Many of the formulas in this book require precision measurements to ensure accuracy. This chapter familiarizes you with the tools required to gather these measurements and some strategies for organizing and storing them for future reference. Most of the tools presented here are relatively inexpensive and can be added to your engine building inventory one or two at a time. Many of the hard-measurement tools shown are sourced from summitracing.com and are indicated where applicable. Others come from a variety of manufacturers who build specialized tools for unique tasks. The important thing is that all of these tools are very easy to use and they deliver the precision results necessary for competent engine blueprinting and assembly.
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Accordingly, it is important that you maintain good records of your measurements. A sample engine assembly sheet is included on page 145 for you to copy. It contains entry spaces for all the critical measurements you will normally require.
Over the course of your engine building experience you also may determine that there are other bits of data that you wish to keep track of for future reference. In much the same ways as explained in Chapter 13, you can create your own blank build (assembly) sheets for recording various measurements and arrange them any way you wish. The sample shown on page 145 could be made by creating a table in Microsoft Word or in Excel. You can easily rebuild this one in your own computer and modify or rearrange it to suit your personal needs. Note the secondary content sheet (page 144) that allows you to keep track of your engine’s contents including parts, part numbers, sources, and contacts.
You can ultimately build other sheets to store your engine balance data, cam cards, cam setup information, or anything else you deem important. The spreadsheet is the easiest way to do this, and in some cases you might even include a formula that automatically calculates something from measurements that you have entered on that page. You can make your entries directly in the PC or print out blank sheets to be filled out as required. Use the sample page as a reference or build your own. Measurements are a core component of any good engine build. You can never go wrong if you have accurate records. And if you are brainstorming engine combos on simulation software, you can open a second window and enter parts and specs into your engine build content sheet at the same time.
Measurement Tools, Standards and Accuracy
The most important characteristics of all measurement tools are accuracy and consistency. Modern measurement tools are exceptionally accurate and, when properly cared for, they are remarkably consistent. Most instruments that measure in thousandths of an inch will agree with each other on any given day as long as the temperature of the instrument and the component being measured are close to similar. Repeatability is a vital component of any measuring device and part of that responsibility falls on the measurement technician. The device must be used the same way every time and the component temperatures must be equivalent.
Suppose you live on the East Coast and the temperature outside is 10 degrees F on a crisp January morning. You can’t bring in a crank that has just made the trip to your location in the back of an open pickup truck and expect the measurements you take to provide an accurate readout of bearing clearances in a bare block with bearings that have been sitting in your heated assembly room all night. When you start measuring in tenths of a thousandth of an inch, temperature becomes a critical element, hence the use of checking standards to ensure accuracy. If you ask a machine shop to fit a set of pistons to a block with 0.0035-inch piston-to-wall clearance they will almost always hit it right on the nose. But if you get it back to your shop or home garage and your checking equipment indicates that the pistons are fitted at 0.004 to 0.0045 inch and a couple are even nudging 0.005 inch, whose measurement is correct?
Why is this so critical? Well, it’s because engine components are specifically designed to work together with clearances that account for variations in engine operating temperature, lubrication viscosity, engine speed, loading, and severity of operation. Lubrication clearances or tolerances are the facilitators that allow complex pieces of machinery like automotive engines to run smoothly and provide long-term durable service. Some of the instruments you may use measure other important things such as pressure, volume, weight, movement, and so on. These instruments are also influenced by temperature and the way you use and care for them.
All of the measurement tools presented below are designed to provide accurate measurements that will adhere to common standards. As long as you keep them clean and take proper care of them, they will deliver consistently accurate measurements that you can accept with confidence.
16-inch Pro Degree Wheel
Larger-diameter degree wheels are popular with most professional engine builders because they afford greater precision and ease of use. They are sturdy enough to use for rotating the engine during cam setup when only the crank, camshaft, and one piston are installed. These wheels offer full 360-degree bright markings in 1-degree increments and are made from anodized aluminum for durability.
32-inch Precision Metal Straightedge
An inexpensive metal straightedge is used to check for straightness and alignment on engine blocks and cylinder heads. With accuracy to within 0.001 inch, it is used in conjunction with feeler gauges to check for straightness or high and low spots. It is particularly useful for checking the straightness of cylinder block and head deck surfaces and the alignment of main bearing housing bores.
Burette and Stand Kit
Used for cc’ing intake ports, combustion chambers and other volumes. It comes with a clear molded glass burette with a Teflon petcock. The burette is graduated in 0.20-cc increments and sharp easy-to-read lines that are numbered every 2 cc’s. A kit includes an adjustable metal stand for easy positioning with any size cylinder head or any other checking requirement.
Cam Checking Tool
A cam checking tool slips into the lifter bore with a cam follower and dial indicator for accurate measurement of lobe lift and base circle run out. It can be used in conjunction with a degree wheel for cam checking and degreeing. It comes with two followers: one for flat tappets and one for roller lifters. The double-ended design allows it to fit both GM (0.842-inch) or Ford (0.875-inch) lifter bores. It comes complete with dial indicator, locking set screws, and rubber O-rings to hold it stable in the lifter bore.
Degree Wheel Kit
A cam checking and degree kit that can be used with the heads on or off the engine. Includes a cam lobe checking fixture with a 1-inch dial indicator and a 5-inch extension, TDC locators, and an 11-inch precision degree wheel. It can be used on blocks with 7/16- or 1/2-inch head bolt holes or on cylinder heads with 1/4- or 5/16- inch valve-cover bolt holes. The degree wheel is separately highlighted for intake and exhaust events, intake centerline, and exhaust centerline in 1 degree increments.
A depth mic is handy for quick measurements of deck height, piston rock, valve depth in combustion chamber, and other measurements that require a depth probe. Most tools have a range of zero to 1/2 inch or zero to 1 inch in 0.001-inch increments, just like a micrometer.
Dial Bore Gauge
A dial bore gauge is the only accurate way to measure cylinder bores, main bearings, rod bearings, and other inside diameters. They take precise measurements to within 0.0005 inch and are used for checking cylinder bore straightness and taper and for determining piston to wall clearance. Most units come with a full range of addon anvils for measuring bore diameter from 2 to 6 inches and up to 6 inches deep.
Perhaps the engine builder’s second most handy tool. The digital stainless steel caliper has a large LCD display window with direct readout in metric or SAE units. It measures from 0 to 6 inches in 0.001-inch increments. Most units come with a battery included and a protective storage case. Can be used to measure piston skirts, journal diameters, and assorted depths and heights with the inside or outside jaws.
This is the engine builder’s basic measuring tool. Used in conjunction with a magnetic base, bridge stand, or other holding devices, dial indicators are used for checking crankshaft thrust, camshaft end play, deck height, valve travel, and many other measurements from zero to 1 inch in 0.001-inch increments. They have a rotational clamp for zeroing the indicator at any point, interchangeable contact points, and continuous dial gradation in 0.100 inch per dial rotation with a smaller dial indicating the number of total dial rotations up to 10. Special extended-travel versions are available for checking stroke length and other longer measurements.
Dial Indicator Bridge Stand
A bridge stand positions a dial indicator directly over a deck surface or cylinder bore for the purpose of checking deck height, valve pocket depth, piston rock, piston-to-head clearance, deck flatness and runout, and other comparative measurements of one flat surface to another. Accepts most standard dial indicators.
Dial Indicator Magnetic Base
A magnetic dial indicator base allows you to position a dial indicator in almost any position necessary to obtain a precision measurement. They accept all standard dial indicators and feature a heavy-duty magnetic base for easy attachment to cylinder blocks and iron heads. The base features a powerful magnet with on/off release lever and integral clamps for horizontal or vertical adjustments. Some base styles have a semi-rigid articulating arm that can be twisted to almost any position. The dial indicator itself is not included in most magnetic base kits.
Digital Compression Gauge
A digital compression gauge reads engine cranking pressure in individual cylinders up to 300 psi. A good one comes with common spark plug hole adapters and includes automatic shutoff once it has recorded an average pressure. It features zeroing with a convenient push-button relief valve. A sound engine will have compression readings within 10 percent of each cylinder, but the actual amount of compression varies according to contributing factors such as cam timing and static compression ratio. Compression testers are primarily used to assess the condition of valves and piston rings in each cylinder.
Digital Torque Adapter
PowerBuilt Tools by Alltrade makes a great digital torque-wrench-calibration tool that calibrates any torque wrench and doubles as an actual torque wrench when attached to a standard ratchet or breaker bar. It also provides visual and audio indicators when reaching specified torque and records the last 50 torque-value readings. It calibrates from 29.5 to 147. 6 ft-lbs.
Digital Valvespring Tester
A digital or manual valvespring tester is used to check spring pressures at the manufacturer’s recommended installed height. By checking tension at different heights, the spring rate can be calculated and compared to the manufacturer’s published specs. Most units feature a positive stop at an adjustable desired height. Digital units are convenient because you don’t have to read small gradations on a dial.
Feeler gauges are typically used for measuring connecting rod side clearance, ring groove clearance and end gap, valve lash, and other measurements that require a flat blade of calibrated thickness. They are available at any hardware store and most come in a range from 0.002 to 0.035 inch. Those intended for valve lash work often have angled tips for easier insertion between the valve stem and rocker arm tip and they come with fewer sizes that accommodate the most commonly used valve lash settings.
Light Checking Springs
Light tension springs are used to hold the valves in place for flow bench work and other tasks such as measuring valve lift and valve-to-piston clearance, degreeing a cam, or checking rocker arm ratios. They also hold the valves closed with sufficient tension for cc’ing combustion chambers and ports or while adjusting valve open position on a flow bench.
Mr. Gasket’s Hot Rod Calc
Another great tool from Summit Racing is the hand-held Hot Rod Calc; a convenient hand calculator containing all the formulas in this book and more, including vehicle dynamics calculations, weather and performance predictions. It is probably one of the first things you should buy when you start building your own performanceengine tool kit.
Outside Diameter Micrometer Set
A set usually consists of three separate micrometers capable of measuring from zero to 1 inch, 1 to 2 inches, and 2 to 3 inches. Most have a positive locking clamp and a sensitive ratchet stop to prevent overtightening. Micrometer sets come in a wooden case and include calibration blocks so you can zero them correctly. They are primarily used for measuring bearing journals, wrist pins, and other rounded surfaces. If you intend to check piston skirts, you will have to purchase separate larger micrometers in the 3- to 4-inch and 4- to 5-inch ranges.
PerformAIRE Air Quality Computer
This handheld digital unit measures density altitude to within 50 feet. Essential for calculating jet changes or calculating fuel pressure changes on EFI systems. It also monitors temperature, barometric pressure, relative humidity, and other values that are displayed on an easyto- read LCD screen.
Pushrod Length Checkers
COMP Cams makes the best pushrod length checkers because they have graduated vernier caliper-like scales marked directly on the adjustable pushrod. Each full turn advances the length of the pushrod by 0.050 inch so all you have to do is count the number of turns from the fully closed positions. Use them to establish proper rocker arm geometry before ordering exact-length pushrods.
Rod Bolt Stretch Checker
A dedicated tool for accurately measuring rod bolt stretch with a dial indicator. Compares the length of unstretched bolts to the length after torquing. Allows the bolt to be further tightened to manufacturer’s recommended stretch rather than a specific torque.
Snap gauges are handy adjustable gauges for measuring the inside width or diameter of various ports or openings. They have a compressed spring that provides tension to expand against the sides of the object being measured. A locking device freezes the measurement, which is then read using an outside mic. They are available in a common range of sizes or in a kit. You won’t use them a lot, but they are handy when necessary. They are inexpensive and available at most local tool outlets.
Stroke Length Checker
A precision stroke length checker consists of a pair of equal-length aluminum bridge stands with V-cuts on the bottom to center the device on adjacent main bearing journals. The gap between them is bridged by a bar with a dial indicator and extension that reads the stroke as the crank is rotated in a set of V-blocks. It requires a special dial indicator with a capability of reading up to 41⁄2 inches of travel.
Summit Cam Checking Fixture
Summit’s heads-off cam checking fixture positions the dial indicator and 5-inch extension in the correct position over the lifters so you can obtain accurate readings without the need for a magnetic dial indicator base.
TDC Indicator Stop
A universal deck mounted bar with an adjustable positive top for finding TDC in conjunction with a degree wheel. Mounts to the block deck surface using existing head bolt holes.
Valvespring Height Micrometer
These come in two sizes and allow you to directly measure valvespring installed height with the correct retainer. They measure within 0.005 inch and have a height range from 1.400 to 1.800 inches or 1.800 to 2.200 inches. A later version is also available for checking the newer beehive-style springs. They are the most accurate way of checking installed spring height.
Written by John Baechtel and Posted with Permission of CarTechBooks