GM Rochester Quadrajet - Super Chevy Magazine

The first step in any carb rebuild is taking it apart. Remove the nine screws securing the air horn, and then use a small punch to push the accelerator pump pin in towards the air horn so you can remove the accelerator pump arm and rod. After you lift off the air horn, the accelerator pump can be pulled out. Save the spring from beneath it.

The first step in any carb rebuild is taking it apart. Remove the nine screws securing the

There are several good reasons GM chose the Rochester four-barrel "Quadrajet" carburetor to fuel some of the best musclecars ever made. The Q-jet, as it has become known as over the years, is an efficient, simple, and reliable carb that is easy to tune and can make tons of power. The reason a Q-jet is so simple to tune is that it needs very little adjustment to work properly. When equipped on a new car, most of the Q-jet's primary functions were dialed in at the factory so it could work best with the specific engine it was going to fuel. However, since no car has come equipped with a Q-jet for at least 15 years, factory tuning is no longer available and you've got to make that old Q-jet work on your own.

That's where companies like the Carb Shop can help. Although well known for building trick Holley carbs, the Carb Shop is just as adept at tweaking the Q-jet for the street and the track. We stopped in at their Ontario, California, facility and peeked over the shoulder of "Q-jet Boy" Kevin Van Noy as he rebuilt and modified a customer's carb. Check out the tips and tricks he offered, and after arming yourself with one of the Carb Shop's complete Q-Jet rebuild kits you'll feel better about tackling the job yourself-or at least you'll be able to talk to Van Noy and company with a more astute vernacular. When calibrating a Q-jet's fuel curve, the Carb Shop drills and fills some of the factory holes to give your carb the best power and smoothest drivability possible.

A Carb Shop Q-Jet
If you'd rather have a root canal than rebuild your own Q-Jet, the Carb Shop would be happy to do it for you. There are also several tricks and modifications the fuel masters perform on every Q-Jet that would be difficult and expensive for the average-equipped car guy to do. Check out a few of the tricks the Carb Shop is capable of, and decide if you want to DIY or if they can redo your Q.

Removing the power piston comes next. The primary metering rods hang from the power piston, and you should be careful not to bend them when removing the piston.
Removing the power piston comes next. The primary metering rods hang from the power piston
A spring sits under the power piston and can be removed at this stage. If the spring is broken, replace it with the appropriate new spring (available from the Carb Shop).
A spring sits under the power piston and can be removed at this stage. If the spring is br
Using needle-nose pliers, lift the bowl baffle out and put it aside to be reinstalled later.
Using needle-nose pliers, lift the bowl baffle out and put it aside to be reinstalled late

Lift the float hinge up next, using needle-nose pliers. If the stock float is brass or plastic, it should be replaced with a nitrophyl float that will give your carb quicker float response time, and a float that won't sink.
Lift the float hinge up next, using needle-nose pliers. If the stock float is brass or pla
Use a wide, flat-blade screwdriver to loosen the brass seat. Lift it out with pliers.
This is the adjustable part-throttle screw, which determines the lowest position of the metering rods at cruise speed. Remove it next and inspect it for wear. If it's in good shape, it does not require replacement.
This is the adjustable part-throttle screw, which determines the lowest position of the me

Use a wide, flat-blade screwdriver to loosen the accelerator pump check-ball screw as well. Remove it with your trusty needle-nose pliers and then turn the carb upside down so the steel ball falls out. Don't lose it!
Use a wide, flat-blade screwdriver to loosen the accelerator pump check-ball screw as well
Disassemble the outside of the carb next. Remove the fuel fitting and filter. Don't throw away the spring-you'll need it later.
Disassemble the outside of the carb next. Remove the fuel fitting and filter. Don't throw
The next step is to remove the choke assembly. After removing the center screw from the choke housing, use the choke rod to hook the lever and lift it out.
The next step is to remove the choke assembly. After removing the center screw from the ch