Head gasket info needed

Engine, Transmission & Driveline

  1. CanCritter

    CanCritter Senior Member

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    to much schoolin...my head hurts.....found this...refrence….is pretty close to my setup
    reference…..
    quote"The modern equivilent is the Sealed Power cast - they have a compression height of 1.990. If you use inputs of '70 build specs (meaning blueprint deck height, steel head gasket, blueprint chamber size) it will come out around 9.5:1. If you go with reality using the available composite gasket, a deck height of 10.735, and chamber size of 88ccs (which I've found to be potentially smaller than what is in one's hands) it's closer to 8.6:1. Personally I would use a more performance oriented piston. The KB Hypers are great value provided you or your builder can follow directions.
    1970 440 Piston Compression Height?
    Unquote"

    l can live with 9.5.1....anything more would be pushing it with iron heads lm thinkin...ie fuels ect...more readin to do...

    compression ratio...
    1am.....think l have it sorted l think...….
    bore...4.320
    stroke...3.75
    CC 84
    deck clearance...5.64 or 0.078125
    piston compression height 1.991 flat tops
    piston head volume 0.00
    using summits tools..
    Compression Calculator
    leaves me with this
    gasket..
    .020.... 9.37.1
    .039....9.03.1
    .051....8.83
    sooo if l have .079 below deck + .020 gasket gives me basically 100 ?
    ...do l need to raise this..or lower it for proper quench??
    ...is 1.10 am and am completely lost...folks do you know where yer kids are?
    thoughts, corrections,swift kicks welcome....

    man I need to get to bed....so specs tell me l should be 0.035 - 0.045 in. for proper quench so do l use thinner gasket?...
    think l need to recheck my deck height tomorrow..am takeing measurement at side of cylinder...will try to get a readin in center of piston tomorrow...
    ..that's it lm toast....niters folks
    906s on the newyorker was at 9.78.1...am gona have nightmares
     
    Last edited: Jul 11, 2019
  2. twostick

    twostick Senior Member

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    Ideally you would like the piston to be at zero deck with a .039 head gasket. Now you have ideal safe quench, that is to say good quench with no risk of the piston hitting the head.

    If you are planning to use your existing shortblock, that's not possible BUT throwing new pistons into the mix means you can achieve that and tailor a reverse dome or dish in the piston to set your compression ratio exactly where you want it.

    My 493 stroker has a Ross 34cc dish piston that required only .007" to be removed from the deck to square and zero it. With a .039 gasket and 84cc Edelbrock heads it came out to 8.97:1 and performs acceptably on 87 regular on all but the hottest days.

    My preference would be a nice light forged piston because they are available with whatever compression height you need for zero deck but there's nothing wrong with a hypereutectic if you can get a CH that works.

    New pistons and aluminum heads can make any detonation concerns all but vanish if you keep it under 11:1.

    Now just add a 4.25" stroker crank and.... lol

    Kevin
     
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  3. CanCritter

    CanCritter Senior Member

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    after looking at the facts...bottom line is these 516 heads are useless to me unless l change pistons and a bad choice ….
    only win here was l sorted out quench ect...thanx for the help fellas..tis apprieciated
     
  4. Fury440

    Fury440 Old Fart with a dead Fury FCBO Gold Member

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    Paul used Fel-Pro FS7891PT11 - 440 Engine Gasket Kit on my engine, in fact all the various gaskets are Fel-Pro.

    Edit: My heads are 906
     
    Last edited: Jul 11, 2019
  5. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    No I would say they are not useless. The 906 would flow better at higher lift~.500 if you stay mild they will actually work better because they create more turbulence. Not the ideal quench to generate the most velocity, but way better than the dead area of the 906 heads. This is why most aluminum aftermarket heads are a closed chamber design. I would use the fel-pros you will have plenty of compression so losing a tenth or two will not hurt.
    The 516 have small exhaust valves and weird exhaust ports but with manifolds it will matter little unless you want it to spin to 6-7k.
    If they are in good shape ready to bolt on I would use them.
    Do not use any specs in the books to do calculations. Those are the minimums 99% of the time everything is not down or up to those numbers.
     
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  6. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    The 9.78 number on the 906 heads is within the factory margin of error as they were designed to be 9.7 on the standard '70 440. Given a plus or minus .010 milling variance, the heads were right where they should be so you have done the math correctly. I am thinking that the engine should be ok running the .020 gasket if the 9.37-1 number proves accurate. You will be in premium gas territory but given the closed chamber is less like to detonate, you should be ok with maybe some minor timing adjustments.

    Dave
     
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  7. CanCritter

    CanCritter Senior Member

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    frustrated….this gasket issue basically tore down my sails...was gona finish cleanin them early this am and reassemble but awoke not even wanting to look at a bolt or nut...
    Was hopein heads would make difference only to find out lm one step forward two steps back....figured 67-440 and 70-440 no problem..swap heads and get appropriate gaskets and away we go....
    Guess this isn't the case...shoulda just cleaned up the 906s and threw them back on original engine as they have the proper quench(not entirely shure on this point)
    ...look to flow better and and have decent compression at 9.78-1 a fella could work with lm thinkin
    anyway at this point don't know what lm gona do...if the 516s don't have the proper quench am assumeing my bottom end and response will be affected and will be similar to drivein a smog motor and waitin to get up to speed
    like l said ..just plain ole fusterated….guess lll just put the 906s back on and say fuck it
     
  8. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    I am inclined to agree. The 906 has the advantage of the bigger exhaust valves and that head was mated to this '70 engine, so there should not be any unexpected problems. The main upgrade would be to install the hardened valve seats so they do not erode on the unleaded fuels currently available. But you can always wait until the valves go if they look to be in good shape currently and the vehicle is not going to be driven a lot.

    Dave
     
  9. twostick

    twostick Senior Member

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    The 906 will have zero quench of any kind because it is an open chamber. They flow a little more air than the 516 but the 516 will give you a little bump in compression because the chamber will measure about 6cc smaller. If your 516 has had larger valves installed and are fresh and ready to go, I'd put them on. If either set need to be redone, a set of 440Source Stealths are probably your most cost effective solution.

    Kevin
     
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  10. Fury440

    Fury440 Old Fart with a dead Fury FCBO Gold Member

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    Probably don't really matter what you do as long as it's assembled correctly. Lets face it you probably won't beat the heck out of your car anymore than I'll beat on mine. Everything boils down to I'd rather drive it rather than fix it!
     
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  11. fury fan

    fury fan Senior Member

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    FYI - in 67 the 383s had 516 heads, only 440s got the 915s. 350hp 440s have a 1.60 exh valve, the HP 440 got the 1.74.
     
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  12. CanCritter

    CanCritter Senior Member

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    Will probably just clean up the 906s and put them back on and sell the 516s..compression was higher with the 906s and can burn either premium or reg....live and learn
     
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