• Holley 1940 Throttle Body Bushing Replacement

    When the Holley 1940 carburetor throttle shaft gets .010 or more of wear, it is time to add bushings to the throttle body. Without a run-out mike this might be difficult to measure, so estimate anything over 1/32″ in sideways action. When the throttle shaft is too loose it will…

  • Adjustments for 1968 Pontiac Tempest & Firebird 250″ engine.

    The Rochester BV carburetor is a one barrel downdraft carburetor with a divorced choke. Divorced meaning the choke thermostat is mounted in the manifold, connected to the carburetor with a choke rod. Adjustments Idle Speed & Idle Mixture Turn the idle mixture screw in (clockwise) until seated, lightly. Scoring of…

  • How the Holley 847 Carburetor Works

    Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Purpose of the Carburetor The carburetor delivers a combustible mixture of fuel and air to the intake manifold of the engine. It automatically controls the amount of fuel being mixed with the air to meet changing engine operating…

  • Testing the Holley 94 Accelerator Circuit

    When I’m rebuilding my carburetors, I will usually test the accelerator pump circuit before closing up the float bowl. The Holley 94 carburetor uses a check ball in the accelerator pump well and I want to make sure it doesn’t need seating. 1st, you need to know why the check…