How long has this been going on. I had a Rochester Quadrajet on a 400 in my 68 GTO. Did the same thing...was a leaking needle and seat. After the engine was turned off it would drip fuel until the pressure bled off. The end result was a hole in the #6 piston from an oil pan explosion. Better check your oil that it's not loaded with fuel waiting for the right moment. Mine blew cranking it over at the parts store with a carb rebuild kit in a bag on the front seat.
