Hope some one could help me out on this problem i have a 305 sports coupe with a LG 4, have taken all smog gear off added headers quick fuel 600 carb wit vacuum secondaries performer inlet manifold what happen when go out stop and leave it for say 30 mins start up is ok leave for an hour start it and it runs like a bag of **** for few minutes i thought i had carb percolation so i fitted a spacer that also went underneath the float bowls i have checked for air leaks but found nothing i started it up yesterday it was ruining rough so i adjusted the mixture to make it rich on the pasangers side and it started to run smooth it will start up hot how ever long you leave it with no problems but its now running to rich and smells any ideas would be grateful thanks

 

Which headers? Do you have a return style fuel pump? If not get one. I definitely feel your pain. My hooker 2460s run right next to the fuel line and cause this issue. Going to reroute the line when I get a chance to put the car on a lift this coming week. It's the only fix I see possible. I insulated the line where it is next to the headers, tried an insulating spacer for carb and a shield, I blocked the exhaust crossover all but a 1/4" hole, a phenolic mount plate for the fuel pump. Made things better but when the ambient temp gets over 80* it returns.

 

Thanks for that Joe i have headman headers fuel line is not getting hot also have a return on the fuel pump, I would of thought that if it was carb percolation riching the mixture would cause it to run a lot worse i was wondering it the vacuum tank my have something to do with it what do think ?