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Thread: Exhaust stud lock washers

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    Registered User siteunseen's Avatar
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    Default Exhaust stud lock washers

    I've bought the thick "Williams Washer" for the other 5 studs, the ones that do not attach intake and exhaust together- they were with the bolt kit from MSA, are lock washers not required on the exhaust manifold or header?

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    Registered User 5thhorsemann's Avatar
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    I don't have any lock washers on any of the intake oe exhaust studs or bolts. The only lock washers are on the carb to manifold connections. But I will be watching this thread for input.

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    Registered User rocketdog's Avatar
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    No lock washers. Just installed triple webers with new intake manifold and new intake and exhaust gasket and new studs and washers....no lock washers...and none came off the old studs.
    Late 260Z; 2005 Daytona Blue paint; Triple Webers 40DCOE; competition springs w/Tokico HP shocks; Koenig 17x7 Crosshairs w/ Yokohama AVS 215/45 WR 17; Original owner; Show car w/ many awards

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    I just took the ones off my car on the fourth. No lock washers anywhere for the manifolds. I think they would give a bad torque reading if used.
    1977 280z
    1974 260z long gone

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    Registered User Rainman's Avatar
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    The nuts used on the exhaust and intake manifolds are essentially self-locking because they are slightly out of round. This is why you won't find lock washers on them. Hope this helps..


    Nissan Monterey Blue Early '74 260Z
    RLS30-037826
    Complete rotisserie refreshtoration in process

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    I'm going to put 2- M10x1.25 Toyota studs in my cylinder head. 1st bolt under thermostat housing and the last bolt before the firewall. Those were wallerd out big enough that I might not have to drill before the thread tap, exageration but they are threadless about 1/4" going in. I don't think Loctite will be enough on the M8x1.25.

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    Run the proper size drill bit down the hole by hand before you tap the head to be sure you don't brake the tap off in the head. Then open up the hole in the sprung washers to accept the bigger hardware.

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    Registered User siteunseen's Avatar
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    Rainman I've been reading up on "slightly deformed nuts", sounds like the middle of a joke, they say that they work good without lockwashers but only once. Mine are new but someone might find this useful.

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    Registered User 5thhorsemann's Avatar
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    What you are saying is correct, somewhat. Deformed thread lock nuts are one shot, you need to replace the nut and stud or bolt if you remove the nut for service work as the thread deformation causes gauling of the male threads which is the locking mechanism.

    We have a deformed nut, meaning the thread is slightly out of round, but not so bad as to damage the threads when removed. When you reassemble the nut and stud connection it should go together tightly, meaning you can't turn the nut onto the stud without the use of tools. As long as that is the case you can reuse that hardware, if you can fully engage the male and female threads by hand you need to replace both stud and nut because they are worn out.

    Hope this helps.

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    Registered User siteunseen's Avatar
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    Ok I have some more info on exhaust studs from my local Nissan Dealer. I carried one of the studs and nut from MSA, M8x1.25, and asked about a M10x1.25 stud and nut. He had some from their 8 cylinder pick-up, #14064-JG30B STUD $1.98, #01223-N0021 NUT $1.06. that matched length wise and the nuts are truly out of round. You can't tighten them past the last 2 threads in the nut without a socket where as the MSA nut would spin all the way down to the shank on their stud. Parts guy said that those nuts were NOT deformed or out of round because they thread down so easy. He said I should mash them with a vice a little to make them out of round or buy the ones he sales. He has been selling Nissan parts since '85 and said that he's never seen a nut you could tighten all the way with your fingers on a manifold stud. Exactly what 5thHorsemann said. I don't think MSA got the right nuts for me, maybe I'm the only one?
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    Rust Free'ish zKars's Avatar
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    One could just go and buy such apparently "magical" out of round self locking nuts and use them with the stud of your choice avoiding the dealership. I believe they are just run of the mill conical self locking nuts. Their tips are staked, deforming the end of the conical nut. The entire nut is not "out of round". A favorite supplier of mine is Bel Metric. They have them with and without flanges in either the usual 8x1.25 or 10x1.25 if you use a larger stud.

    https://www.belmetric.com/metric-nut...3msv7pldqra8f6
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    Nevermind..
    Last edited by Rainman; 07-11-2012 at 11:06 AM.


    Nissan Monterey Blue Early '74 260Z
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    Complete rotisserie refreshtoration in process

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    Crushing your nuts in a vice is a bad idea!!!

    But seriously, they are deformed and hardened to a specification, too much "crush" and you can damage the stud or head casting, or both. Not enough and the nut could loosen when it heats up. Spend the couple of bucks and get the good parts made to go into an aluminum head.
    Last edited by 5thhorsemann; 07-11-2012 at 01:07 PM.

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    Part number for the M8 deformed nuts. I bought a great header from MSA but the stud kit was wrong.
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    I bought the same stud kit and installed both mnifolds. Hmm time to rethink this now. I may go with lock washers.
    1977 280z
    1974 260z long gone

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    I too just recently installed the MSA manifold bolt kit on my car thinking they were Nissan original parts (a few of the bolts even came sealed in Nissan parts bags). I didn't think much of it until I saw this thread, but the nuts are definitely "normal" nuts as I was able to thread them on by hand. I just had to retorque them this weekend because the manifold was leaking and I suppose I now know the reason. >.<

    I was also disappointed that the MSA manifold bolt kit did not include the thick washers that are used to join the manifolds.
    Another question I have is what is supposed to be used on the far ends of the stock manifold where it has enlarged holes. Just large flat washers?
    Also, I assumed that flat washers went under the small bolts on the exhaust manifold (i.e. the three found in the center) even though none were included with the MSA kit and none were on the car when I removed the manifold. Is this correct?
    Last edited by 8DC; 07-17-2012 at 06:33 AM.

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    While I hate the argument that goes "well I've been doing it that way for years and its worked just fine" due to the obvious "one off" bad statistical implication, but I gotta say, I've never used these fancy self locking nuts on any manifold I've ever had the pleasure to fondle, just regular nuts and split locks, and never ever had one come loose, maybe just need re-torquing after the first run/heat cycle. While it is a good idea to use self locking nuts, and may in fact be the Nissan intended "right" way, I'de hardly suggest that going with regular hardware as being any significant risk. Maybe my engines run with less vibration than some of you-all's ...

    Maybe my opinions are clouded by the fact that taking these self locking nuts on and off requires a wrench the entire way for every single one, and since some of them are hard to get to for an old man, ones that spin on and off easy are my preference. Maybe also the frequency with which I do this to my and other cars also has a bearing on my opinion and the statistical chance that they have enough time in place in vibrate loose....
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    73 240Z HLS30 149331
    69 510 PL510 77603

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    Crumudgeon
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    Quote Originally Posted by zKars View Post
    While I hate the argument that goes "well I've been doing it that way for years and its worked just fine" due to the obvious "one off" bad statistical implication, but I gotta say, I've never used these fancy self locking nuts on any manifold I've ever had the pleasure to fondle, just regular nuts and split locks, and never ever had one come loose, maybe just need re-torquing after the first run/heat cycle....

    Maybe my opinions are clouded by the fact that taking these self locking nuts on and off requires a wrench the entire way for every single one, and since some of them are hard to get to for an old man, ones that spin on and off easy are my preference. Maybe also the frequency with which I do this to my and other cars also has a bearing on my opinion and the statistical chance that they have enough time in place in vibrate loose....
    Exactly! I have never used metal lock nuts on the intake or exhaust of any of my street or racing Datsuns. And I don't install them on customer cars unless the customer specifically asks for them. A regular M8 class 10.9 nut with a new split ring lock washer (every time) and I've never had an exhaust leak caused by the nuts working loose.

  19. #19
    Registered User grantf's Avatar
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    Quote Originally Posted by John Coffey View Post
    Exactly! I have never used metal lock nuts on the intake or exhaust of any of my street or racing Datsuns. And I don't install them on customer cars unless the customer specifically asks for them. A regular M8 class 10.9 nut with a new split ring lock washer (every time) and I've never had an exhaust leak caused by the nuts working loose.
    I think you have answered my question and perhaps saved me another gasket blow out.
    1977 280z
    1974 260z long gone

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