[simonjrwinter]

As an Update, I just received this from probe pistons.

"Simon, we run our pistons with skirt to wall clearance .003 to .0035. I
would say that perhaps your machinist measured the pistons in the wrong
place or measured the bore wrong. I have customers that are running the
pistons at .002 clearance with out a problem on naturally aspirated engines."

As my machine shop has measured the clearances at .0032, then it seems I'm stuck with nothing to do except paying out more money for pistons that might do the same again !!!