I have a new Tower Hobbies .75 abc that is really tight and will get the heat gun treatment for the first firing. And yes, I have broke a few car engines in with a prop (it is preferred but depends on crankshaft type sg or std threaded). It doesn't matter if it is a car, boat, or plane engine. A tight ABC engine is a tight ABC engine. The point I was trying to get across is that I preheat the clyinder, and then run them at a couple clicks rich at a normal operating temp, and do not run them at less than half throttle for the first 20 minutes or so (ABC). I fly mainly magnum, saito and YS and have never messed with a painted (sarcastic) on clyinder OS.