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Carb Class: Needle & Seat / Fuel Pressure

Carb Class: Needle & Seat / Fuel Pressure

Pressure vs. Volume is something a carburetor is dependent upon for proper operation - PRESSURE DOES NOT = VOLUME. Generally speaking, as pressure increases through a needle & seat assembly, the volume will decrease. Increased fuel pressure leads to issues like aeration, fuel spray and starvation. One thing we like to remind people of is the fact that your float has to overcome whatever your fuel pressure is - If your pump and regulator are set at 10 PSI, then it will take 10 PSI to shut off the needle. Some float designs and materials are not capable of this. Combine that with a shortened lever and the problem compounds itself.

We recommend setting your fuel pressure to 6.5-7.0 PSI for best performance.

Proper float level on a Quick Fuel Technology Carburetor is set with fuel pressure falling between 6.5-7.0 PSI. Once you are sure of your fuel pressure, then it is a matter of adjusting the float height using the adjustment nut. Start by loosening up the lock screw (turn counter-clockwise) a half turn or so to free the adjustment nut. Once free, move the adjustment nut to raise or lower the float - clockwise will lower the float and counter-clockwise will raise the float. With proper fuel pressure the fuel level should be halfway up the sight window - once satisfied with your float level don't forget to tighten the lock screw and wipe away any excess fuel.