does break in not include WOT for a small period of time? I seem to remember a log book my dad kelp in breaking the twin 60s in on the starcraft back in the late 70s.
As I recall from merc:
No extended periods at idle/below 1500 rpm
First ten hours no more than 3/4 throttle and vary throttle constantly
Next ten no more than 5 minutes at wide open. And cary throttle.
Engine is broke in at 20 hours.
I would assume like most modern vehicles that current break in procedure is more for the gearcase now than the engine. Modern ring packs seat fairly quick. And if they don't... well they don't.