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 Bore .60 over too much?
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Cowpatty69
Sitting Bull

USA
154 Posts

Posted - 05 Dec 2017 :  10:09:23 PM  Show Profile  Reply with Quote
Hey All, just looking for your opinions here. I recently dropped of a 1968 400 YS block (9790071) to be dipped and checked. They let me know that it was currently at .40 over and would need to be .60 over to clean it up. I brought it back home to think about it. I have a complete 557 block from a 77 TA available that is bone stock, but not near as desirable as the 1968. Is .60 over too much for a 400ish HP build that will probably be driven under 1000 miles a year? Complete 400s have really jumped in price and don't show up like they used to. Thoughts? Thanks in advance!

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GtoGuy32
Crazy Horse

USA
846 Posts

Posted - 05 Dec 2017 :  11:54:28 PM  Show Profile  Reply with Quote
Did they sonic check the walls?

If the walls are too thin, you could have cooling issues.

I know lots of guys have gone 0.060", but every block is a little different. Pontiac did pretty well with preventing a lot of core shift.
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Cowpatty69
Sitting Bull

USA
154 Posts

Posted - 06 Dec 2017 :  5:05:27 PM  Show Profile  Reply with Quote
I don't believe it was sonic tested, or at least they didn't say anything about that, but felt confident that .60 over would be no problem. I guess, all things being equal,my question is would a "good" block bored .60 over typically last the same as the original under the same user conditions?

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Cowpatty69
Sitting Bull

USA
154 Posts

Posted - 10 Dec 2017 :  4:00:55 PM  Show Profile  Reply with Quote
Well, the consensus I'm getting from my hot rod buddies is that a 60 over bored block should last quite a while under normal conditions. I did put this block out on ebay just to see if there's any interest or need from somebody doing a "numbers matching" gig. If not, I may start collecting the rebuild parts as I go.

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