In article ,
john smith wrote:

When breaking in a new or rebuilt engine, does it matter if you run high
MP/low RPM or high RPM/low MP at 70-75% power?


Yes -- you want to exert enough pressure on the ring/cylinder interface
to achieve a lapping effect between the two. Actually, you could
maintain 75% power for breakin. Normally, you want to be 25"/2500 for a
normally-aspirated engine.