Help me please. I just got my engine rebuilt and back in the car. ( YAA ) But no matter what I do it has been hesitating during exceleration, backfireing every-so-often and poping bac k through the carbs. The engine is timed right, it has a new timing chain, the spark is advancing, all new components on the distributer, and the carbs have been balanced and mixture adjusted. Anyone have a clue for me?