Are Buick exhaust manifolds mated to the heads, or just machined flat?

Discussion in 'Small Block Tech' started by MrSony, Nov 21, 2018.

  1. MrSony

    MrSony Well-Known Member

    Title says it all.
  2. alec296

    alec296 i need another buick

    Machined flat. You can get those surfaces machined if your having issues
  3. Fox's Den

    Fox's Den 22 years of racing the same 355 Buick motor

    You can get gaskets for this at TA I am sure but at this point I think I would put headers on it. Would be a nice Christmas present!
  4. alec296

    alec296 i need another buick

    Fel pro has manifold gaskets.
    MrSony likes this.
  5. MrSony

    MrSony Well-Known Member

    I was just wondering, picked up a set of non cracked manifolds for cheap. I refuse to pay $500 for headers that probably wont fit my car (85 regal) all that well, and for only a ~30hp gain. I will however, purchase them for my other motor once the heads come out, because I kinda have to. But for now, not in the cards. Manifolds suit me and my 211wrhp just fine. :p
    300sbb_overkill likes this.
  6. MrSony

    MrSony Well-Known Member

    Gaskets or no gaskets then if the manifolds are milled flat?
  7. Mark Demko

    Mark Demko Well-Known Member

    If the manifolds are milled flat again, theres no need for gaskets.
  8. priariecanary

    priariecanary Stacey

    If your new manifolds are not flat, you can try re-flattening them with a file. They warp enough over time to cause exhaust leaks. I filed the manifolds on my BBB 400, put them back on and problem solved. As soon as you hit it a couple times with the file it's easy to see where the problem areas are.
    TrunkMonkey likes this.
  9. 12lives

    12lives Engage! - Jean-Luc Picard

  10. Electra man

    Electra man Older and Slower

    I just had my manifold redone at the machine shop. There was a .010 step where it was leaking at the back of cyl #8. I figured the most needed to clean it up was about .015. Nope between the rusted low spots and the normal warping they had to remove .040" to finally get it completely flat. If I tried doing that with a file it would've taken a week. It only cost me $30 for the one manifold. Bring yours to a reputable machine shop and have them done right. I'm going with a Remflex gasket because the ports on the head have a corrosion also and I didn't pull them to have them cleaned up. I didn't want to do all that work and still have a chug. Unless your doing the port surfaces at the same time as the manifold I would recommend using a gasket.
    BTW that's my thread referenced by 12lives above.
  11. TrunkMonkey

    TrunkMonkey Well-Known Member


    BUICKRAT Torque Rules!

    Factory is cast iron to cast iron, no gasket. Manifolds are machined flat, as is the cylinder head mating surface. If the manifold needs .040 to flat it, you can bet that the head needs a similar amount of machining. If you don't machine the heads, definitely use good thick gaskets. A cast iron to cast iron seal will only work if both mating surfaces are perfect.
  13. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Skip the hassle and machine work and just use remflex gaskets.
    rex362 likes this.

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