Mr. C,

Thanks, again, for good info! Agree mostly, and only regret I was too otherwise busy in the early 1980s to hear of Mats Boehiin's conversion heads. They sound good!

The hi-temp O-ring heads do very well on engines designed for hi-RPM glow operation, AND also seem to enjoy turning heavier props at lower RPM ( a lower compression setting condition, too.)

A comment above I couldn't locate quickly enough to quote, mentioned considering Cox early, inexpensive reed versions as of short life expectancy - Kleenex engines, IOW. They weren't, but in their price and performance range, many didn't expect more than that. So they handled their engines in a quickly destructive manner.

Start with a prediction then make sure the results match your prediction. Warp and skew the facts until they do, IOW. We have too much of that today in supposed "science," in too many other areas. The precision of Cox engine production then, and probably even now, was/is excellent. Abuse is abuse.

E, g., today, some high precision engines do better with NO castor in their fuels - ever. Many traditionalists still insist on some % castor, then blame the engine when it runs poorly... I'm uneasy running an engine with NO castor in the fuel, but I'll take the word of the guy who spent the time, money and effort to develop his engine, then stake his reputation on it.

You may have noticed a few posts here, or in other engine-related forums (ACK, that should be fora - I know, I know...) people complained that a highly regarded engine did not work well for them. It blew bubbles around the head and the backplate, wouldn't idle, was hard starting and short on power. Did they ever think to check that the factory assemblers actually did tighten the assembly bolts correctly? It's better today than in days of yore, but still rates a check to confirm...

When all else fails, read the instructions...