[Tim Corcoran]

I have to ask, did you use the same machinist each time you rebuilt the engine? Gapless rings are a little finicky I know I have used them in the past. They need a special finish to work correctly. For a street car there is no advantage to use them. They actually work best with a vacuum pump. I agree the rubber plugs for the breathers should be completely open. Was a torque plate used when your engine was honed? By the way a header evac system only works correctly with open headers. If you decide to re-ring the engine I would get a different machinist and ditch the gapless rings. Have you tried backing the timing off 2 or 3 degrees and see if it makes a difference?