Expert: Brad Sears - 12/24/2007

Question
I have a 1960 - 283V8 with a Rochester 2GV carb (there is no tag but looks like the 2GV in the manual)The engine runs good but when it is not running for several days the gas leaks out of the carburetor.  I rebuilt the carb and it stills does it.  I have put the carb on the work bench, filled it with gas and I can not find where the gas goes.  I can not find any gas leaking on the bench.  The carb has been soaked in cleaner and cleaned inside and out.  I do not see any capillary siphoning.

Answer
A lot of these problems that appear to be carburetor leaks are actually percolation on hot shut down. To eliminate this check the exhaust heat valve on the exhaust manifold and make sure it is operational. Other wise the hot exhaust is routed into the floor of the exhaust manifold when the engine is running at normal operating temperature. Heat is only supposed to be routed to the floor of the intake manifold during cold start up to eliminate stalling. That carburetor is supposed to have an anti perk valve on the top of the float bowl. Make sure that is adjusted correctly. Check these and get back to me. Good Luck.
Brad