dfoley, we rebuilt the carb (or I should say partially rebuilt) the carb on my dad's old 1957 Ford 900 (actually 981) quite a few times. The problem with many of the rebuilt kits is that the float needle valve comes with a rubber tipped seal that sometimes gets stuck in the seat if it sits for a while. We eventually went back to the valve that was all brass, but had to do that twice since one of the old ones leaked. Pretty sure you're having the same sticking problem. Sometimes rapping on the carb worked, but often it didn't. If you have an old brass valve, and it's in good shape, I'd put that back. If you end up with carb overflow or flooding problems, it's probably not sealing well. Good luck!