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Big Block early head info??

Discussion in 'The Garage' started by bablazer73, Dec 3, 2006.

  1. bablazer73

    bablazer73 1/2 ton status

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    I've been looking around for some closed chamber heads for my 454. My brother in law has a set of oval ports. 65-66 396. casting # 3872702. I checked on mortec, but thats all the info they have. I need to know the valve size, so i can figure out If i can even use these heads or if I'm stuck looking for 67 3904390, or 68-69 3931063 heads . It's a low compression engine now. 7.75-1. The early heads closed chamber heads would bump me up to 8.5-1. I would just buy new heads, but they are all 119 cc chambers.
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I want to say the valve sizes are 2.094"/1.72" and those heads are a 109cc chamber which is going to bump your compression up a bunch from 7.75:1, we're talking about a 10cc difference. Those heads also shroud the valves pretty bad and that alone will probably counter act the power gain your looking for.
     
  3. k30bb468

    k30bb468 1/2 ton status Premium Member

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    Couldn't find any info on valve size but it sounds like you want to know the combustion chamber size if you are talking about compression.
    One source states the 3872702 are 96.4 CC & another states 98.4
    I believe they are 98.4CC as I've never seen a set of 96.4CC heads
    also some more info on the 3872702 heads they were used in 66' on
    the 396 L-34 325 HP or L-35 360 HP & 427 L-36 390 HP
    If you are looking for some BBC heads let me know I think I might have a few sets I can part with. :D
    04-05-06 001 (Small).jpg

    04-05-06 001 (Small).jpg
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The "702" castings that i've CCed were all 109cc.
     
  5. bablazer73

    bablazer73 1/2 ton status

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    My books tell me it's a 96.4 CC head. which used with a .039 head gasket will yeild me 8.85-1. with a 109.4 CC, I get 8.09-1, with a 119CC, which what I have on it, I have 7.59-1. The best I can find aftermarket is The Edelbrock performer ovals, milled to a 100CC. They have 2.19 and 1.88 valves. I was trying to find out what valve sizes were on the older heads. I have 1 book and it says 2.065 and 1.720 OR a 1.840 were available on 65-66 396's. I am trying to find out weather the heads my brother in law has are the small or large exaust valves BEFORE i drive down to his place to see them. I might be better off with all the machine work to just buy new! but at 850 each.... well, we all know ...
     
  6. damewood

    damewood Registered Member

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    heads

    i dont' know it all,but ive built several 454's for trucks and blazers and the open chambers seem to make more power almost always.just make up your compression with the pistons.just my 2 cents.
     

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