I have been following this with great interest, I have broken in AB? engines completely wrong, before I knew better, completely right, and some not at all. I run several ABC type engines as Diesels which according to some operate too cool for long ABC engine life. Dub Jett says the engines have a certain amount of ability to adjust to operating at differing temperatures, if this were not true you could not fly at part throttle to just cruise or land without damaging the engine. I believe Jett also recommends starting his engines 1/2 turn rich from your normal run setting to avoid shock heating the engine, then let the engine run a few seconds to stabilize then reset to your normal setting and fly. Bob Brassel can correct me if I'm wrong here. I think I read that when Dar was challenging Bob about their breakin and start up procedure.