[Steve R]

Fixit,
I agree. The eroded areas look as if someone pointed a torch there. Yes, it seems to have been very hot there.
I have not been back to measure the ring gap yet. I know one of the jobs of rings is to transfer heat fom the piston to the cyl wall. What would stop them from doing that?
Have you ever seen erosion in that area before? I haven't.
Steve