C8 Exhaust Mani. Studs: UNC or NF?

[Deleted User]
[Deleted User]
edited November -1 in HUDSON
I'd like to replace a couple of exhaust manifold studs on my C8, but since they are broken, I don't know the thread type in the block. Can anyone tell me if they are coarse or fine threads? And also the proper length of stud?

Thanks in advance.

Comments

  • Geoff
    Geoff Senior Contributor
    They are coarse thread. Sorry, don't know the exact length, but this should be a matter of simple measurement. You want to have them so that the nuts are the same height as the thread, so that there is no exposed end of thread to rust and corrode.

    Geoff.
  • mars55
    mars55 Senior Contributor
    The parts manual lists the manifold studs for a stepdown 8 as 3/8-16 x 1-3/8.
  • [Deleted User]
    [Deleted User]
    mars55 wrote:
    The parts manual lists the manifold studs for a stepdown 8 as 3/8-16 x 1-3/8.



    thanks for the response. The only studs locally available are coarse one end, fine the other, so i guess I'll just cut some ATR (all thread rod) to use.
  • Geoff
    Geoff Senior Contributor
    The only problem with that is all-threaded rod ahs no base point to screw down to. You can use fine/coare thread studs no problem. Just make sure you use some anti-sieze past on the fine thread nuts, and some sealant around the coarse end which screws into the block to prevent leakage and rusting. I'm pretty sure the studs go into the water jacket in some positions, so it is best to have a blank section to screw the stud down tight into, otherwise you may have leakage up around the threads if you use threaded rod. Good luck,

    Geoff.
  • mars55
    mars55 Senior Contributor
    If you want go mail order, McMaster-Carr offers a 3/8-16 x 1 1/2 studs for $1.54 each.



    http://www.mcmaster.com/#90281a630/=1z8lgd



    Or unequal threaded for $0.48



    http://www.mcmaster.com/#91563a126/=1z8o1t
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