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Thread: Manifold Nipple Repair Plan

  1. #1
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    Default Manifold Nipple Repair Plan

    Working on a '37 ULH chopper. Weird carb, stroker, total bastard child.

    This story starts with a manifold issue on a separate OHV bike. A friend silicon-bronzed the nipple into my head. Voila, no leaks. Thanks, buddy!

    Now we come to the flathead. I had a leaky nipple. (One black spark plug, one white one.)

    On this bike, when I brought my friend-o my jug, he was unable to repeat the procedure because A) the step between the nipple insert and cylinder was huge and B) the port is smaller than a Knuck, so the stinger on a TIG torch has to be at a weirder angle and thus farther away, meaning the amps need to be cranked up on the machine, leading to burn-through. When trying to reduce the "step" with a burr, the (very old) nipple got very thin and began to crumble. It had two rivet holes in it, which tells me it leaked at some point so someone took out the rivet, tightened the nipple further, drilled, and re-riveted. Those poor threads.

    My buddy backed the nipple out. (I know this is not the best, but que sera sera. I wasn't there.) It was so loose I doubt there was any damage to be done, happily. The threads are OK-ish, but the nipple feels a bit loose and sloppy until it backs up to the sealing flange, then it feels like it locks up snug. So my plan at this point is to replace this nipple using an exhaust flaring tool as a collet with liberal use of JB Weld on the threads and sealing surfaces.

    Two questions for those of you who are experienced at this:
    1.) Whose nipple do I want? Colony? Carl's? Does it matter?
    2.) Do I need a rivet? I am replacing my seals with the PEEK versions, which drastically lowers the manifold nut torque. So far as I can see, the rivet is to pin the nipple in place so the nuts can be spun off without taking the nipple with it. Since I won't ever approach that torque with the PEEK seals, my instinct is to NOT re-rivet the new nipple and JB weld the existing hole shut. I have major reservations about trying to beat a rivet in place on a jillion-year-old 13-fin jug. Is that a reasonable plan? If not, is the Panhead repair kit appropriate for this application, or no? If not, can someone give me some guidance on how a guy oughta install that rivet without risking the jug? It's a chopper, not a bike on the judging field. I would like to make it as solid and reliable as possible. My thought is if the JB seal doesn't work, I can always go back and rivet it.

    Thanks in advance.
    Last edited by govmule84; 07-23-2019 at 09:13 AM.

  2. #2
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    Govmule84!

    Nipples should always be replaceable, so welding should be avoided anyway.

    Colony's are the only nipples that had a concern that I am aware of.. too large a chamfer on the ID, right where the seal butts against it.

    The purpose of the rivet is to prevent the nipple from backing out when the manifold nuts are loosened.
    Otherwise, you must remove a cylinderhead to get it apart.

    ....Cotten
    PS: JBWeld is time-honored, but it must cure for weeks to resist some modern fuels.
    Last edited by T. Cotten; 07-23-2019 at 09:43 AM.
    AMCA #776
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  3. #3
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    Quote Originally Posted by T. Cotten View Post
    Govmule84!

    Nipples should always be replaceable, so welding should be avoided anyway.

    Colony's are the only nipples that had a concern that I am aware of.. too large a chamfer on the ID, right where the seal butts against it.

    The purpose of the rivet is to prevent the nipple from backing out when the manifold nuts are loosened.
    Otherwise, you must remove a cylinderhead to get it apart.

    ....Cotten
    PS: JBWeld is time-honored, but it must cure for weeks to resist some modern fuels.
    Hey Cotten,

    Thanks for the reply.

    I'm not sure I understand the chamfer issue; I'll be sure to examine the mating of seal and nipple when I get the nipple in hand.

    I understand the purpose of the rivet; my point here is that since the torque I'll be exerting to install the nipple will be so much greater than the torque used to install the sealing ring and nut, is it worth introducing a leak area that won't be serving a function that I can see?

    I am aware JB needs extensive curing time, and I do have time to wait.

    Thank you for the help!

  4. #4
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    Its not about torque, Gov!

    Its about nuts getting sticky, whether from heat cycles or inevitable corrosion.

    Riveting isn't so hard with a tapered head and the right anvil.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  5. #5
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    Quote Originally Posted by T. Cotten View Post
    Its not about torque, Gov!

    Its about nuts getting sticky, whether from heat cycles or inevitable corrosion.

    Riveting isn't so hard with a tapered head and the right anvil.

    ....Cotten
    No doubt, but that involves sealing up a thing, and then drilling a hole in the thing you just worked so hard to seal.

    I understand nuts get sticky, but if I'm at, say, half the torque on the gland nuts as I use on the nipples, seems there'd have to be a lot of rust before a nipple broke free. I understand fully there's no guarantee, what I was hoping was for someone who's used a set PEEK seals to confirm or deny that the rivets still seem necessary. My suspicion is that these nipples took a beating for so many years because those brass ferrules need an unholy amount of torque to crush down and seal.

    Howsabout a rosette weld in the same spot?
    Last edited by govmule84; 07-25-2019 at 09:37 AM.

  6. #6
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    Quote Originally Posted by govmule84 View Post
    No doubt, but that involves sealing up a thing, and then drilling a hole in the thing you just worked so hard to seal.

    I understand nuts get sticky, but if I'm at, say, half the torque on the gland nuts as I use on the nipples, seems there'd have to be a lot of rust before a nipple broke free. I understand fully there's no guarantee, what I was hoping was for someone who's used a set PEEK seals to confirm or deny that the rivets still seem necessary. My suspicion is that these nipples took a beating for so many years because those brass ferrules need an unholy amount of torque to crush down and seal.

    Howsabout a rosette weld in the same spot?
    Gov!

    Please review the discussion at http://virtualindian.org/11techleaktest.html.

    Just ream the rivet hole clean, and lathe-cut a tapered-head rivet to a light press fit.

    A simple cam-action anvil as shown in the discussion will press the taper outward to seal upon the inside, and require only a firm 'upset' smack on the outside, to 'barrel' the shank of the rivet tight, and leave a 'button' that looks authentic.

    ....Cotten
    PS: Beware that PEEK seals must be a tight fit upon the manifold spigots;
    If there are blemishes, they will be impressed into the PEEK, greatly reducing its re-useability.
    Beware also of mass-productions that used brass dimensions, and may also not fit some common modern reproduction nuts.
    Last edited by T. Cotten; 07-25-2019 at 12:00 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  7. #7
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    Quote Originally Posted by T. Cotten View Post
    Gov!

    Please review the discussion at http://virtualindian.org/11techleaktest.html.

    Just ream the rivet hole clean, and lathe-cut a tapered-head rivet to a light press fit.

    A simple cam-action anvil as shown in the discussion will press the taper outward to seal upon the inside, and require only a firm 'upset' smack on the outside, to 'barrel' the shank of the rivet tight, and leave a 'button' that looks authentic.

    ....Cotten
    PS: Beware that PEEK seals must be a tight fit upon the manifold spigots;
    If there are blemishes, they will be impressed into the PEEK, greatly reducing its re-useability.
    Beware also of mass-productions that used brass dimensions, and may also not fit some common modern reproduction nuts.
    Acknowledgements to you, Cotten. I've read your stuff since I started playing with old bikes, including that article at Virtual Indian.

    That said, I'm not the guy to do it the way I'm told "because I said so." I'm also not convinced that that method, which is basically exactly what Harley did, is worth a plug nickel.

    I'm not keen on the idea of drilling a hole in a thing I want to not leak, and I'm also not keen to "smack" a very old and fragile thing.

    Hence my question about a spot weld, or, barring that, the Panhead-style repair kit. This is a chopper. I couldn't give a rip if it looks "wrong." Worst come to worst, I'm gonna put Evo intake flanges on the damn thing and be done with it.

    I'm also not convinced I need anything at all there in terms of sealer. If I use nothing, I lose nothing, except I may have to pull my jug again the next time the intake comes off. If I start using sealant or drilling holes etc., then I have additional problems to contend with down the road. Happily, this can all be checked on the bench. If I get it sealed with no goop and no rivet, at very worst, I am in the same spot I'm in now miles down the road. Best case is that it holds and I have a mark in the W column. My other jug is in about the same shape, but I feel no need to take it apart as... well, it has no symptoms at this point in time!

    I believe when all my parts and materials come in, I'll start fitting some things together and see what I think. I will try to take photos and write down what I find in an effort to help other people with this pain of a problem.
    Last edited by govmule84; 07-25-2019 at 10:32 PM.

  8. #8
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    I've got two knucks that I assembled without rivets and using PEEK seals. So far no problems.

  9. #9
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    Quote Originally Posted by larry View Post
    I've got two knucks that I assembled without rivets and using PEEK seals. So far no problems.
    Good enough for me. What did you do to fill the rivet hole?

  10. #10
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    The nipples were new and not drilled.

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