Join Date: Aug 2006
Location: Greater Puget Sound Area
Re: Holley accelerator pump diaphram
Upgrading to 50 cc accelerator pumps is a common way to handle off idle bogs.
If the carb was a bit on the large size for the engine it was used on it might have been necessary to upgrade in order to make the car accelerate quickly and smoothly. It is also common to change to larger shooters (or drill out the stock units) to go along with the larger pumps. that way you can force more fuel in the engine until the rpm brings the flow up to where it is ok.
Mind you - this is a patch at best and results in a very rich off-idle mixture. The proper fix would be to select a carburetor that was better sized for the engine and tune the IFR to assist the off-idle fuel supply in relation to actual demand.
66 Mustang Coupe. 365hp, 4spd Toploader, sub-frame connectors
Shelby drop, suspension tuned for slalom and hill climb
body mods and weight reduced to 2000lbs; name: Muskrat