When I started this thread my guesses were:

"Is this type of distortion caused by high compression with too much nitro, i.e., pre-detonation? Could using an electric starter on a flooded engine cause this?"

It looks like my initial reasoning was about right.

I ordered a rod and ring; I'll probably replace the bearings, too.

I have the perfect project lined up for this engine:

http://www.rcuniverse.com/forum/m_6146821/tm.htm

I even had a few rib sets laser-cut to make the build go faster.

David