Accelerator Pump Arm - Plastic

The Holley Accelerator Pump Arm – Plastic (part number 20-78) is a direct-replacement accelerator pump arm engineered for 30 cc fuel pump applications in Holley 2300, 4150, and 4160 carburetors. This black plastic component controls the precision timing and volume of fuel delivery during throttle tip-in, ensuring smooth acceleration response and consistent fuel mixture across RPM ranges.

Built to OEM specifications, this accelerator pump arm integrates directly with Holley's pump linkage system to deliver a calibrated fuel charge at throttle opening. The plastic construction reduces weight compared to metal alternatives while maintaining the rigidity needed for reliable actuation under varying engine loads. At 0.1 lbs and compact dimensions (3.3 x 3.1 x 4.4 inches), the unit mounts easily within standard carburetor assemblies without modification. Proper pump arm function is critical for cold-start performance, cruise-to-acceleration transitions, and preventing hesitation during dynamic driving conditions.

This component is essential for carburetor restoration, rebuild, and maintenance work on classic muscle cars, street rods, off-road vehicles, and high-performance engines that rely on Holley four-barrel platform carburetors. Whether replacing a worn accelerator pump arm from original equipment or upgrading to ensure consistent fuel metering on a rebuilt carb, this OEM-equivalent part delivers the precision fuel delivery that high-compression and modified engines demand. Single unit shipped ready to install.