How do I identify Heads and block
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How do I identify Heads and block

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    Senior Member ClassicBoats's Avatar
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    Default How do I identify Heads and block

    my 77 daycruiser has a hardin marine 454 325hp how do I identify the heads and block? I dont want to buy any parts untill I know what I have to work with.

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    Senior Member Notalent's Avatar
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    Get the casting numbers off the rear of the block and pull a valve cover to get the head casting number....post them here and we will tell you what ya got.
    "Pain is a figment of your Imagination"

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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    Senior Member Notalent's Avatar
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    Quote Originally Posted by SmokinLowriderSS View Post
    Gotta love Mortec! Helped me numerous times
    "Pain is a figment of your Imagination"

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    Senior Member ClassicBoats's Avatar
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    heads have a # of 353049 block #381958 or 991959

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    Senior Member ClassicBoats's Avatar
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    block is a 73-90 2-4 bolt 454
    Heads are 73-84 oval 122cc chamber 255-119 cc ports #353049

    So what does this mean the motor runs strong but im thinking of doing some mods are the heads a good size or do I need something better,
    the heads have dual springs and steel rockers.

    The motor is a 454/ berkley jet, harman logs, stock intake with a holley.
    the boat is a 77, 24' hawaiian daycruiser. I think it has an a or aa impeller
    and it spins 4800 rpm.

    I am wanting a little more out of the hole and a little more top end, any suggestions? Thanks

  9. #7
    River Rat sangervdrive's Avatar
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    I think those heads are the crappy suburban close chamber oval ports. Not much performance wise.
    K and D Racing

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    Quote Originally Posted by ClassicBoats View Post
    block is a 73-90 2-4 bolt 454
    Heads are 73-84 oval 122cc chamber 255-119 cc ports #353049

    So what does this mean the motor runs strong but im thinking of doing some mods are the heads a good size or do I need something better,
    the heads have dual springs and steel rockers.

    The motor is a 454/ berkley jet, harman logs, stock intake with a holley.
    the boat is a 77, 24' hawaiian daycruiser. I think it has an a or aa impeller
    and it spins 4800 rpm.

    I am wanting a little more out of the hole and a little more top end, any suggestions? Thanks
    Heads are open chamber large oval port, some say they're one of the best Chevy produced heads for a jet boat.

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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    Quote Originally Posted by sangervdrive View Post
    I think those heads are the crappy suburban close chamber oval ports. Not much performance wise.
    Yea, they are the good large oval port head, not the peanuts. '049 is/was the replacement for the old '781 casting (identical pretty much).

    Great mid-RPM head, up to arround 6,000RPM (arround 5,000 in stock form)

    If you are considering work on them (mine are being finished up right now),
    The stock valves are usually 2.06/1.72.
    Have them a good stage 1 porting cleanup, They are capable of breathing a lot more than stock.
    resize the valves to 2.19/1.88,
    mine had a leaking exhaust guide so replaced and reduced to 11/32"
    I put in Manley Pro Flow valves
    Got rid of the exhaust valve rotators
    Went to 10* retainers/keepers

    You can port farther than stage 1, BUT, as with all things, the law of diminishing returns gets you. Stage 1 costs least, gets you maybe 80% of what is available. You spend more $$$ for stage 2, get less HP, maybe another 15%. Spend that money AGAIN to get another 5%.

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