Owners manual

5
Figure 7
GENERAL INFORMATION:
A. FUEL PRESSURE: This carburetor has been designed to work best at fuel pressures between 5 and 7 psi. Holley recommends 7 psi at
idle, and a minimum 4 psi at engine redline. Three 8” fuel lines can result in adequate (indicated) fuel pressures, but restricted fuel flow.
Use of a Holley electric fuel pump at the rear of the vehicle next to the fuel tank assures adequate fuel pressure under even the most
severe operating conditions.
B. ADJUSTMENTS:
1. Fuel Level: On level ground with the engine running, remove the primary and secondary fuel level sight plugs. Loosen the lock screw
and turn the adjusting nut clockwise to lower the fuel level and counterclockwise to raise the level. Fuel level will be properly adjusted
when the fuel begins to trickle out of the sight hole. Tighten the lockscrew and replace the fuel level sight plugs. See Figure 4.
2. Accelerator Pumps: The “trick” to extracting peak performance from a “double pumper” is to get the pump shot delivered at the exact
rate that is required by the engine. This rate is affected by the pump discharge nozzle size and the pump cam profiles. This
carburetor has been calibrated for the most “typical” applications. Added performance can be obtained through “on the vehicle“
testing. Necessary parts and tuning instructions are available in Holley TRICK kit P/N 37-933. In all cases, it is necessary that the
slightest movement of the throttle lever results in movement of the pump operating lever. This is adjusted by compressing or relaxing
the pump override spring as shown in Figure 8.
3. Choke: If the fast idle speed provided during the choke operation needs adjustment, turn the engine off. Close the choke exposing
the fast idle adjusting screw. Use a small open end wrench for ease of adjustment. See Figure 6.