When you install the gasket between the upper and lower halfs of the carbs, double check the gasket to make sure all the vent holes are clear. When the gaskets are made, sometimes material is left in place, where a vent hole should be, and if these holes are plugged, the car will run fine, but suck all kinds of gas into the motor, after you shut if off for a while. I won't bother explaining how long it took me to find that problem, but I sure don't want somebody else to go through the trouble, so double, tripple, quadrouple check your gaskets if you have to
