The 1950s saw the introduction of the Holley Series 4150 4-barrel on the 1957 Thunderbird. It was the beginning of the modular Holley 4-barrel, as we know it today. It was the first true performance carburetor and it became standard equipment on many high-performance automobiles.
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The 1960s were huge for the hot rod industry and Holley; the 4150 became original equipment on many iconic Detroit factory muscle cars, powering such notable beasts as the popular Z28 Camaros, big-block Chevelles, Boss Mustangs, and Shelby Cobras. This era also saw the introduction of the Holley three-deuce multi-carb setups on 427 (Tri Power) Corvettes and 440 (Six Pack) Mopars. The now-famous Holley Double Pumper was also born in the 1960s. According to Holley, the now-world-renowned Dominator, which is a Double Pumper, was developed specifically for NASCAR racing and made its debut in 1969.
The 1970s saw Holley’s continued dominance in racing with nearly every factory NHRA Super Stock/Pro Stock racer running Holleys. That hasn’t changed; Holley carbs have powered more drag racers than all other carbs combined. This era also witnessed the introduction of Holley aluminum intake manifolds, including the once-popular Z-Series developed in conjunction with Zora Arkus-Duntov.
The 1980s marked Holley’s entrance into the fuel-injection market for which original-equipment EFI components and analog Pro-Jection retrofit fuel-injection systems for carbureted cars were introduced.
In the 1990s Holley continued its new product introductions. The wildly popular HP Pro series of race-ready carburetors was introduced and has become the standard in racing. SysteMAX engine kits were introduced with matched cylinder heads, intakes, and cams. Also in the 1990s, the Dominator evolved into the HP Dominator, huge billet electric fuel pumps were introduced, and retrofit EFI kits evolved into digital Pro-Jection 4D and 4Di.
Beginning in the 2000s, Holley introduced the popular Street Avenger, Truck Avenger, Street HP, and Ultra HP carburetors as well as billet mechanical fuel pumps and high-flow billet electric pumps. Although not covered in this book, Holley’s EFI systems have seen an enormous amount of change with the introduction of Avenger EFI, HP EFI, and Dominator EFI.
Holley ID System
Two basic numbers are attributed to each Holley carburetor: the model/ series number and the list/part number. The series number indicates the general type, or series; for instance, 4150, 4160, or 4500.
The 4150 series is the original 4-barrel modular design, which features metering blocks and replaceable jets on both the primary and secondary sides. The 4150 series is available with either mechanical or vacuum secondary operation.
The 4160 series is a slightly less-expensive variant of the 4150, featuring replaceable primary jets, but with a thin metering plate on the secondary side and no replaceable secondary jets.
The 4500 series is the Dominator big-CFM racing series, with a larger main body and a unique secondary actuation linkage design.
The model number is not stamped on the carburetor, but it’s easy to identify by simply examining the carburetor. If the secondary side has a metering block with jets, it’s a 4150; if not, it’s a 4160. The Dominator is easily identifiable by its size and the shape of the throttle bores.
For all practical purposes, the “list” number is the part number of the carburetor; it is the top number stamped on the carb. The list number is also stamped on the choke housing/air horn of all Holley carburetors that have a choke housing. Keep in mind that the Dominator series and some other race carbs, such as the Ultra HP series, do not have a choke housing; their list number is stamped on the top of the main body.
The list number may be preceded by either the word “LIST” or by the letter “L.” The factory used the word “LIST” or the letter “L” randomly. Don’t worry about it. Some carbs have it and some don’t.
For example, a LIST 3310 is a 4150 series with either a 750- or 780-cfm rating, depending on when it was made. Another example is a Street Avenger carb’s choke housing/air horn stamped with the part number (e.g. 80670), without “LIST” or “L.”
A dash followed by a single- or double-digit number may be found immediately following the part number. This dash number simply indicates that a running change for that particular part number of carb had occurred (perhaps a die was changed, or other evolutionary production change). A –1 indicates the first running change. A –4 indicates the fourth running change, etc. From a selection/purchasing standpoint, you don’t need to be concerned with this number.
Located underneath the part number is a four-digit number, which indicates the build date. For instance, a build date might be 1954. This indicates that this particular carb was built on the 195th day of a year ending in “4” (which could mean 1974, 1984, 1994, or 2004).
Although this may seem confusing, dating a Holley carburetor is generally not too difficult. A date code should appear below the list number. Older carburetors have a three-digit code, while carbs made after 1972 used a four-digit code. You can always call Holley’s tech hotline and ask a Holley technician to help decipher the date code, but remember, this number doesn’t have any particular use for you, so you really don’t need to worry about it.
Series 4150 and 4160
Holley 4150s and 4160s are built on similar platforms with a few distinct differences. They both have square bores; the primary and secondary throttle bores are the same size, in a “square” configuration, in contrast to a spread-bore that has smaller primary and larger secondary bores. The 4150 is a square-bore carb with center-hung floats and dual fuel feed inlets, and replaceable jets in both primary and secondary metering blocks. The 4150 carbs with vacuum-operated secondaries have an accelerator pump and a power valve on the primary bowl, but no accelerator pump or power valve on the secondary bowl. The 4150 carbs with mechanical secondaries are known as Double Pumper carbs; they have the addition of a secondary accelerator pump, and depending on the specific part number, may also have a power valve on the secondary side.
The Series 4160 carbs also have a square-bore pattern but with more basic features. The primary side has a metering block with jets, but the secondary side has a thin metering plate with pre-sized orifices. Although a metering block has replaceable jets for tuning purposes, a metering plate (used in the secondary side of 4160 carbs) requires changing the metering plate for secondary “jet” size tuning. Metering plates are available in a range of main-hole and idle-hole configurations. Secondary metering plates are secured to the main body with six 8-32 clutch-head screws, so you should obtain a 5/32-inch clutch-head driver for proper servicing during removal and installation.
A 4160 can be converted to a 4150 by adding a secondary metering block in place of the metering plate and swapping to center–hung-float fuel bowls. A 4150 can be converted to a 4160, although it is not a popular modification.
If a 4150 carb has mechanical secondary operation, it has both a primary and secondary accelerator pump, and is referred to as a Double Pumper carb. Depending on the model, 4-barrel carburetors have either vacuum-operated secondaries or mechanical secondaries.
All primary sides include an accelerator pump, which is activated by the throttle linkage. The pump serves to inject an added boost of fuel to eliminate bog or lag when the throttles are opened, which is especially critical at lower engine speeds.
With a vacuum secondary design, the secondaries begin to open according to vacuum developed in one of the primary bore venturis, as engine load increases. During quick accelerator operation under load, a slight delay may be encountered while the secondaries begin to open. You can tune the vacuum secondary by changing to a lighter or heavier spring inside the vacuum diaphragm housing.
Double Pumper carburetors are equipped with mechanical secondaries; a second, separate accelerator pump circuit is located on the secondary side. The secondaries receive an immediate shot of initial fuel from the secondary’s accelerator pump as the throttle linkage progresses.
Double Pumper carbs are best suited to lighter-weight vehicles, those equipped with a manual transmission, and those with high– stall-speed automatic transmissions in the 3,000-rpm range.
Introduced In 2009, the HP-series Street Avenger includes cast aluminum bodies with billet metering blocks and baseplates that reduce overall weight by an astounding 5 pounds compared to previous 4150 carbs. This line of carbs is also offered in both diecast and aluminum body construction. The Ultra Avenger series offers some appearance enhancements such as metering blocks and bodies in Hard Core Black, Hard Core Gray, blue, and red. The lineup is quite extensive.
In 2011, Holley released a new aluminum Ultra HP 4150-series carb with 30 new and improved features, including larger 1.6-inch venturis. The Avenger series is offered in ratings from 470 to 870 cfm, in both street and truck/off-road configurations. Although the majority of Avenger carbs have electric choke, six versions within the entire lineup are offered with manual choke. All Avengers have vacuum secondaries.
Street Avenger carbs were designed and calibrated specifically for optimal street performance, with features including a secondary metering block, four vacuum ports (for positive crankcase ventilation, power brake, spark, and vacuum accessories). The Avenger series is not designed for immediate bolt-on use with Chrysler automatic overdrive transmissions. If used with a GM overdrive TH700R4 or TH200R4 transmission, you need Holley’s transmission kickdown cable bracket (PN 20-95) and geometry corrector (PN 20-121). Depending on your throttle bracket, you also need a throttle stud (PN 20-2, 20-38, or 20-40). The Street Avenger includes a Ford automatic transmission kickdown, but not for use with overdrive transmissions.
The Ultra Street Avenger series has aluminum construction and anodized billet aluminum metering blocks and baseplate (available in various colors). The Ultra is lighter (for those concerned with minimizing weight) and comes in several anodized colors. Personally, I love the Ultra series; in addition to the benefit of reduced weight, they look way cool.
The Avenger Truck series is a unique design, intended specifically for truck and off-road applications. It has a single fuel inlet, square fuel bowls with side-hung floats, and an exclusive metering block and vent tube designed to prevent fuel spillover at extreme angles. Flood-free operation accommodates climbing angles up to 40 degrees as well as side-hill maneuvers and nose-down descents up to 30 degrees.
The “big boy” of Holley carburetors is the venerable Holley Dominator series, known as the 4500 series; it is often referred to as the “elephant” carb. The Dominator was designed as a large-airflow racing carburetor and debuted in 1969 (although some sources say 1968), initially to address the needs of NASCAR competition. Shortly thereafter, it was offered to the public. Today, the 4500 is extremely popular in drag racing applications. Versions are offered in 1,050, 1,150, and 1,250 cfm, as well as a “street” version rated at 750 cfm that was introduced basically to satisfy hobbyists who hungered for the Dominator look.
The Dominator flange is unique to the 4500 series. You must use a manifold designed for use with a Dominator or install an adapter mounting plate to accept a Dominator. A Dominator cannot bolt to an intake manifold that is not designed for its larger bolt pattern.
Float bowls and metering blocks are similar to those found in the 4150 series, but the 4500 features an appreciably larger main body with the unique secondary linkage located between the front and rear throttle bores, underneath the main body. Throttle bores have a hefty 2.00-inch diameter, compared to 4150/4160 diameters that generally range from 1.563 to 1.688 inches.
Baseplate Bolt Pattern
All Holley 4-barrel carburetors (except for the 4500 series) have a baseplate bolt pattern with the baseplate-to-intake manifold bolt holes stagger-spaced 53 ⁄16 (left to right) x 55 ⁄8 inches (front to rear). As previously mentioned, the 4500-series Dominator baseplate bolt pattern is unique to that series and includes a square bolt pattern measuring 5.375 x 5.375 inches. The Dominator requires the use of an intake manifold designed to accept a Dominator. However, adapters are available that allow you to mount a 4150/4160 to a Dominator manifold and vice versa. Depending on the specific intake manifold, installing a Dominator onto a manifold designed for the 4150/4160 carbs may require enlarging the manifold’s plenum ports.
The 4150/4160 series requires a 51 ⁄8-inch air cleaner/gasket; the larger Dominator requires a 75 ⁄16-inch air cleaner and gasket. These are the standardized published sizes that appear in all catalogs; they provide a comfortable drop-on fit. Actually, the 4150/4160 carb air cleaner inside-diameter gasket surface measures approximately 5.001 inches; the inside-diameter gasket surface of the Dominator measures approximately 7.251 inches.
Air Cleaner Threads
Most Holley carbs, including the 4150/4160 series, have a 1/4-20 threaded center hole to accept an air cleaner stud. The Dominator (4500) series has a larger 5/16-18 threaded hole. Inexpensive male/female adapters are readily available from any performance retailer to allow the use of either stud size. Adapters are available with 1/4-20 male thread and 5/16-18 female thread as well as 5/16-18 male thread and 1/4-20 female thread.
Written by Mike Mavrigian and Posted with Permission of CarTechBooks