ORIGINAL: Scota4570

I made an aluminum manifold for a Kiortz fourty something cc and it worked great. Maybe the gaskets proxide enough heat insulation? That engine was a fine performer until it hit the ground at 100+ mph. The crank is bent and I can't figure how to straighten it. I have beat on it and pried on it to no avail. Anyway, back to the Zenoah.

Could it be that the oil seals on the ends of the crank are old and hard? I was thinking that if tht were so when it is running they might not snap back fast enough. If the bearings were a little worn, they seem tight, but, if they were; a little imbalance, would open a gap in the seal that I don't see in the static test.