From what I understand the crank is what changes rotation of a motor and the fact I have always had a revers starter and everybody is saying I need normal rotation starter now?

Yes starter is new, had it fixed and was popping and back firing so figured they changed armature changing rotation. They gave me another starter that turned other direction and still have popping and back firing. I'm guessing I need old starter back ad recheck firing order and timing.  Just confused cuts nobody has told me wat rotation is on reverse starter, or I missed it