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  1. #1
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    Default Understanding compression

    Hi lads,
    just a quick question re : compression.

    say for a 253 hc motor, according to the max Elle ey manual, it's a 9:1 ratio.
    but this is based on using factory head gaskets (believe they are steel shim ones)

    so based on this, say if the heads are shaved minimally, and using aftermarket gaskets (fel pro)
    would the compression remain similar ? (I know they felpro would be thicker, but I'm assuming the shaved heads make up the difference?)

  2. #2
    in the shed buildin shit 3554me's Avatar
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    There are steel shims available on eBay should work well with slightly shaved
    heads
    10.44@128.90 on e85 26x10
    10.34@130.66 on e85 255 radial


  3. #3
    been here .......too long Smitty2's Avatar
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    Quote Originally Posted by 3554me View Post
    There are steel shims available on eBay should work well with slightly shaved
    heads
    'cept they are for 308s and leave a gap around the cylinder
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  4. #4
    in the shed buildin shit 3554me's Avatar
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    Quote Originally Posted by Smitty2 View Post
    'cept they are for 308s and leave a gap around the cylinder
    They say 253

    10.44@128.90 on e85 26x10
    10.34@130.66 on e85 255 radial


  5. #5
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    Boys brings up a good question. Wouldn't all gaskets leave a cylinder gap for possible oversizing of bores?
    Last edited by cemil; 08-07-2018 at 04:21 PM.

  6. #6
    Do you ever leave?
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    Yes but 253 could leave a much bigger gap. Not sure if 253 and 308 head gaskets are different?

  7. #7
    in the shed buildin shit 3554me's Avatar
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    Quote Originally Posted by RedTaxi View Post
    Yes but 253 could leave a much bigger gap. Not sure if 253 and 308 head gaskets are different?
    I think the steel have 2 different part numbers
    10.44@128.90 on e85 26x10
    10.34@130.66 on e85 255 radial


  8. #8
    been here .......too long Smitty2's Avatar
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    Quote Originally Posted by 3554me View Post
    I think the steel have 2 different part numbers
    .. they did (in GMH days) or still do ? (based on pic above)
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