Quick Fuel Technology 500 CFM User Manual

Installation and Tuning Instructions

500 CFM Circle Track Two Barrel Carburetor

Thank you for purchasing a Quick Fuel Technology 500 CFM carburetor for circle track applications. We have tried to incorporate many of the same features used in our highly successful Sportsman, Late Model and Super Truck Series Two Barrel carburetors. These upgrades will save you a great deal of time and inconvenience often required to convert a stock carburetor for circle track use. Fuel flow and float level control are two critical factors in achieving good on-track performance. Your carburetor is equipped

with a “state of the art” molded float that ensures fuel flow no matter how hard your car

or truck corners. Your carburetor also is equipped with a “shortie” vent whistle to

prevent fuel slosh exiting the fuel bowl through the vent tube.

1. Always use the flange gasket provided with your carburetor. Using the incorrect

flange gasket often results in substandard performance.

2. If your racecar or truck is not equipped with a positive wide open throttle stop please

consider this inexpensive device. The throttle lever is welded to the throttle shaft, however, repeated wide open throttle use without a positive stop will eventually begin to create slop in the throttle lever, resulting in inconsistent performance.

3. Always check your accelerator linkage to be sure it is pulling the throttle lever

straight. Any variation from the correct alignment will cause side loading of the throttle lever and shaft, causing premature wear.

4. We recommend the use of a spring mounting bracket that bolts to the throttle body

and ensures a straight horizontal spring pull on the throttle lever. Your carburetor has been modified by tapping a ¼”-20 hole in the throttle body to accommodate this bracket. In addition, you may have to remove or straighten the solenoid tab on the throttle lever to allow you to connect the return springs (always use two (2) for safety reasons) to the large eye in the throttle lever.

5. After installation and initial start up, allow the engine to reach operating temperature.

Once the engine has reached operating temperature, with the engine running, check the float level by slowly removing the fuel level sight plug. Have a shop rag handy to catch any excess fuel that may leak out when you remove this plug. Although we have already set the float level, the level will vary from one application to another due to changes in fuel pressure.

6. If the float level needs to be changed, with the externally adjustable needle and seat.

Caution: the adjustment nut and lock screw are directly exposed to fuel under pressure. Slightly loosen the lock screw (less than 1/8 turn) and turn the adjustment

nut (5/8” wrench) to raise (turn the nut counter-clockwise {left}) or lower (turn the nut clockwise {right}). Caution: as you turn the adjustment nut, continually retighten the lock screw to minimize fuel leakage.

7. Adjust the idle mixture screws to achieve the best idle quality.

8. You are now ready to try out your new carburetor. Your carburetor is equipped with

# 72 main jets, a #45 power valve and a #28 accelerator pump discharge nozzle.