Quick Fuel Technology 350 CFM Metering Block Upgrade User Manual

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350 CFM Metering Block Upgrade

Installation Instructions

Congratulations on your purchase of a Quick Fuel Technology 350 CFM two barrel metering block upgrade. Advanced Super Street and Street Modified class engines frequently encounter high RPM air/fuel mixture control problems due to the air flow restriction problems. This results in dramatic changes in the air/fuel mixture throughout the operating range.

Due to the small venturi and throttle bore, the mixture gets too rich at high RPM. Efforts to compensate for this with jet change is often ineffective or creates hesitation problems due to an air/fuel mixture that is too lean in other portions of the RPM band.

The Quick Fuel Technology metering block, has been internally modified to provide a more uniform air/fuel mixture through a broader RPM band.

These internal modifications will require a different calibration primarily on the main metering jets. With this metering block we recommend using a 3.5 power valve. The main metering jets will be approximately 4 to 6 numbers higher than the stock metering block.

If you do not have a baseline main metering jet number, we recommend starting with a number 72 jet. Best jet for power and spark plug coloration from there. This is a critical step to take full advantage of this upgrade for best power and acceleration.

It may also be necessary to reduce the accelerator pump over-ride spring adjustment. If after installation, the engine sounds rough or not very responsive when you open the throttle without a load, the accelerator pump may be making the mixture too rich. Try compressing the accelerator pump over-ride spring, even to the point of virtually no accelerator pump shot at low RPM. This adjustment is made by tightening the nut and bolt on the end of the accelerator pump arm to the point where the pump arm floats freely at idle. Since most track rules will not allow you to change the accelerator pump nozzle size, this is a trial and error adjustment to obtain the best throttle response for your engine.

Again, we thank you for purchasing a Quick Fuel Technology metering block upgrade. If you have any questions regarding the performance of this product or any fuel system problems, please feel free to call us.

P/N 99-25

© Quick Fuel Technology, Inc. 2000