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Thread: Exhaust Nut Torque

  1. #1

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    Exhaust Nut Torque

    Seems to be lots of opinions and ideas out there. The Lyc book I have shows exhaust studs at 40 inch lbs minimum. Does anyone out here know or suggest what the hold down nuts should be torqued to? Thx

  2. #2
    www.SkupTech.com mike mcs repair's Avatar
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    As loose as they will stay on. Or else the flanges bend(with no blow style gaskets). You can sand the flanges flat again a few times before the must be replaced


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    A good place for Nordlock washers.
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  4. #4

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    Interesting. We smaller Cub owners use brass nuts. Over-torquing results in stripping. But Clint has these neat stainless steel flanges he welds on, and it would take way, way more than 40" lbs to make one banana-shaped.

  5. #5
    Steve Pierce's Avatar
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    I have not found a current torque value for the exhaust nuts in any current publication from either Piper or Lycoming. The best thing I have found was in the Jan 1973 Table of Limits that has been superseded which gave a value of 160-180 in-lbs.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
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  6. #6
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by stewartb View Post
    A good place for Nordlock washers.
    and for those who haven't seen them... cool stuff, order some samples and try them...

    I stock them now... no comparison!!!


  7. #7
    www.SkupTech.com mike mcs repair's Avatar
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    Thank goodness. Spruce has simplified the ordering process a great deal! I just spent $150 on lock washers ahead of my engine install. Worth every penny, too.

    If you haven’t tried them? You ought to. They work.
    Last edited by stewartb; 12-24-2019 at 12:02 PM.
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  9. #9

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    Steve is correct. 160-180 inch lbs is what I recommended for many years.
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  10. #10
    RVBottomly's Avatar
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    Quote Originally Posted by stewartb View Post
    Thank goodness. Spruce has simplified the ordering process a great deal! I just spent $150 on lock washers ahead of my engine install. Worth every penny, too.

    If you haven’t tried them? You ought to. They work.
    Timely for me. I've been working on a hardware order for the last week and was trying to figure out which way to go.

    Thanks,
    Vic
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  11. #11

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    My order was quickly filled and shipped from Spruce’s Alaska warehouse. That’s my second order of parts, hardware, and gaskets that have come from the local warehouse recently. Very handy for Alaskans!

  12. #12
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    Quote Originally Posted by bob turner View Post
    Interesting. We smaller Cub owners use brass nuts. Over-torquing results in stripping.
    I use these nuts on the Lycomings as well. They are deeper than the steel Lycoming nut, lock washer and flat washer and they don't rust from the heat. Just run a course thread tap through them, since they are intended for the fine threaded Continentals. They are long enough to cover the entire stud preventing heat and rust erosion of the stud.
    N1PA
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  13. #13
    Steve Pierce's Avatar
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    The STD-1410 factory Lycoming nuts Aircraft Spruce Part# 08-13229 are stainless and I have nut had any rust issues. Their studs are the same and no issues.
    https://www.aircraftspruce.com/catal...clickkey=45483
    Steve Pierce

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  14. #14
    skywagon8a's Avatar
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    I Have seen a lot of rusted studs over the years. Some rusted so much that the nuts will not back off and pull the studs out with them.
    N1PA
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  15. #15
    Steve Pierce's Avatar
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    Same here, that is why I replace with the stainless. No fun doing the Piper Exhaust AD every 50/100 hours
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  16. #16

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    I insisted on the muffler terminating that AD. Nobody was doing it except me, and I hated the job. Never seen a Super Cub without stainless nuts - but have the Heicoil kit ready anyway.

  17. #17
    AkPA/18's Avatar
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    I also recommend the stainless nuts and I also put a little dab of hi temp RTV inside the nut. This coats the stud as you install the nut.
    http://thrustline.com/

    Takeoffs are optional--Landings are mandatory
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  18. #18
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by AkPA/18 View Post
    ..and I also put a little dab of hi temp RTV inside the nut. This coats the stud as you install the nut.
    that's what I heard also from a Cordova guy too....he slathers the studs too.... says it helps...

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