Vizard’s Super Tune/Modify Holley Carbs (Performance How-To)

The Holley carburetor is an icon in the performance industry. Thirty, forty, even fifty years ago, if you looked under the hood of any modified or performance car, you more than likely would discover a Holley carburetor lurking there. Often, many enthusiast’s first modification is swapping out the factory induction system for a new Holley 4-barrel carb and intake manifold.

While many of today’s modern cars have moved past carburetors and into high-tech fuel-injection systems, most cars from the highly collectible eras are still running carburetors. Carbs are comparatively inexpensive, highly tunable, and do not require laptops, expensive tuning equipment, or computers to function. And by far, the most popular carb still in use is the Holley carb.

In David Vizard’s How to Super Tune and Modify Holley Carburetors, best selling author Vizard explains the science, the function, and most important, the tuning expertise required to get your Holley carburetor to perform its best for your performance application, whether it’s street, strip, supercharging, or race applications. Holley has been a best-selling subject for years, and this much-needed update guides you through the traditional 4150 Double Pumper, Dominator, and 4160 vacuum secondary models, as well as all the recent releases from Holley, including the Ultra Street Avenger and Ultra HP Series Carbs.

With its high degree of tuning ease, and with all the new models coming into the market, the knowledge of an expert like Vizard is a requirement to meet your performance goals, now more than ever. This book is an essential addition to any hot rodder’s library.

From the Publisher

In David Vizard’s How to Super Tune and Modify Holley Carburetors, best-selling author Vizard explains the science, the function, and most important, the tuning expertise required to get your Holley carburetor to perform its best for your performance application, whether it’s street, strip, supercharging, or race applications. Holley has been a best-selling subject for years, and this much-needed update guides you through the traditional 4150 Double Pumper, Dominator, and 4160 vacuum secondary models, as well as all the recent releases from Holley, including the Ultra Street Avenger and Ultra HP Series Carbs.

Operating Principles

The arrow indicates one of the two PVRCs, which feed extra fuel into the main jet well to enrich the full-throttle mixture. This particular metering block is from a high-performance Holley carb, and utilizes threaded jets for optimum calibration.

Carburetor Selection

Shown here with a Dominator, this Chevy big-block 572-ci engine proved to be capable of more than 750 hp in street trim with a 4150 carb (850 cfm, PN 0-80531). This was a case of knowing how to utilize the CFM capacity of the carb to the fullest extent.

Booster Science

Although the stepped dog-leg booster (arrow) has only marginally more gain than the regular dog-leg booster, the step brings about better fuel atomization. This style of booster is about the most versatile currently in use and is a good choice if fuel atomization appears to be inadequate.

A 406 (6.65 L) Chevy small-block powers my 1980 Pontiac Trans-Am. The 550-hp engine utilizes a highly modified Holley flowing about 1,020 cfm. The editor of Motor magazine tested the car and as seen here it delivered 0-120 mph in 12.5 seconds along with perfect street manners.

Idle and Transition Calibration

To supply the required amount of idle air without using up all the transition slot, it may be necessary to drill holes into the butterflies.

Full Power Circuit Calibration

The point to note here is how the flow efficiency rises as the seat is given even basic modifications to streamline the approach and departure shapes.

Accelerator Pump Circuit Calibration

The complete accelerator pump system can best be seen from below the carb flange. When the throttle lever (A) is opened, it rotates the cam (B), which lifts the lever arm (C). That in turn compresses the spring (D), which then pushes the pump diaphragm lever (E).

Publisher ‏ : ‎ CarTech
Publication date ‏ : ‎ October 2, 2013
Language ‏ : ‎ English
Print length ‏ : ‎ 144 pages
ISBN-10 ‏ : ‎ 1934709654
ISBN-13 ‏ : ‎ 978-1934709658
Item Weight ‏ : ‎ 1.05 pounds
Dimensions ‏ : ‎ 8.5 x 0.38 x 11 inches
Part of series ‏ : ‎ Performance How-To
Best Sellers Rank: #60,811 in Books (See Top 100 in Books) #4 in Car Customization #14 in Vehicle Owner’s Manuals & Maintenance Guides
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