[crm318]

i just aquired a 78 cheyy van that i could barley get home due to a shot accelorator pump (qjet). i rebuilt the carb and there is a day and night difference in performance. the only thing is that there is a stumble on acceloration. i have rebuilt 9 qjets successfully and everything in this one was fully referbished. the motor is all factory and i set the timing to 8 degrees. if i punch it from a stop, it misfires and falls on its face. if i feather it slightly and then give it juice, it has great power. what might cause this stumble?