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sonic checking showed i have a good standard bore 400 block(.369top,.374middle,.376bottom). all bores read the same. how many thou needs to be left in cylinder wall after being bored as a minumum? thinking about boring.060 to clean up enough,but would like some left for future use. thanks

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That is a exceptional block The best 400 block I've seen(12 to 15 only) had no more than .250 thick in the major thrust side and then had less than .190 on the minor thrust sides, some as thin as .120 If you decide to sleeve the bad cylinder in your old block ask the shop to use a ductile iron sleeve, have them install it before doing any other work and then pressure test the block on the side that has the sleeve before doing any thing else to the block Don't ask why I'm suggesting that If your machine shop does not know how to install a sleeve in a block without distorting the cylinder walls next to the sleeved cylinder have them bore it to the next oversize you can get piston rings for after installing the new sleeve

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the 4.150 stroke would be easier on thrust side. should last a long time

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With those numbers i'd have no worries going 4.750" stroke using a tiny rod. .....0.250 thrust (pas side) is not considered the 'minimum' , some blocks out there are considered good @ .190 , you have a very good block sitting there regards cylinder wall thickness , saddle area may be something else to look at.

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ok,but whats the minimum allowable thickness? the 400 lost a rod and damaged one cylinder. the guy that checked it sugested having it sleeved. it does'nt look that bad to me,just beat up on the bottom of the cylinder. i can't see with the naked eye,but he said their where some holes in the cylinder wall only seen with the magni flux. i thought maybe a .060 over bore would be enough to clean this up.

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lookin to make 700-750hp with it. [8 sleeves and block filler short pour/quote]

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Id be very suspect of those numbers. Especially when you state all bores the Same

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I doubt the accuracy and usefulness of the numbers you were given. Sorry.

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Id be very suspect of those numbers. Especially when you state all bores the Same

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I doubt the accuracy and usefulness of the numbers you were given. Sorry.

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the block has not been tanked yet. wanted to get it mag'ed and sonic checked first.

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its either the same or he only measured the thrust side,but what would it matter. would'nt the thrust side be more important anyway?

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Dave,
The thrust side may be more important, but if the non-thrust side is .080" it doesn't matter how thick the thrust side is, you can split a cylinder just as easily....... don't ask me how I know.....

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here's the numbers i got.

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Both banks are exactly the same......... Sorry, but those numbers are better than most after market mopar blocks.......bs I say.

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Has anyone ever noticed, that #1 cylinder on a B or RB always seems to be the thinnest, at least on the blocks I've had done through the years? I've only done half a dozen or so but just curious if anyone else has run into that.

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Yes, Ronny, I have tested some, and it seems that #1 is thin on the thrust side, and number 8 is thin on the other side, it sees to be a pattern on the blocks that I have measured. The other cylinders seem to be more even. Could be a consequence of the way the cores are placed by some sort of machine? (I do not know the process).I better go with alublock and machined sleeves...(LOL)

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i'm hoping to get some accurate numbers from MM next week.

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Tell them you're going to publish the results on Moparts. That might prod them into giving you good service. They have a reputation to repair.