I have had this happen a couple of times, and it had to do with the carburetor float and needle valve. The first time it happened I had put on a new fuel pump, and missed the fact that the old pump had a filter, and the new one did not. This resulted in a piece of trash getting caught in the needle valve, and the carb then overflowed with gas. Second time was when a hole developed in the float, it "sank" and too much gas in the carb again..

Other typical place to have a leak on the rochester B carb is at the fuel fitting in the body of the carb. The fitting won't seal at the carb because the pot metal of the carb has become damaged. Teflon tape will not help or can make the problem worse. Easy fix is to "glue" the fitting in place with a thread locker of epoxy.

Kurt