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.

http://www.toni-clark.com/english/mo...untanaS140.htm

That is a beautiful airplane. Two things strike me as odd. The exhaust mainifold is right next to the ignition box and is touching the spark plug wire, you would thing that would casue the obviuous problem. The throttle serovo is in the engine compartment. I was under the impression that was begging for RF interference. That guy obviously knows what he is about, and it works so, who am I to critique it?