I have an old .75 two cycle glow Tower Hobbies in an also old Great Planes Super decathlon. I would like to transition to a new good 4 cycle, or better gas engine for it. Which would be a good size equivalent to my old engine?

A 20cc is the same displacement as a 1.20. Saito has some four stroke gas engines that are smaller than 20cc but are pricey. If you can make a DLE20 work balance wise it's a good place to start. Be prepared to do surgery on the firewall. To got a DLE in there you will most likely have the carb sticking through a hole in the firewall.

David

I have heard the Towers 75 is a powerful engine, so I would say, if you go glow buy the Saito 100, and if your 75 was more powerful than you need buy the Saito 82.

Jim