Largest CID from a 350 block? - Team Camaro Tech
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post #1 of 5 (permalink) Old Oct 3rd, 04, 03:14 AM Thread Starter
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Dave M
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I have two small block blocks and I'm contemplating building some type of stroker motor for my 69. I know all about 383's and realize that is a great way to go but what is the biggest cubic inch I could safely get from a 3932388 (standard bore) or a 3970010 (already .040 over) block. The 010 block is the high nickel block.

I plan on buying a new rotating assembly and starting from scratch and this motor will be street driven almost daily.

Dave Miller

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post #2 of 5 (permalink) Old Oct 3rd, 04, 06:25 AM
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I believe the largest you can go is 391/395ci. This will require an offset ground crank. They are not very popular engines and the durabilty becomes an issue. I hear they work well for very mild builds but, not for performance applications. You would be much better off with a 383, 385, 388 (all the same except bore size) 3.75 stroke. I think that's about the limit of factory 350 blocks.

Royce (NO XQSSS) Bradley

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post #3 of 5 (permalink) Old Oct 3rd, 04, 10:40 AM
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A 4.060" bore and 4.00" stroke would get you 414". I would never do it though as you would need to do a lot of special stuff to get it to work - .800" small base circle cam, 2.00" or even 1.88" Honda style rod journals, short fill the block, serious grinding on the oil pan rails, etc.

Even after getting an engine like this together there would be some inherent reliability problems. Very short piston skirts would be prone to rocking in the bores and premature wear, poor rod to stroke ratio, and more . . .

It would be a ton cheaper to just buy an aftermarket 400 block, build a 400, and be done with it. Unless you were racing in some odd ball class that required a 4.00" bore I can't see any reason to ever do it.

IMO 383 or 388 would be right about the max I would ever do with a 350 block. Although you might be able to make a 3-7/8" stroker work (that would make an SBC 396) . . . 3-7/8" stroker is fairly common these days to do with a 400 block to make a 420" motor so the parts would for the most part be available (pistons might be hard).


PS. ever get that roller cam in?

E85 racer and E85 carb builder

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post #4 of 5 (permalink) Old Oct 4th, 04, 07:37 AM
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Reliably the biggest stroke I would think is the 3.75" 383 (385, whatever)

GM has a 3.8" stroke crank used in their 383 (@ stock bore) crate motor. Not sure how easy that would be to get ahold of.

Past that I would want an aftermarket block....

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post #5 of 5 (permalink) Old Oct 4th, 04, 07:58 AM
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if you have a late model one piece seal block, there are a few places that sell blanaced 396 kits or even short blocks. actually, i think they might use an old style 2 piece seal crank with the adapter for the one piece seal blocks, so it could be used in an old block.
but really- why go thru the hassle of stroking a 350 when you could rebuild a stock 400 that is already bigger and looks identical?

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you have to make it up on the spot.

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