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Discussion Starter #1 (Edited)
My crank was micro polished by the machine shop and they marked the mains as STD. I know their are 5 different size bearing so I asked them how they could say it was STD. Well--- The Manual they are using only lists' the largest and smallest Diameter allowed.

I measured the main and rod journals and that is where my problem is.

The smallest allowable diameter for the main is 2.3620

My journals are range from 2.3618 to 2.3616. So it is .0002-.0004 undersize. The manual says to replace the crank or have it turned down for a undersized bearing. The shop says that since the crank is fire hardened, they would not recommend turning it down.

My problem is---- I think a size 5 bearing which has a thickness of .0788-.0789 will still give me a clearance of .0012-.0019 because the block has 2,2,2,2,2,1,1 (2.5206-2.5211)for the cap sizes.

According to the Chart in the TSRM a #2 bore + a #2 journal = a #4 bearing.

So a #2 bore + a #3 journal = a #5 bearing

Has anyone ever done this? Anyone have any experience with this? A new crank will cost 800.00+, but I have learned that the TSRM(BIBLE) is seldom wrong.

Thanks for your replies,

Dennis
 

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Discussion Starter #3
Thanks for your reply.

I have checked the journals and bore about a zillion times. I am sure of my numbers.

What I am unsure of, is using a crank that is .0002" out of spec. I think it will work, the math says it will work, but the book says "don't do it".
 
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