The engine does not start. when i try to start it, it turns over and then backfires out the carb. I made sure the firing order was right about 3 times and it still does this. dont tell me to see a professional mechanic because i am one, i just cant seem to figure this one out. a little help would be nice. This is a car i got from a friend and he said its the piston rings, however he is an idiot so I'm not sure if thats correct.