Why exactly won't these heads fit?

Discussion in 'Engine Topic' started by joel.hunter, Oct 15, 2016.

  1. joel.hunter

    joel.hunter Veteran Member

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    These seem to be a pretty popular head on Summit and I can see why - good spec'd, aluminum heads at $895 (or $1400 Canadian to my door :( ) for the pair. However, it says they only fit SBCs up to 1986 when the changed over the rear main design. I don't understand, though, why it wouldn't fit my '89 (648 cast.) block? Has it got to do with the studs? I presume I could just switch the stud style if so..
    Thanks for any help.

    PS if anyone has a good head recommendation for under $8-900 (USD) I'd love to hear it.

    https://www.summitracing.com/int/parts/mll-h8002k/overview/
     
  2. azkeebler

    azkeebler Veteran Member

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    Im pretty certain the only reason they say this, is due to the different intake on 86 and up. These should bolt up fine to your block as long as your intake matches the heads chosen
     
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  3. hoppin5478

    hoppin5478 Veteran Member Lifetime Gold Member

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    I'm fairly certain they list them like that because GM changed the angle of the intake bolts in 87. The heads will physically work but when you go to bolt up the intake it'll all line up but the bolts go in at the wrong angle. Some people elongate the intake manifold bolt holes to make the manifold work but its best to use the right manifold. When GM made this change they also switched over to center bolt valve covers. I believe those are the issues you would run in to. Someone else may be able to answer the stud question, I'm not sure there but think they will work.
     
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  4. joel.hunter

    joel.hunter Veteran Member

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    Oh ok my intake is drilled for both anyway. Probably get an aftermarket one at some point, too. Awesome, thanks! :)
     
  5. Kamikaze

    Kamikaze Veteran Member Lifetime Gold Member

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    The others are correct that it will fit your 89 blockm the difference is the bolt pattern of the intake.

    87 and later used different angles of the two center intake bolts on both sides. If you are using and early factory or aftermarket intake with the standard intake bolt pattern you will be fine.

    Just make sure your manifold ports line up with the head ports properly and you should have a great combination!
     
  6. John Wright

    John Wright Veteran Member Lifetime Gold Member

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    I used older style heads on my 89 TPI. I had my father-in-law spot face the center bolt holes so my TPI intake would bolt down on those heads.
     

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