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GM B-Body Forum, 77-79 Caprice/Impala Forum

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GM B-Body Forum, 77-79 Caprice/Impala Forum

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GM B-Body Forum, 77-79 Caprice/Impala Forum

A forum for the owners and enthusiasts of General Motors B-Bodies from 1977-1990, but dedicated to the owners of 1977-1979 Impalas and Caprices. Join up now!


2 posters

    L98 Aluminum heads

    terry cronk
    terry cronk
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    Post  terry cronk Wed Aug 26, 2015 2:29 pm

    I purchased a set of aluminum heads this spring. They came from the 1987-90 Corvettes.

    I was told they had been given a new grind. I proceeded to tear down and found the seals were cracked and not good.

    So I did a valve grind and seat job on the heads. New pressed on seals w/o-ring on the stem.

    I replaced the valve springs with Z28 springs(1.25 outside dia.), keepers and retainers. Good for .525 lift. Some claim .550.

    Before hand I did a little port match to the intake gasket. And a small amount of blending the exhaust port below the valve seats.

    The heads only have 1.94/1.55 valves. A good low rpm, higher torque head.

    All that will go on a basic stock 350 I have. Re-ring, Check the bearings(rod and crank), replace if needed.

    I purchased an Edelbrock intake #2701, Edelbrock #1405(600cfm)carb.

    I will put in the Comps cam #12-238-2. It has a 262/270 duration w/.462-.469 lift. A good 5500 rpm range.

    That will be my install into my 79 Caprice this winter. Along with a rebuilt turbo 350 w/shift kit.

    Right now I have the 3.08 gears. Hoping to go either 3.55 or 3.73 posi.

    Any comments as to the choices?



    terry cronk
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    Post  terry cronk Thu Aug 27, 2015 11:46 am

    I haven't totaled it up as yet.  But I will be weighing the heads, intake and water pump altogether of both the cast iron and the aluminum.

    I am think at least a 70-80# weight reduction on the front end.

    Any guesses?

    I for got to add the shorty headers. Removing the cast iron should be another 8-10# off.
    GM B-Body Forum
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    Post  GM B-Body Forum Fri Aug 28, 2015 11:43 am

    Id go with a 3.73 but thats because thats what im going with, i dont drive the car very much so the 3.73 will just make it a more fun car!
    This is the project i did with mine that i finished earlier this year, the car itself will never be finished since having a project car is never ending. My cam is very similar but im thinking of putting a bigger one in since my application needs it and can handle it. I would have loved to put aluminum heads on but since my bottom end is stock i didnt feel it was worth it to take advantage of the extra compression and power i could get but id have to put new pistons and had the block machined, so i kept it cheap, and so far so happy.
    https://www.gmbbodyforum.com/t281-vortec-head-350-project-build


    Last edited by GM B-Body Forum on Fri Aug 28, 2015 11:51 pm; edited 1 time in total
    GM B-Body Forum
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    Post  GM B-Body Forum Fri Aug 28, 2015 11:50 am

    I know stock smog iron heads weigh in at about 50lbs each fully assembled. heres a post of some weights https://www.gmbbodyforum.com/t307-gen-1-sbc-weights-aluminum-vs-iron#2972
    terry cronk
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    Post  terry cronk Fri Aug 28, 2015 9:20 pm

    Thanks for the weight comparisons.

    The 350 motor I am going to tear down is a lower compression boat motor.

    So the 58cc heads will help the compression. Vortec heads are like 62cc?

    With the B.O.P. axle it should be fine with 3.73.

    I will soon know what is what when the cover comes of.

    Thanks
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    Post  GM B-Body Forum Sat Aug 29, 2015 12:15 am

    Stock vortecs are 64 but i had mine shaved to 62cc and im using steel shim .015" head gaskets, trying to squeeze all the compression i can get, but with your 58cc you can use the standard .041" headgaskets and compression should be real good.

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