My car is 71 GS 350 auto. The carb model # is 7041540 MF 1391. In looking in the service manual, this carb is for 455 engine auto trans. I also noticed that the top portion is different in color than the larger lower portion. I do not know what the previous owners did to the carb and I am assuming that it was replaced some where along the way. Going in the shop tomorrow to determine why the warm start is so difficult. I assume that the 455 carb works ok on a 350 if this is the case. Any comments or suggestions.
The carb. you have is in fact a '71 455 carb., rated at 800 cfm.. The correct carb. # for the car is a 7041544, rated 750 cfm.. Either will work fine based on tuning/jets etc.. by a knowledgeable carb. guru.
To answer the question posed, as to what might cause an extended warm start, typically flooding is what causes that. There is a phenomena called hot soaking. When this occurs, the fuel oin the bowl gets very hot, causing vaporization, and flooding the air cleaner with fuel vapor. One other related situation is caused when the engine starts, and the fuel in the bowl is replaced with the cooler fuel in the tank, but preceeded by the hotter fuel in the lines and pump. This situation is not carb sensitive, but fuel sensitive, and a different fuel MAY help. In both cases, the hot fuel, boiling in the bowl, cannot enter the fuel metering devices, starving the engine for fuel. I have also seen the choke not open completely, causing flooding. Usually, an extended hot start is caused by excessively rich mixtures. Ray
