Since this thread is about AB? type engines I thought I'd show you this Russian ZEUS .61, it is hands down the tightest engine I've ever bought. Even now with 10 to 15 hours on it, it still does a good imitation of a turkey call when turned over with the glow plug out. It cannot be turned over by the prop driver even with the plug out. As you can see it is wearing a Webra carb and SuperTigre swing muffler. The original carb and muffler were small, it is not a powerhouse by any means but is an interesting engine with absolutely beautiful machine work inside and out.