The accelerator pump provides an extra volume of Valve seat

Posted by zjautopartsLee on February 4th, 2016

Like most Carburetor float, the center in a trio has all the normal systems including idle, transfer, main, enrichment, and choke. And in most three two arrangements, all the carburetors have the same CFM rating (some factory installations have center carburetors that were bigger than those on the ends, others used center carburetors that were smaller than those on either end).

 But while all the carburetors may look the same, there are normally significant differences in those used on the ends. Generally they lack idle circuits and the throttle valves are thicker to seal more effectively and ompletely close off airflow when running off the center carburetor only, choke butterflies are also eliminated.

One of the systems found in most carburetors is an accelerator pump. It provides that squirt of fuel when the throttle is opened and it helps with starting and preventing flat-spots in acceleration. When the throttle is opened suddenly, the airflow through the carburetor increases faster than the heavier fuel droplets can, and the engine will go lean momentarily causing a stumble.

The accelerator pump provides an extra volume of Valve seat until the main system in the carburetor can "catch up" with the demand. With three twos, when all three carburetors are suddenly opened, the function of the accelerator pumps is critical.