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Thread: cosworth bore clearance issues

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    Bodger longy's Avatar

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    cosworth bore clearance issues

    hi all hope you can help

    I'm building my block back up Cosworth 205 block on a 0.5 over bore with mahle pistons so I've had the engine shop look over the block
    and they have said the bore clearance on cylinder 2 3 4 is 4tho but number one is 4.5tho at the bottom and near 5 tho at the top he said this will be fine at that but I would like to hear what you think before I start to build
    get an second opinion first

    thanks Chris

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    Re: cosworth bore clearance issues

    Std or forged pistons? those clearances sound very big for std pistons.

    either way if you had staggered clearances you would normally have the big clearance on no4 because it runs hotter.

    sounds to me like someone been heavy handed with a hone!
    Last edited by Graham; 29-08-2018 at 20:03.

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    Re: cosworth bore clearance issues

    Hi Graham
    There standard pistons not the forged ones

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    Re: cosworth bore clearance issues

    So probably best to find a new block then what clearance would you
    Recommend I need

    Cheers

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    Re: cosworth bore clearance issues

    Quote Originally Posted by longy View Post
    So probably best to find a new block then

    Cheers
    I have a pinto 205 block on standard bores spare if that helps you. Probably needs a rebore but you can do that to suit your pistons.

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    Re: cosworth bore clearance issues

    What about ceramic coating the bores to re-size back to where they should be - and they could be harder wearing?

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    Re: cosworth bore clearance issues

    This is the one i've heard about ........ https://www.poeton.co.uk/apticote-20...r-bore-coating

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    Re: cosworth bore clearance issues

    If the bore clearance is out of spec go to 0.75 oversize?

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    Re: cosworth bore clearance issues

    Quote Originally Posted by wildo105e View Post
    I have a pinto 205 block on standard bores spare if that helps you. Probably needs a rebore but you can do that to suit your pistons.
    I know it’s been answered 100 times before but is the 205 pinto block the same a cosworth 205
    Block
    Thanks

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    Re: cosworth bore clearance issues

    Quote Originally Posted by longy View Post
    I know itís been answered 100 times before but is the 205 pinto block the same a cosworth 205
    Block
    Thanks
    I believe the 205 Cosworth blocks were just the best of the 205 blocks selected, with the closest bore tolerances.
    But of course, once one of those blocks has then been bored oversize that bit goes out of the window.

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    Re: cosworth bore clearance issues

    Quote Originally Posted by rallyrob View Post
    I believe the 205 Cosworth blocks were just the best of the 205 blocks selected, with the closest bore tolerances.
    But of course, once one of those blocks has then been bored oversize that bit goes out of the window.
    That's my understanding

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