1970 double hump heads

Discussion in 'Engine Topic' started by 1970 gold, Mar 7, 2010.

  1. 1970 gold

    1970 gold Veteran Member

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    Did any of the double hump heads for 1970 have holes for A/C stuff in the front of the heads?
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    IIRC, if they come on a '70, then yes, the heads should be tapped for accesories.
     
  3. 1970 gold

    1970 gold Veteran Member

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    I just bought a set of heads 1970 casting number 3932441 with 2.02/1.64 would these be considered double humped heads?
     
  4. twozs

    twozs Veteran Member

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    double hump heads have to do with the casting mark on the end of the head as the original "double hump" heads were 2.02 by 1.60 valves also know as fulie heads as used on rochester FI engines. right? *edit* Right. [​IMG]
     
    Last edited by a moderator: Mar 7, 2010
  5. yblow

    yblow Member

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    Thats rite some had the accesery mounts some didnt, if it has that big old banana alternator braket than thats a sure sign. Just look for the double humps like in the pic and then bolt holes in the head to mount stuff too. The one in the pic doesnt have acc mounts.
     
  6. 1970 gold

    1970 gold Veteran Member

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    I'm looking to keep true to 1970 and I'm wondering is it worth having a set of 3932441 reworked?? I'm looking for 300/325 HP will these heads get me there???
     
  7. flowjoe

    flowjoe Moderator Staff Member Lifetime Gold Member

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    Same runner design as the "186" casting double humps for '69/'70 but the "441"s have a much larger combustion chamber @ 76.28cc's (whereas "186"s have 64cc chambers). "441"s were only offered from the factory in 1.94/1.5 valve configuration and only on the 250HP 350CID engines. If yours have been opened up to 2.02 valves then I'd double check that it was done properly.

    Will they get you to 300HP? I don't know for sure but a lot depends upon the other components as I'm sure you already know. Are you sticking with other '70 pieces as well?
     
  8. 1970 gold

    1970 gold Veteran Member

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    Yes on the other 1970 parts. Stock intake and Qjet 704202.
     
  9. ZS10

    ZS10 Moderator Staff Member Lifetime Gold Member

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    Even the small valves 1.94/1.5 will support 325hp with a quick bowl blend and clean up. Large valves were 2.02/1.60 but those heads didn't come like that. Might have to use a small dome piston to get the compression up.

    Any real value in these heads is for building a 'year correct' engine, otherwise the big chamber heads aren't worth much at all. Something to consider before putting much $ into them. If they are 1970 car heads, they would have accessory holes, truck heads, maybe not.

    If your intake is a stock iron one, you're going to make it more of a challenge to meet your goal. The alum Z28 intake/Holley would be preferred.

    Personally I'd make it easy and use a vortec, or aluminum heads and just paint them orange.
     
    Last edited: Mar 7, 2010
  10. flowjoe

    flowjoe Moderator Staff Member Lifetime Gold Member

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    Using factory ratings for comparison, the only differences between the 250HP and the 300HP 350's are the intake/carb (2bbl vs 4 bbl) and combustion chamber size in the heads (76cc vs 64cc - which, of course, influenced compression), everything else is the same (cam, pistons, crank, etc) - use a different piston, as ZS10 suggests, and you might get to your goal.
     

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