Holley Acc. Pump Cam Kit

The Moroso Holley Accelerator Pump Cam Kit (MOR65531) is an essential tuning component for carburetor enthusiasts and engine builders working with Holley 2300, 4150, and 4160 carburetors. This color-coded cam kit allows you to precisely control fuel delivery during acceleration transitions, directly affecting throttle response, off-idle performance, and overall drivability. Whether you're fine-tuning a street engine, bracket racer, or high-performance build, selecting the correct pump cam profile is critical to achieving seamless acceleration without stumbling or hesitation.

The accelerator pump cam operates by converting rotational throttle shaft movement into linear plunger travel, controlling the rate and volume of fuel delivered to the venturi during transient conditions. Moroso's color-coded plastic cam design enables quick visual identification when swapping profiles to dial in your carburetor's fuel curve. The included screws ensure secure installation, and the kit's compact dimensions (3.75 x 0.65 x 5 inches) make it easy to store or transport between tuning sessions. Different cam profiles produce varying fuel delivery slopes—aggressive cams suit high-vacuum, low-speed engines, while milder profiles work better for higher-RPM or mechanical secondaries applications.

Mechanics and performance tuners benefit most from this kit when diagnosing or correcting hesitation, bog, or flat spots off idle. Installation requires only basic hand tools and takes minutes—making it ideal for experimentation during dyno tuning or on-track calibration. The Holley 2300, 4150, and 4160 platform compatibility covers the vast majority of street and racing carburetors in circulation, from classic muscle cars to modern restorations and vintage sprint vehicles. If your carburetor exhibits poor throttle response or fuel delivery inconsistency, swapping the accelerator pump cam is often the first and most cost-effective solution to achieve crisp, predictable power delivery.