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C8 Exhaust Mani. Studs: UNC or NF?
  • Marker345Marker345
    Posts: 90Senior Contributor
    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.
  • Geoff C., N.Z.Geoff C., N.Z.
    Posts: 2,273Platinum Member
    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.
    If you're stuck in a hole, stop digging.
  • mars55
    Posts: 1,060Platinum Member
    The parts manual lists the manifold studs for a stepdown 8 as 3/8-16 x 1-3/8.
  • Marker345Marker345
    Posts: 90Senior Contributor
    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 C., N.Z.Geoff C., N.Z.
    Posts: 2,273Platinum Member
    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.
    If you're stuck in a hole, stop digging.
  • mars55
    Posts: 1,060Platinum Member
    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