ChevTech84

I am helping a friend rebuild his 87 TA's 305 motor. Everything checked out good during the teardown except for a weird pattern in the rear main cap. It's rougher than any bearing saddle i've ever seen, usually a spun main leaves a large gouge where the bearing tangs line up around the entire cap. Never saw anything like it before, engine has never been rebuilt before either. Anyone know what this may be?

Vader

Wierd pattern? Rough? These are all pretty subjective terms. Can you post a photo or describe the surface any differently? Does the pattern look like factory I.D. grinder or machining marks? I've seen some caps whose surfaces are not what I'd call "pretty" by any means, but usually from the factory machining and not a spun bearing. Usually spinning will leave circumferentially polished/gouged trails with some galling in severe cases, as you describe.

ede

what mr. vader said, post a pic

ChevTech84

Wish I could post a pic, no scanner. It just looks rougher than the other caps which are perfectly smooth. If I run my fingernail across it, it does not catch at all but defineately course in appearance. I have only seen one rear cap spin and they were all
spun in that motor. No metal in the motor upon teardown and no noise when it ran. Bearings are a tight press fit with no damage on the back side of them. Just haven't seen any saddles look like this before.