can I bore a olds 260 block to a 350 bore?

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  • John
    Lv 7
    1 month ago

    There may not be enough room in the cylinder sleeves for that much change.

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  • J
    Lv 6
    1 month ago

    Possibly, but why?

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  • Dan
    Lv 4
    1 month ago

    No, and it wouldn't be worth trying. 

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  • 1 month ago

    Nope, most machine shops will not go over "30 over" OEM spec's (.030). Some might go "60 over" (.060) OEM spec's but you run the risk of coolant intrusion into the interior cylinder bore. Sometimes called a "porous block". Porous blocks can be sealed in a shop that has the million dollar machine that does this procedure but the thickness of the cylinder walls has to be at or close to OEM spec's. Meaning, the amount of metal between the water jacket that flows around the cylinders and the inside of the cylinder wall. Cast iron can have small air pockets in it. Just the nature of the beast. 

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  • 1 month ago

    You may be able to get close to your goal with a bore and stroker crank, if anyone even MAKES a stroker kit for that engine. 

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  • 1 month ago

    No way. That's way more than it's possible to bore out the cylinders.

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  • M.
    Lv 7
    1 month ago

    No. 

    260 = 3.500" bore - 3.385" stroke 

    350 = 4.057" bore - 3.385" stroke 

    That means boring .557" larger. 

    That means .2785" removed from the cylinder wall. 

    I don't think the cylinder wall is that thick. 

    -Engine overhaul mechanic and general automotive mechanic since 1972

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  • L.N.
    Lv 7
    1 month ago

    Not a chance. You'll hit the water jackets. You'd have to take the stock bore of 3.5 up to 4.06. No way there is that much extra metal in the block.

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