He's probably got the rings for it, or at least he has the dimensions because he has made a bunch for that size Echo engine for me. But there are two different, (if not more) size rings that it could be, and he has had too much problems with rings not fitting to accept dimensions from people he doesn't know well. I just send him the dimensions for all kinds of engine applications and he makes them and sends them off. If they don't fit because one of my measurements might have been 1/2 thousandth off, I just "massage" them till they do.

But anyway, you'll like his ring(s) for sure. Usually I just use one of his rings in the top groove, and a stock ring in the second groove on two ring engines. The optimum for power and longevity would be two of his rings, but I don't think I would live long enough to wear out an engine on an airplane and I am not out for the very last ounce of power, so I just use one..... They still run great and far better than even a new stock ring.

I'm sure your dimensions are right. It is probably an FPE Echo engine and they used the 21cc engines. The 23.6cc engines are more powerful, but much harder to find, especially the mid to late '90's ones that were the best. (Yes, I have some hidden away for my personal use!!) (Besides the three I have on flying airplanes!)

AV8TOR