If you have an original 216 or 235 the timing should be set to the ball while running. Is that what you mean by zero degrees?
I would be checking the operation of the accelerator pump. It has two springs and sometimes it will hang up a bit. You should be able to see a little stream come out when you tweak the throttle and it is not running. Also the early carburetors had a check ball right in the pump bore.
Last edited by truckernix; 09/30/2009 2:40 AM.