I have (had) a rochester that did the same thing. No rhyme nor reason to it. the float is set perfectly, and does not have a hole in it I can take the float out within 3 minutes of shutting it off, the carburetor is still full of gas and there is nothing inside the floats, I finally gave up and put the YF on I had laying around and it works fine now. But if you do ever figure out why its doing that let me know...I used the rochester for 25 years with not a problem, then....it started doing that, sometimes.....I'm afraid to try and use it again. Last time my car was in the shop for 4 days which turned into 2 weeks, I had to drive the truck in pouring rain, and the last 4 or 5 days I had to deal with the possessed carburetor.
