Chevy Carburetor Rebuild - Quadrajet Performance Lives!

Here's How To Make Your Factory Carb A Serious Player

Mike Harrington Oct 18, 2007 0 Comment(s)
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Everyone vividly remembers their first vehicle. Mine was a 1973 Camaro. As we all know, a 17-year-old with a Camaro is often like a monkey with a machine gun. But that's a story for another day. One of the things about that Camaro that I remember most was trying to tune the Quadrajet carburetor that never seemed to work, so I enlisted the help of a friend.

At some point in our lives most of us have had a "friend" who claimed to know how to fix our car-but in that special, not-at-all-helpful-preemptive-strike kind of way that usually ends up with disastrous results. Such was the case with my Camaro. It ran worse after he played with the carb. My buddy informed me that my carburetor was junk and that I needed a new one. That sounded reasonable to me at the time. After saving all my hard-earned minimum wage money, I was off to the local speed shop to buy my new intake and shiny new performance carb. That tired old Q-jet was history!

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For those who want to dive into the complex world of Q-Jet rebuilding, might we suggest good Car Tech books to look at before starting. The first one is "How to Rebuild and Modify Rochester Quadrajet Carburetors," by Cliff Ruggles. From the simple rebuild all the way to the complex, this book has it documented. The second book "How to Build Horsepower, Carburetors & Intake Manifolds" by SUPER CHEVY contributor David Vizard, though not as extensive as the first book mentioned, has several pages dedicated to your friend, the Q-Jet.

By a show of hands, how many have had a "pal" tell us that the OE Quadrajet is junk? Generally speaking, the Q-Jet was never meant to be a performance carburetor, though it was installed on thousands of factory musclecars, including 327-, 350-, 396-, 427- and 454-inch Chevys, the 350/350 and 427/390 Corvette engines, and the Pontiac 455 H.O. and 455 Super Duty mills. And during its 25-year life span the Q-jet carb was installed on more four-barrel GM vehicles than any other model of carburetor.

During those two decades of production, the Q-Jet underwent several changes, far too many to list here. Sometimes the changes were good and other times ... not so good. The unique design of the small primaries and larger secondaries stayed pretty much the same throughout its casting history.

While the performance aspect of the Q-Jet debate goes on, just ask any NHRA or IHRA racer how well they can really perform. Those racers who compete in the Stock and Super Stock class can attest to the fact that the Q-Jet carburetor is very capable of producing gobs and gobs of horsepower, enough to go 9s in a quarter-mile. It should also be noted that Edelbrock manufactured its own version of the Quadrajet, which was more performance oriented and flowed up to 850 cfm.

To find out how to make one of the puppies bark, it was decided to make a trip to the experts at The Carb Shop in Ontario, California. The technicians there have cut their teeth building and rebuilding performance-oriented carbs of all makes/models for years. In the process, they have created a rock-solid reputation among racers and horsepower junkies alike. When they told us they could prove the Q-Jet's value on a dyno and compare the numbers to other popular models, we jumped into the briar patch to take a look.




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