[jhirasak]

GAZ64,

In my case, the pump exhaust valves that were provided with my new Webers all had a 00 bleed. This is a blank or closed exhaust valve and the gas inside the pump chamber has nowhere to go except out of the pump jet and into the throat of the carb in the event that the gas was heated above the vapor pressure of the alcohol that is currently being added to pump gas. By using a bleed valve which has a .50mm opening, any slowly expanding gas inside the pump chamber is allowed to return to the float bowl instead of dripping into throat of the carb.

Additionally, I have doubled the gaskets at the base of the carbs to reduce the amount of heat transfer from the manifold to the carbs. I also took the precaution to add an electric fuel pump that I could shut off some time before stopping the car to reduce the level of gas in the carbs. Some or all of these measures now appears to have corrected the problem of raw gas dripping into my engine after hot shutdown.

John