pre 1974 472 heads on 425ci
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500, 472, 425, 368 Discussion, pre 1974 472 heads on 425ci in Cadillac Engine Technical Discussion; HELLO I hope I ain"t getting hooked on this stuff.however I"ve heard of 425ci.heads going on to 472ci engines, is ...
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    oyoung is offline Cadillac Owners Member
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    pre 1974 472 heads on 425ci

    HELLO I hope I ain"t getting hooked on this stuff.however I"ve heard of 425ci.heads going on to 472ci engines, is it at all possible for pre 1974 472ci heads to be installed on to 425ci.pros&cons please
    Thanks

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    davesdeville's Avatar
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    Re: pre 1974 472 heads on 425ci

    Well, pros would be much better flow and increased compression ratio, just off the top of my head it'd probably be around 10:1. Run the numbers through a calculator though to figure out exact... 425 heads are 96cc and the old 500/472 heads are 76cc.

    Cons might be headgasket issues, you'd have to run 4.3"+ gaskets. I'm freakin tired so there are more than likely things I'm forgetting, someone else should chime in soon.

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    Night Wolf's Avatar
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    Re: pre 1974 472 heads on 425ci

    I know one of the head swapping yeilds a 12.5:1 compression, I think that is 425 heads on a 472/500

    I am not too sure about 475 heads on a 425 though.

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    oyoung is offline Cadillac Owners Member
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    Re: pre 1974 472 heads on 425ci

    What is 4.3"+ gaskets?

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    Re: pre 1974 472 heads on 425ci

    425 heads on a 472 would just do a lot of restricting. They don't raise compression that much. 76 cc heads on an engine that came with 120cc heads will yeild 12.5-13:1

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    oyoung is offline Cadillac Owners Member
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    Re: pre 1974 472 heads on 425ci

    The ? was what happens with pre 1974 472/500 heads installed on 425ci or if at all possible
    THANKS

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    Re: pre 1974 472 heads on 425ci

    Quote Originally Posted by davesdeville
    Well, pros would be much better flow and increased compression ratio, just off the top of my head it'd probably be around 10:1. Run the numbers through a calculator though to figure out exact... 425 heads are 96cc and the old 500/472 heads are 76cc.

    Cons might be headgasket issues, you'd have to run 4.3"+ gaskets. I'm freakin tired so there are more than likely things I'm forgetting, someone else should chime in soon.
    Looks like your question has already been answered.

    4.3 is the bore size

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    oyoung is offline Cadillac Owners Member
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    Re: pre 1974 472 heads on 425ci

    Hello does anyone have any idea what a 425 weights

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