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Cylinder head

Discussion in 'The Garage' started by 4X4HIGH, Mar 15, 2007.

  1. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    So what exactly is a GM L98 head? What vehicles did these come on? I'm trying to figure out if the AFR heads i have coming have the exhaust ports raised .100" over my existing heads on my 89 blazer.

    EDIT: May have answered my own question with a little research. It appears that the GM L98 head is the aluminum corvette head. Am i correct?
     
  2. JEBSR

    JEBSR 1/2 ton status

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    They made it in aluminum and cast. They were used in the late 80's vettes, camaro's, and fireturds.
     
  3. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Correct.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    And no port difference with earlier castings. Flow numbers yes, but overall pattern no.

    I *believe* all the L98 heads have the two center bolts vertical, but TPI came out in '85, so I don't know what heads GM used '85-86 before the bolt pattern change.
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Who cares about all that? What I want to know is:

    How many cc's are 781 BBC heads with large valves installed?? :D



    :usaflag:
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    You'll get that answer when i'm able to actually work again. :D
     
  7. Thunder

    Thunder 3/4 ton status

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    L98 (083) Cast iron heads are exactly the same as the 193 TBI heads you (should) have on your Blazer. Same port size same Combustion chamber size. Only diference is the swirl ramp in the intake port on your truck 193 heads.

    As said the Alu L98 heads Came in Vettes. They had 58cc chambers. Also they used the old style intake bolt hole angle and have no EGR.
     
  8. dremu

    dremu Officious Thread Derailer Premium Member

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    Hey, are you doing that too?

    Course, you've got a freakin' 502 under them :eek1: ... mine will be but a measly 454...

    -- A
     
  9. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Actually, his 502 is done, this is for his 496 stroker i'm building.
     
  10. dremu

    dremu Officious Thread Derailer Premium Member

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    Oh, so you finish GREG's motor, what, just 'cause he listens to you :haha:

    (NB for other folks: If I'd listened to Scott and just brought him my motor six months ago like he said I should do, I'd be done by now =))

    496 stroker with 781 heads ... in a K5? That thing's gonna make Burt go "yeeeeeeeeeeeeeehaaaaaww" until the cows come home!

    -- A
     
  11. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    For the record:

    The 1st Gen K5 is getting the 502 (yeah, that should be a YEEEHAAAAW)
    the '72 Burb is getting the 496.....that should give it enough beans to tow the K5 to Moab or Rausch Creek, etc.

    Don't feel too bad about how long things take, the 502 was purchased last summer and was just recently finished. The 496 is based on a core longblock I've been working on buying from IceMan for something like 2 years! :eek1:
     
  12. dremu

    dremu Officious Thread Derailer Premium Member

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    And I coulda read your sig :doah:

    Your sig should, btw, say something like "Greg72: Eradicating smallblocks one truck at a time" =))

    -- A
     
  13. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    Well, this is the same motor I wanna build, a 496... I have a block, and some 781 heads on the way, and was planning on asking 4x4High how much the machine work would run me, funny that this thread should pop up now...

    So, how much to rework the heads for big valves? And what would a ballpark price be for machining the block for a 496 crank. I am slowly accumulating the parts I'll need, I have a complete Mercruiser EFI setup ready to go with it too.
     

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