match lighter or heavier pins to pistons to create a piston/pin combination that provides a matching-weight set. This could reduce or eliminate any need to remove weight from pistons.

If weight must be removed from a piston, material can only be removed from an area where strength isn’t compromised. The underside of the pin bosses can be shallow spot-faced, or a radial cutter can be used to remove an equal amount of weight from both bosses.

Considering the high-quality and uniform precision manufacturing of today’s aftermarket performance pistons and pins, some builders opt to simply weigh the piston/pin and locks together as a package.

Ring packages from the same set weigh the same, so there’s no need to weigh the complete set of rings. Weigh the package for one piston (top ring, second ring, and oil ring package). If your oil ring package requires a support rail, don’t forget to include the support rail in the weighed package.

A sample bobweight card. This provides the technician with the necessary information to create the bobweights. This information should be kept on file in case this assembly requires service in the future.

During makeup of the bobweights, they’re weighed on the digital scale and adjusted (with more or fewer weights to match the required weight).

Once the bobweight card has been completed, the individual bobweights are assembled.

For other engine configurations, different percentages of the reciprocating weight may be required. The balancing-equipment manufacturer usually provides a reference chart, or has this information programmed into its computer software.

Once the total bobweight is determined, the weights are assembled to duplicate the real-life reciprocating mass.

Overbalancing

A 50-percent factor is normally used for most balancing jobs. But for certain racing applications with high compression ratios and/or high cylinder pressures, some builders prefer to slightly overbalance, using a factor of 51 percent. This adds a bit more weight to the crankshaft counterweights, which counteracts high-compression resistance. This theoretically reduces the negative torque created by the compression force, aiding in further compacting the air/fuel charge.

In certain instances, a high-revving race engine may experience a slight out-of-balance vibration at a specific RPM. In this situation, a slight overbalance may be beneficial by increasing the reciprocating weight factor to 51 percent or more. In doing so, the out-of-balance point may be moved to a lower engine speed range that isn’t critical to the race engine’s use. Overbalancing allows you to optimize crankshaft balance within the most important range of engine speed (the sweet spot) for the specific type of racing.

If you are balancing a four-cylinder in-line crankshaft, there is no need to create bobweights. Since the crankshaft has two opposing strokes, the dynamic forces tend to cancel each other. In order to balance this type of crankshaft, weight match all pistons and rods as you normally do for a V-type engine. Without bobweights attached to the crankshaft, spin and balance the crank.

Installing

The crankshaft is positioned on the spin balancer’s V-blocks at the crankshaft’s front and rear main journals. The V-blocks have nylon rubbing blocks to protect the main journal surface, which must be lightly oiled before positioning the crankshaft. The bobweights are installed to the crankshaft rod journals, with each journal’s weights set 90 degrees from each other.

The bobweights must also be centered along the width of the journal. Most spin balancers have a drive belt that contacts the center main journal. With the crankshaft fitted with its bobweights, the spin balancer is turned on to spin the crank. The balancing machine displays the existing heavy or light areas of the crankshaft relative to zero, and indicates where weight must be removed or added relative to the front-to-rear counterweghts as well as the radial point of the counterweights.

If weight must be removed, it is done by drilling to remove material from the counterweights. This can be accomplished with an overhead drill press, drilling into the outer edges of the counterweight, or, as determined by the balancing technician, by machining material from the outer faces of the counterweights on a precision lathe.

Bobweights should be centered at the width of each rod journal. To save measuring time, machinists often insert an aluminum spacer of a specific thickness to avoid the time required for measuring to center the bobweight.

Each bobweight is placed with the weight side 90 degrees to each rod journal.

Example of a bobweight centered on the journal width.

Example of a bobweight centered on the journal width.

Bobweight bases have V-cuts that rest against the rod journal. Each end of the bobweight is tightened evenly.

Depending on the type of balancing machine, information is provided on the display screen regarding the drilled-hole diameter and depth required.

If weight is to be added, the crankshaft counterweight is first drilled to a specific diameter and depth, then filled with a heavy-metal tungsten slug. If the slug is installed to the radial edge of the counterweight, the technician then welds the slug in place to prevent it from slinging out of the counterweight. Most balancing technicians prefer to drill and install a tungsten slug horizontally through the face of the counterweight, eliminating the potential for accidental slug departure due to centrifugal force.

Each time weight is removed or added, the crankshaft is spin checked again to verify the change in balance because performing a weight change at one end of the crank can affect the opposite end. In some cases, as many as six (or even more) balance corrections may be needed as the technician chases the balance.

Balancing Procedures

Before attempting a crankshaft balance, always inspect the crankshaft for runout. If it is bent (excessive runout), the balancing machine displays a substantial difference in weight between the front and rear counterweights. Always check for runout before wasting your time trying to correct balance.

Inspect the crankshaft stroke and verify that each stroke distance (the centerline of the rod journal to the centerline of the main journal) is identical. This is especially important if the crankshaft has been reground. Slight differences in stroke affect balance.

Balancing is the final step in crankshaft preparation (aside from a final polish of the journals), so be sure that all machining that could affect balance has already been performed. This includes crankshaft machining, piston machining, rod bearing selection, etc. It’s important to note that any change in the weight of the reciprocating parts changes the overall balance. If, during a rebuild, you need to replace even one piston, do not assume that the replacement piston weighs the same as the original, even if it is the same size, style, and brand. Whenever any part of the reciprocating assembly is changed, the crankshaft must be rebalanced.

When weight must be removed from a crank counterweight, it is done on an overhead drill press. Some balancing machines incorporate a drill while a separate drill press is required for other systems.

If it’s necessary to add weight to a counterweight, it can be done at the edge or at the face. If weight is added to the outer edge, it’s necessary to tackweld the weight in place to eliminate the possibility of it being slung outward. If weight is added to the face, a press-fit is adequate. Because of the required location of the weight shown here, the rear weight was drilled to access the target counterweight for drilling. A heavy-metal slug (tungsten, also known as Mallory metal) is press-fit into the target hole. Again, the technician refers to a chart specifying the diameter and length of tungsten required for a specific weight factor (in grams).

The monitor on this balancer’s screen displays all of the weight data input by the technician.

This Hines computer balancer provides a dynamic graph that shows the location required for weight removal or addition, in terms of clock position and depth at the counterweight.

A flywheel or clutch pressure plate for an internally balanced crankshaft should have a zero balance right out of the box. But if the goal is to follow a blueprinting approach, don’t make that assumption. Separately check the flywheel (or flexplate) and the clutch pressure plate and correct the balance if needed. Although an approximate flywheel and/or pressure plate state of balance may be adequate for routine street driving, blueprinting requires trying to eliminate all variables and deviations.

However, is not critical, and often not practical, to achieve a perfect-zero crankshaft balance on the balancing machine. Even the movement and migration of slinging and clinging oil can slightly alter dynamic balance. Balancing the crankshaft to within 2 to 4 grams is acceptable. Just because you might achieve a zero balance on the machine, it doesn’t mean that the crankshaft will experience zero balance during engine operation. Be realistic. You can spend hours in chasing a zero balance, often with no additional benefit.

Written by Mike Mavrigian and posted with permission of CarTech Books

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-balancing-guide/

The post How to Blueprint Engines: Balancing Guide appeared first on Muscle Car DIY.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-intake-manifolds-guide/

Manifold Types

Intake manifold design affects peak power and the RPM band where the engine produces maximum torque and power.

Following a hydrographics treatment, a high-performance clear-coat finish is placed on this intake. Even after a full day on an engine dyno and after spilling fuel during carb changes, the urethane clearcoat held up without a single blemish.

Single-Planes

A single-plane manifold (depending on overall height) can be produced with longer runners and the ability to improve alignment of the cylinder head’s intake port roofs. The larger plenum area with larger cross-sectional area provides a more direct shot at the cylinders, favoring the upper RPM band. The “straighter” runners tend to slow the mixture, which aids in reducing fuel separation (fuel droplets).

Single-plane manifolds are offered in a variety of runner lengths and overall heights. Generally, the longer the runners, the more suited the engine becomes for top-end power.

If the manifold has a divider plate, you can cut it down to increase plenum volume for better top-end performance. Rather than messing with the divided plate, try installing a carb spacer (experiment with thicknesses).

Single-plane intake manifolds are generally designed to allow optimum airflow at higher engine speeds. Single-plane manifolds have a larger plenum volume area, and the runners flow more directly at the cylinder head intake ports.

Dual-Planes

A dual-plane manifold has a split plenum with an upper plenum pocket directing the charge to four select cylinders. The lower plenum pocket directs the charge to the remaining four cylinders (delivering air/fuel to cylinders firing 180-degrees apart).

The runners are generally longer (better for low-end engine torque) and of a smaller cross-sectional area (which increases velocity).

A dual-plane intake manifold is usually the best choice for street driving because the design is targeted at idle, low-end torque, and low-end throttle response.

Some tunnel ram intake manifolds, such as this one from Pro-Filer, have a modular plenum top. This not only gives you a choice between using a single or dual carb setup, but the open access makes it very easy to inspect for port matching to the cylinder heads.

The plenum top attaches with a series of bolts and is sealed with a one-piece gasket.

A dual-plane manifold with a divider wall. Each half of the plenum directs the fuel/ air flow to half of the cylinders. Note the grid pattern in the cast floor of the plenum. This is intended to help bust up the mixture for better atomization.

Intake manufacturers have devoted years of development and are always searching for ways to improve airflow and to maximize engine performance at specific ranges of engine speed. One example is Edelbrock’s Performer RPM AirGap dual-plane manifold (developed from the Performer RPM). The runners are more isolated from engine heat and the height was increased for additional plenum volume. This improves the compromise between a dual-plane and singleplane, maintaining low-end performance of a dual-plane while increasing top-end power.

While the aftermarket offers dualplanes that focus on low-end idle quality, single-planes focus on the top end. Either design is slightly altered to broaden their ranges, and therefore multiple choices abound. I wish I had the space to devote to this subject in depth here, but suffice it to say that hood clearance issues aside, a dual-plane is likely the best choice for street cruising, and a single-plane is likely the best choice for high-RPM performance.

Tunnel Rams

A tunnel ram intake manifold is simply a larger, longer, taller version of a single-plane manifold. Although a tunnel ram system really isn’t a good choice for ordinary street driving, everybody thinks that a tunnel ram with dual carbs just looks cooler and they convince themselves that they can’t live without this setup.

A tunnel ram can be suitable with careful tuning and component selection. A pair of 650-cfm carbs is a usual choice, but the tunnel ram manifold needs to A dual-plane intake manifold is usually the best choice for street driving because the design is targeted at idle, low-end torque, and low-end throttle response.

Increased flow was needed on this 632-ci Dart big-block. The Pro-Filer tunnel ram and 1,150-cfm Holley Pro Dominator carb helped this bad boy pull 1,115 hp on the dyno (all engine with no nitrous boost).

A cross-ram intake manifold is another type of single-plane design, but with even longer runners than those on a tunnel ram.

Wet versus Dry Manifolds

One very basic difference between a carbureted intake manifold and a manifold used for fuel injection deals with the nature of flow. A carbureted intake manifold is referred to as a wet manifold because a mixture of air and fuel is fed through the manifold on its way to the cylinder head. A manifold for fuel injection is referred to as a dry manifold, since only air is flowed through the manifold (with injectors introducing fuel spray at the exit area of the manifold runners).

If the manifold is designed for a tall-deck aftermarket block, there may be a gap at the front and rear manifold rails. In this case, a manifold rail spacer kit is available to fill this gap.

Because of this basic difference, the surface finish and shape requirements of the intake manifold runners can differ. Although many variables come into play in the specific build, the surface finish may be more important in a wet manifold. This is because you’re dealing with flow, tumbling, and velocity of a wet (air and fuel) mixture (with the surface finish playing a role in how the fuel droplets can cling or atomize during flow). With an injected manifold, surface finish is likely less critical due to the absence of fuel handling.

Port Matching

Port matching refers to achieving a proper alignment and shape between the intake manifold intake ports and the cylinder head intake ports. Depending on the cylinder head and manifold selection, a slight mismatch can occur, resulting in an airflow interruption or turbulence as the charge leaves the manifold runner and enters the cylinder head port. Most commonly, the intake manifold port exit is then modified in order to match the exact location and shape of the head intake port. This usually involves grinding material from the manifold runner port.

The rail spacers are predrilled for use with locating pins. Each rail is machined to conform to the front and rear block rails.

Installing locating pins ensures that the spacer installs at the correct location, and that the spacer can’t accidentally move during assembly or during engine operation.

Verify that the installed rail spacer matches the block deck angle.

A neat way to seal is with RTV. Before applying RTV to block/manifold end rails, carefully mask off the block face and manifold rail face (or in this example, the rail spacer). Apply the RTV, allow a few minutes for partial setup, and install the manifold or spacer. The excess RTV can be wiped off without smearing the block or manifold. Once the excess is removed, carefully remove the masking tape. The result is a sealed joint that looks neat and tidy.

The first step in port matching is to carefully measure the cylinder head intake ports and the intake manifold ports. If the intake manifold ports are wider (for example) than the intake ports on the head, first grind to widen the head ports to match the same width. Then grind the intake manifold roof and floor areas to match the head. The goal is to have the same port size at manifold and head, and to have them align with no steps or interruptions. However, it’s common to size the intake manifold ports just a bit smaller (by about .015 inch or so) to accommodate any play or slop in the manifold bolt holes.

Before you start grinding, establish the fixed reference points; use the block that you intend to use with deck height finished. Install the heads with the exact type of head gaskets to be used during final assembly, or shim the heads to mimic the head gasket thickness. Also shim the space between the manifold and heads with the same thickness of the crushed intake gaskets (it’s best not to use actual intake gaskets because they may interfere with precise outline scribing).

Place the manifold onto the block and heads and tap it down to make sure it’s fully seated. Check to see if either the floor or roof of the ports aligns with the head ports. It’s best to establish roof alignment. You can change shims to raise or lower the manifold to achieve roof alignment (just remember to use intake gaskets of the same thickness during final assembly). Slide the manifold fore and aft to check for common-wall alignment (the thin walls that separate ports).

Apply machinist’s dye to the manifold deck around each port. Using calipers, measure the head ports (height and width). Using the previously established roof height as the index, use a precision straightedge and scribe a horizontal line across the entire manifold deck, in-line with the roofs. Using the height and width measurements taken from the cylinder head ports, use the straightedge and a scribe to mark the horizontal (floor) and vertical (wall) guides onto the manifold decks (you’re simply transferring the head port locations to the manifold).

Select a cutter bit with the same radius as the port corner radii (if in doubt, apply machinist’s dye to the head port corners and hand roll the cutter in the corner to see if the cutter makes full contact with the corner radius). Using a radius-nosed cutter bit on a controllable-speed electric die grinder (more controllable than pneumatic), begin to cut the ports edges exactly to the scribed outlines. Once each edge is cut open to the scribe line (and straight), blend the grinding into the port at a depth of about 1 inch (possibly shorter, depending on the manifold design). Do not grind beyond your scribe marks. Remember, for aluminum cutting, you must use a wide-flute bit designed for aluminum (otherwise you clog the flutes).

Once all ports have been cut, finish by smoothing and polishing with a 60-grit abrasive roll on the die-grinder tool. If you want a smoother finish, follow this with an 80-grit roll.

You can also take advantage of intake manifold gaskets in your attempt to port match. For instance, if the floor of the manifold ports are a bit lower than the floor of the head intake ports, you could move to a thicker intake gasket to slightly raise the manifold. For popular engines, manifold gaskets are available in a variety of thicknesses. Consider this before you start hacking away at the manifold or head.

If using different intake gasket thicknesses doesn’t solve the initial alignment (for manifold installed height), it may be necessary to remove material from the intake manifold mounting flanges to achieve good port alignment and sealing surfaces.

Port Matching and Machining

The following are some general rules for decking and milling blocks, heads, and intakes for port alignment:

If a cylinder head is angle milled, the intake face on the cylinder head must be adjusted at the same angle, with minimal material removed. It then may be necessary to increase the diameter or create slotted bolt holes in the intake manifold for attachment to the cylinder heads.

For 90-degree V-8 engine blocks, for each .010 inch removed from the head or block deck, the intake port opening is expanded by .007 inch. In order to bring the port alignment back into position, the intake manifold needs .005 inch of material removed from each side to effectively make the manifold seat lower on the heads.

In most instances you can just divide the total amount of decking on one bank in half to calculate intake manifold adjustment.

Port matching really isn’t necessary unless you’re trying to optimize engine performance or encounter serious misalignment for tolerance stack-up. If you’re simply toodling along on your way to a show or the local malt shop, don’t fret over this.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-intake-manifolds-guide/

Intake Plenum

For a carbureted manifold (or a carb-style manifold that uses a throttle body), take a look at the plenum divider walls. Remove any imperfections (casting bumps, flashings, etc.). In order to aid in airflow or fuel/air flow, address the dividers. The dividers typically (not always) have rough or almost squared off edges. Using a grinder or abrasive roll, radius these edges to a bull-nose shape (not to a sharp knife edge). The goal is to remove sharp edges and/or abrupt surfaces that could create excess boundary layers (turbulence).

Before you start checking port alignment, apply machinists’ dye to each port opening. This allows you to easily see any scribe lines.

After using the port roofs as the reference points, and after measuring the cylinder head ports, the dimensions are transferred to the intake manifold.

In some cases, where the manifold ports are smaller than the head’s ports, using a U-bent wire allows you to reach into the manifold, using the short vertical section to guide you around the head port, while scribing outlines around the manifold ports. Here Jim, of Fox Lake Racing Heads, prepares to scribe a lower intake manifold for a 5.0L injected Ford.

A machinists’ precision straightedge is used to scribe common floor lines across the entire bank of ports.

When cutting aluminum, be sure to use a cutter with large flutes designed for aluminum.

Proceed carefully. Make sure that you don’t remove any material beyond your scribe lines.

After removing material around the port edges to your scribe lines, taper blend the cut inside the runner at a depth of about 1 inch.

Blend into the port to fully smooth out the surface, again, at about a 1-inch depth. If you prefer a smoother surface (more of a polish), then go over the surfaces with 80-grit.

Depending on engine design/type, the manifold may have port pairs that are placed very close together. When port matching, align these divider walls to the heads first, and be careful not to eliminate the gasket sealing area.

The popular F.A.S.T. composite intake manifold for fuel-injected applications consists of a lower section (runners) and a top section that incorporates the throttle body inlet. Shown here is a unit for late-model Corvette.

Plastic intake manifolds for fuel-injection setups (OEM or aftermarket) are basically bolt-ons. Due to the weight-saving designs and preregistered elastomeric-seal grooves, you really can’t modify the ports.

Round off the edges of the port dividers to achieve a radiused profile. There’s no need to knife-edge these walls.

If you plan to use a carburetor spacer (to increase plenum volume for better top-end performance), apply machinist’s dye to the manifold’s carb mounting pad and install the spacer. If any manifold pad material extends beyond the inside walls of the spacer, scribe a line using the inside of the spacer as a template. Remove any exposed material from the carb pad to remove any obstructions to flow (match the manifold’s plenum opening to the spacer). Gently blend this area of the carb into the plenum opening.

Intake Port Surface

Although a fully polished surface that looks chrome plated may look really cool, this is usually not necessary. Finishing with an 80-grit abrasive roll is adequate polishing. Polishing is more important for any sharp turns in the flow path, which is where flow speeds are the highest. The shorter the turn, the more need for polishing.

Also, the need (or benefit from) polishing can vary depending in part on the size of the manifold runners. Smaller runners can benefit more from surface polishing than larger port runners. Smal-lvolume runners may be more sensitive to turbulence factors that can result from casting surface boundary layers.

Manifold Bolts

It’s common for a novice to undertighten, overtighten, or unevenly tighten intake manifold bolts. Any of these can result in vacuum, oil and/or coolant leaks, and a warped or cracked manifold.

Always follow the bolt torque specs and the specific tightening sequence recommended by the intake manifold manufacturer. A fairly common challenge, simply due to the design of the manifold, is gaining adequate access to certain manifold bolt locations. In some cases it may be difficult to access the bolt heads with a straight socket wrench.

It is common for installers to use an open-end wrench and to guess at torque value. In locations were you cannot access a bolt directly with a socket wrench, the answer is to obtain an offset wrench extension. This places the wrench (at the bolt head) away from the centerline of the tool’s drive head (making the effective overall length of the torque wrench tool longer or shorter).

When using an offset wrench, you must make a compensation adjustment in order to achieve the desired torque value. Otherwise, you unknowingly overtighten or undertighten the bolt. If the extension points out and away (but in-line with the torque wrench body) from the torque wrench drive, this obviously lengthens the overall tool length. If the extension is installed to the torque wrench 180-degrees (in-line with the torque wrench body but now underneath the tool), the effective length is shorter.

Use this formula so the adapter makes the wrench longer:

TW = (L ÷ L + E) x desired TE

Use this formula so the adapter makes the wrench shorter:

TW = (L ÷ L – E) x desired TE

Where:

TW = Torque setting on the torque wrench

L = Lever length of the torque wrench itself (from center of the wrench drive to the center of the torque wrench hand-grip area)

E = Effective length of extension, from the center of its square drive hole to the center of its wrench head

TE = Torque applied by the extension to the fastener

If you want to know where to set the torque wrench when using an adapter that alters the effective length of the wrench, you must calculate to compensate for the adapter. If the distance from the wrench drive to the center of the bolt makes the wrench longer, the final wrench setting must be adjusted to a lower value in order to compensate.

As an example, an intake manifold bolt torque value is listed as 30 ft-lbs. In order to access a hard-to-reach bolt, you may need to use a 2-inch offset extension wrench. In this case, the torque wrench measures 12 inches from the center of the drive to the center of the wrench handle. With the wrench extension pointing away from the wrench drive, this changes the distance from the center of the bolt to the center of the torque wrench grip to 14 inches (making the torque wrench 2 inches longer).

For this example, the formula works out like this:

TW = (L ÷ L + E) x desired TE

12 ÷ (12 + 2) x 30

12 ÷ 14 x 30

.9 x 30

27

In this example, the wrench is set at 27 ft-lbs, in order to actually achieve 30 ft-lbs.

If the wrench extension is aimed toward the handle (turned 180-degrees from the prior example), and you still want to achieve 30 ft-lbs of torque, you know that the adapter has now made the wrench shorter (because the center of the bolt is now closer to the center of the wrench handle).

Example of a dual-plane manifold for the Ford FE engine. Note the pushrod holes.

Wrench extensions are readily available from quality tool sources. Just remember to adjust the torque wrench accordingly to compensate for the added leverage.

The vintage Ford FE big-block manifolds have pushrod holes. For high-performance applications where larger diameter pushrods and/or high-lift cams are used, these holes may require slight enlargement or elongation. This must be checked during test fitting, with an assembled short block, heads, and rockers installed.

For those situations where you simply don’t have access with a socket wrench, a wrench extension makes it easy to apply the desired torque value to an intake manifold bolt, rather than just guessing at bolt tightness.

The MSD 6LS ignition module and harness makes converting an LS engine to carburetor extremely easy. There are two versions: the 6LS (PN 6010), designed for use with the 24-tooth crankshaft reluctor wheel (earlier LS1/LS6) and the 6LS-2 (PN 6012) for the later 58-tooth reluctor wheel (LS2 and others). Just make sure that you purchase the correct controller based on your reluctor wheel tooth count.

Converting a GM LS engine to old-school carburetion is embarrassingly simple, requiring only a manifold, carb, and an MSD ignition controller. No ECM required.

For this example, the formula works out like this:

TW = (L ÷ L + E) x desired TE

12 ÷ (12 – 2) x 30

12 ÷ 10 x 30

1.2 x 30

36

In this example, the wrench is set at 36 ft-lbs, in order to actually achieve 30 ft-lbs.

If the adapter makes the torque wrench longer, you must reduce the setting on the torque wrench. If the adapter makes the torque wrench shorter, you must increase the setting on the torque wrench.

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-intake-manifolds-guide/

Converting LS to Carb

The Gen-3 and -4 GM LS engine was originally designed to feature electronic multi-port fuel injection. For those who prefer to run a carburetor, for street rod, custom car, or racing, the swap is relatively easy. The only components required include a carburetor, intake manifold, and ignition controller system. No on-board computer is needed. You retain the engine’s ignition coils, crankshaft position sensor, camshaft position sensor, water temperature sensor, and manifold absolute pressure (MAP) sensor.

Because the carb and manifold handles fuel/air delivery, no electronics are involved. You simply need a way to time ignition. The commonly used controller for this application (and the only one I’m aware of) is the MSD 6LS controller, which includes a selection of six plug-in chips, each with its own ignition curve. Refer to the MSD instructions, pick the curve you want to try, plug it in, and go play. It’s that simple. If you prefer to map your own curve, a CD is included that lets you program the curve on your PC.

Be aware that you need to buy the correct controller for the tooth count on your crank’s reluctor wheel. The MSD 6LS (PN 6010) is compatible with a 24-tooth wheel (LS1/LS6 and early LS2), and the 6LS-2 (PN 6012) is for the later 58-tooth wheel (later LS2, LS7, LS3, and LS9).

Manifold Surface Protections

Okay, so you purchased a hot-dog aluminum intake that’s gonna boost the pony count, and it looks way cool squatting between those trick aluminum heads. However, a few months down the road, the manifold starts looking funky. It’s either scuzzing up with a white-hued film that rubs off like chalk or it starts looking brownish, as though it were rusting. How can this be? After all, it’s aluminum.

If the manifold begins to turn brown (as though a light surface rust were occurring), you’re not imagining this. If the aluminum manifold was steel-shot blasted during the manufacturing process, particles of steel may have been imbedded in the aluminum surface. Exposed to the elements, the steel begins to oxidize (if clean stainless steel shot is used, this does not happen).

If the aluminum surface begins to oxidize on its own (a result of moisture due to humidity or being exposed to water in some other manner), a white film begins to develop. Left unattended, this can lead to long-term pitting.

Penetrating Lube

In order to keep the new manifold looking, well … new, you have a few pre-installation options for treating the surface to prevent oxidation.

The cheap (and somewhat effective) route is to carefully wipe the exterior surface with a soft steel wool pad (or red Scotchbrite pad) that has been soaked with a penetrating lubricant such as WD-40. Using a bit of effort, rub the lube into the entire outer surface, including every nook and cranny. This changes the appearance, providing a slight burnished look and ever-so-slightly darkening the aluminum, yet providing a still-attractive appearance.

Once you’ve applied the penetrating lube into the surface with the aid of a light abrasive pad, rinse the manifold thoroughly with hot water to remove all abrasive particles. Dry the surface and immediately re-apply the thin penetrating oil using a soft clean rag. This generally keeps the intake looking spiffy for a season or two, and helps to prevent future staining. Down the road, you can always clean the installed manifold surfaces and re-apply the lubricant with a clean rag. When the light oil is applied, don’t leave it wet; dry and buff with a soft, clean rag (otherwise, the oil attracts dust/dirt particles). This may seem to be an archaic method, but it works as long as you maintain it via routine wipe-downs (detail cleaning).

Cleaning a bare (as-cast) intake manifold can be tricky if stained by fuel or road and weather elements because of the porous nature of an as cast surface. Commercially available aluminum cleaners include OxiSolv and Evapo-Rust. It’s important to follow the instructions included with these cleaning products.

Tumble Treatment

Another option is to have the manifold tumble-treated (where the manifold is gently tumbled in an immersion of small polishing stones). Depending on the size, shape, and composition of the media, this burnishing process smooths the surface to a satin, semi-polished, or full-polished finish, depending on what result you want. Although this doesn’t provide a protective coating, it diminishes or eliminates casting surface texture, which makes it much easier to clean. Of course, this can always be followed up by the application of a protective film or coating.

Coatings

You can also have the manifold professionally treated or coated with a protective finish. This can be done by adding a Teflon coating (the surface darkens but prevents moisture and other deposits from sticking to the surface), a ceramic coating (which generally brightens the surface, depending on the formulation), or a powder coating.

A good powder-coating shop can provide virtually any finish you want, including clear, a color , a smooth finish, a wrinkly finish, pebble finish, etc. There are plenty of good powder coating shops around.

A race manifold (usually) shouldn’t have a barrier coating (for heat dispersion), but for a street/show rod, appearance is paramount, so do what you need to do in order to maintain the beauty factor. Discoloration, stains, or oxidation can occur from weather conditions (humidity, airborne pollutants), fuel leaks, coolant leaks, etc. The proper protective coating eliminates surface oxidation and allows easy cleaning of other surface contaminants.

If a performance coating is desired, check with the major engine-component coating services. They offer a wide range of specialty coatings designed for whatever goal you have in mind, including anti-friction, heat barrier, heat dispersion, faster oil drainback, etc. These sources include (but are not limited to) Swain Tech Coatings, Polydyne, Calico Coatings, and TechLine Coatings.

Concerning intake manifolds specifically, underside coatings (where the bottom of the manifold faces the lifter valley) are available that provide a heat barrier (keeping the manifold cooler) and coatings that prevent oil from clinging (for quicker oil drainback).

Some intake manifold manufacturers offer their manifolds already treated with some type of protective coating as standard or as an option. If yours is delivered bare, seriously consider applying some type of surface protection simply to maintain a like-new appearance.

Hydrographics (wet ink film graphics) provides a simple and relatively inexpensive way to create a unique visual impact. This manifold was ground smooth, polished, then delivered to a dipping service. The techs at Dip ’N Designs (Wooster, Ohio) applied a black basecoat, carefully dipped the manifold through a water surface suspended with carbon-fiber ink film, rinsed, dried, and then clear coated the manifold. Since the graphic ink film is somewhat translucent, the black base coat was needed to achieve the desired hue.

Overhead view of the ”carbon fiber” manifold on a Pontiac 455 that we bored/stroked to 501 ci.

Topped off with a dual-snorkel vintage-style air cleaner, the intake/carb swap from its previous fuel injected format resulted in taking advantage of current day LS long-block technology while retaining a vintage performance look.

Using the Edelbrock dual-plane intake and a 650-cfm Holley (and a mild-cam change), we simply overbored this 5.3-liter LS iron-block to 327 ci and hit 450 hp. The manifold provided snappy throttle response and favored bottom-end and mid-range power.

Topped off with a dual-snorkel vintage-style air cleaner, the intake/carb swap from its previous fuel injected format resulted in taking advantage of current day LS long-block technology while retaining a vintage performance look.

Actual chrome plating, while attractive, probably isn’t a wise choice, simply because the plating process (copper, nickel, chromium) can trap heat within the manifold, more so than other treatments. If you want a chrome-like finish, a good powdercoater can achieve this for you. The coating shop may also be able to apply a chrome-type finish in other colors than nickel-chrome.

Hydrographics

This is also called wet-dip. It involves a preprinted ink film (graphics of your choice, such as carbon fiber, camouflage, etc.). The film is laid onto the surface of water in a temperature-controlled tank. The component (in this case a manifold) is carefully lowered onto and through the ink film, much like dipping an Easter egg. The film adheres to the manifold surfaces, wrapping all contours. The manifold is then removed, rinsed, dried, and treated to a protective urethane clearcoat. For best results, the manifold’s exterior surfaces need to be fully smoothed and polished prior to dipping.

Faux Fiber

I recently had a 4-barrel manifold (for a 501-ci Pontiac engine build) treated to a carbon-fiber graphic. I spent a few hours deburring the intake (removing casting flashings, casting-mold lines, etc.) and fully polishing the entire outer surface. I delivered the manifold to Dip ’N Designs. Because I wanted a black carbon-fiber appearance, they first applied a black basecoat (the film is somewhat translucent, so the undercoat influences the final hue), followed by dipping, rinsing, drying, and clearcoating. The result was spectacular. At a major performance trade show, everyone who inspected the Pontiac engine thought that the intake manifold was actually made of carbon fiber.

This graphic treatment does hold up to engine heat and contact with fuel. We ran this engine on a dyno for a full day, with no visible effects from the heat (no discoloration, no cracking, no lifting). Even with fuel spilled onto the surface during carb changes, the urethane clearcoat seemed impervious.

The only tip that I’d like to pass along deals with the intake manifold bolt-hole locations. The clamping force of the intake manifold bolt heads and washers tend to compress and raise the clearcoat around the edges of the washers. To avoid this, lightly spotface each bolt hole (flat-spot-face each bolt hole to slightly exceed the outer diameter of the washer). The spot-face doesn’t need to be very deep, just enough to register the washer. The spotface should be a few thousandths of an inch larger in diameter than the washer (for example, if the washer OD is .450 inch, the spotfacing should be about .470 inch). After ink-dipping and drying, the graphics technician can then carefully mask each spotfaced recess before applying the clearcoat.

Carb Spacers

Although some builders take advantage of a carb spacer simply to provide needed clearance between the carb’s fuel log and intake manifold (in cases where fit poses a problem), spacers are normally used to help tune the engine’s performance band. Spacers don’t add power; rather, a spacer can be used to tune the power band in the RPM range can only use generalities about each style of spacer, since each specific engine application has its own set of variables (a setup that works well on one engine might not act the same on a different engine).

Designs

Spacers are available in different designs, including four-hole, single-hole, open, combination, and with a plenum divider. There’s more to choosing a spacer than simply basing the selection decision on thickness.

A four-hole spacer (four holes that align with the carburetor barrels) generally increases throttle response and acceleration, and generally increases torque by moving the power band to a lower RPM range. The four-hole design forces the column of air moving from the carb into the intake plenum to take a longer path (flowing longer), which increases air velocity.

A spacer with a single, large, opening tends to raise the power band to a higher RPM range (less bottom end but more top end). This type of spacer also has a center divider plate that splits the plenum path left-to-right. For applications where rich/lean conditions exist on the engine’s left and right sides during turns, the divider plate helps to equalize fuel/air distribution for a more even feed to all cylinders. This is generally not required for street application, and is more targeted to oval track or some road-race applications. More advanced spacers are also available with tapered holes, where the taper angle has been developed for optimum performance on specific manifold/carb/cam setups.

An open spacer increases plenum volume by increasing the distance between the carb and plenum floor. The open type generally decreases throttle response.

A combination spacer has a fourhole design along with a relieved floor area (basically, a combination of a fourhole and an open style). The combination spacer design generally helps to increase throttle response, while also widening the torque and power band throughout the RPM range (sort of the best of both worlds). The top of the spacer (mated to the carb) has the four holes flush to the carb, while the underside of the spacer is relieved in a square pattern (encompassing the entire group of the four holes) to slightly increase plenum volume.

Materials

Spacers are offered in a variety of materials, including wood, plastic, phenolic, and aluminum. Stay away from wood and plastic (wood is a good heat insulator but can absorb fuel, and plastic isn’t very strong and can crack).

Phenolic fiber is a good heat insulator and is a good choice. But if you plan to modify the spacer (custom porting), phenolic isn’t very workable.

Aluminum (cast or billet) isn’t the best heat insulator, but it’s easily modified and, in the case of today’s precision-machined billet and color-anodized choices, is a great choice, especially for a custom application where appearance is key (a sexy red or blue anodized spacer can add some real pizzazz).

Thickness

Aside from providing mounting clearance, spacer thickness is a tuning variable. The thicker the spacer, the more you increase plenum volume.

For the typical owner who doesn’t have access to a dyno or flow bench, determining the optimum spacer thickness for a specific application involves some trial and error. Luckily, swapping spacers is easy. Remember, the shorter the spacer, the more low-end torque and power available. The thicker the spacer, the torque and power band moves to a higher RPM range.

If you do plan to play with spacer thicknesses, start with carburetor mounting studs that accommodate the thickest spacer that you have in mind. This eliminates the need to install specific-length studs during each spacer swap.

Written by Mike Mavrigian and posted with permission of CarTech Books

This tech tip is from the full book, MODERN ENGINE BLUEPRINTING TECHNIQUES: A PRACTICAL GUIDE TO PRECISION ENGINE BUILDING.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-blueprint-engines-intake-manifolds-guide/

The post How to Blueprint Engines: Intake Manifolds Guide appeared first on Muscle Car DIY.