I had a post on here a week or so ago about a blaster with msd tl #4270. I have a 5mm stroker crank and could not get it to run.. Thought it was the tl because of the backfiring issue. switched to stock ignition and still backfiring. took a quick look and marked tdc for each cylinder and they did not appear to be 180 deg apart. Is this a common repair on a stroker crank.