Carb issues

I used to own an AAR cuda, so I'm very familiar with six pack set-ups, and my superbird I have now is a six pack car. If your car has backfired through the carbs at all, I would almost bet the power valve is blown and leaking fuel... My AAR used to do this on occasion, so I always carried extra parts in the glove box. Of course it could be just a bad needle/seat. I'd pull the center carb off and check it carefully.