An engine part hitting another part of the engine is not why you break in A new engine, there should never be anything like A rod hitting the case!! Chuck, my bearings from Boca were for A 1.20 OS FS and Boca sent me an opened rear bearing and an inclosed front bearing. Then I discovered I could get my new OS bearings from my LHS. If I would have known they had them at the time I would have just gotten the OS bearings, the first set only lasted about 10 years of very hard use. If I ever build another engine for racing I would still like to try there high end ceramics but I don't think that will ever happen here.