350 sbc to bore, how much?

Can i use a oversize block bore of 60 thou to build a high horse power motor (600). i have a motor that needs to be bored to 60 thou. it will be mainly used for the street and sometimes at the strip for a test. i would also like to stroke the 350 to a 434 if possible. The block is 350 h block. any help please.


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Better to find another block. Start with the '87-up, they tend to clean up at 20 over. Plus they have provisions for roller lifters.
A 350 at 20 over, with a maximum stroke of 4", makes 406, not 434. A 434 is a 400 bored 30 and given a 4" stroke.

thanks, can i not stroke the motor with a stroker kit for beter displacement.

If you had an aftermarket block most definitely. I have never clearanced a stock block for a 4" stroke but I imagine you may run into an issue with how much material you take out.. Cam to crank clearance will also be an issue with a stock block. My machinist just switched his 434ci to a raised cam block because his cam was barely clearing and the base circle was already reduced on it.

Adding a 3.750" stroke in a 350 is pretty common and requires minimal block clearance. Ive clearanced a couple of blocks for these and usually the area just below the pan rails get into the way. I have seen a couple where the bottom of the cylinder can get into the way also. This summer I'm building a 4 bolt 350 roller with a 3.875" stroke. That should be fun to clearance!

Putting a stroker kit in a 350 will get you anywhere from 383 to 408 cubic inches. Not that many kits are good for 408 cubes and 600 HP.
Why invest in cubic inches, anyway? A Chinese turbo or 2 from e-bay will get any mild 350 to 600 HP much cheaper than a correctly-built 434. As long as you keep it from ever having any detonation, stock parts can survive, though nearly everyone would do forged pistons to be safe.

Yes you right but I am still a old stock guy. i have seen what you guys have in USA, we have attended the SEMA Show last year. (Awesome) and here in South Africa to find a manifold to support a turbo on a 350 is not even a option - none available. i still battle to get by 383 stroker with all the right groceries to run a 12 second quarter mile. best time was a 13.05. maybe the turbo is another option, i have good contacts after the show to import the manifold. thanks for your comments!!

I purchased a FAST EFI at the Nationals in October last year, when we came back to South Africa i immediately installed the EFI on my 383 Stroker and removed the Holly 750 DP. my problem now is that my car is now a full second slower on the quarter mile. With carb previous best is 13.05 and with the EFI first run 13.72 and then a 14.00. any suggestions or is this proof that a carb is still the best?? i can feel the car struggle half way down the Q/mile.

No, it doesn't prove a carb is better. It proves you don't yet have the EFI dialed in.

Thanks that is what i hoped to hear. i still need to sort out the mixtures.

Are there no big block Chevy motors over there? 600 hp with a 454 would be somewhat easier to achieve and should last longer.

600 horse on a factory 350 block, pre or post '87 is a grenade. Especially if you're boring it to the limit. The only way I'd attempt that is less bore, and a fill in the block. By the time you do that and worry about all the other associated issues you may as well go aftermarket or big block.

K