cylinder head torque down

Discussion in 'Norton Commando Classic Motorcycles' started by 3 of them, May 8, 2018.

  1. 3 of them

    3 of them

    Joined:
    Jan 22, 2018
    850 mk 1 composite gasket head torqued on first fitting then 30 miles later most bolts tightend down a little more . after 250 miles gone over them all again , no movement on any except one by the plug hole and that was slight . is the job now done ? head totaly oil tight deep joy
     
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  2. bill

    bill

    Joined:
    Jun 1, 2003
    i would recheck them again in another 1,000 miles also a valve check at ALL retorques
     
  3. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    That’s not my experience, I was frankly alarmed at the movement on mine, so much so that I was starting to think stripped threads / stretching bolts, etc.

    Then, it suddenly stopped.

    I was advised by an old hand to overtorque them initially. I tried this last time and it worked well.

    I can only assume that the factory did similar, otherwise they’d have blown head gasket left right and centre before the first service?!
     
  4. 3 of them

    3 of them

    Joined:
    Jan 22, 2018
    yes sorry i should have mentioned that after tightening i check the tappet clearances, and that when first installing nuts and bolts on the cylinder head i use Graphogen as advised by uncle Norman (White)
     
  5. texasSlick

    texasSlick VIP MEMBER

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    Jan 2, 2013
    I torqued my Atlas head bolts to 25 ft lb one month ago, and left the bike sitting (never started) while I went on the road. Today, I checked the torque. Each of the top bolts required a 1/8 turn to come up to 25 ft lb. The two front nuts on studs, accessed from the top did not require any additional turn. The 3 nuts on studs accessed from the bottom required just a bit of a turn. I am using a 0.035" copper gasket.

    This behavior suggests the gasket "settles in" over time due to clamp pressure alone, without thermal cycling. Thermal cycling no doubt accelerates such compression of the gasket.

    Slick
     
    Last edited: May 9, 2018
  6. robs ss

    robs ss VIP MEMBER

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    Aug 16, 2016
    Slick
    For clarity (and my edification) do you retorque "over the top" of the existing torque or loosen and retorque?

    Rob
     
  7. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    Loosen and retorque is the preferred method, but in this case, I did the "over the top", I felt that was more conclusive something had changed due to time only.

    When I torque a head, or any assembly with a pattern of bolts, I approach final torque value by incrementally torquing the entire pattern to, for example, 80, 90, then 100% of final value. With such a procedure, one incrementally does "over the top" with each successive step. In the procedure cited in reply#5 above, the last step was simply another increment, with the second 100% value separated from the first by a time period of one month.

    To accomplish my objective to observe a time factor, using the loosen and retorque method would have required me to mark the bolts relative to the head, then check angle relative to the mark after retorque. This would be impossible on all bolts except the four next to the spark plugs.

    Slick
     
  8. robs ss

    robs ss VIP MEMBER

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    Aug 16, 2016
    Okay - thanks for the explanation.
    Cheers
    Rob
     
  9. Joe Schlaberdowski

    Joe Schlaberdowski

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    Jan 1, 2017
    I could be wrong, speculate loosening first and then retorqueing is to avoid sticktion that might even get worse after sitting.
     
  10. robs ss

    robs ss VIP MEMBER

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    Aug 16, 2016
    Yep - that was my understanding too Joe.
     
  11. ashman

    ashman

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    Jul 10, 2010
    In all the 43 years of owning my Norton and having the head off a few times in them years as well other Norton motors I have rebuilt for others I torque the head down as the manual says, I torque it down then don't retorque till about 500 miles and don't touch it again unless there is a seepage.
    Reading a lot of threads on here and so many retorque so many times some up to 6 or 7 times in short heat cycles, I could never understand that as doing it the way I have been doing it and have never had any problems at all with leaking head gaskets.
    But everyone have their own ways or thinking but I have always done what my manual recommends, I think people over do the retorquing of head gaskets.

    Ashley
     
  12. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Ash, are you using copper or composite gaskets?

    Maybe composite gaskets have changed in recent years vs back in the day?

    So far I’ve only ever used AN composite gaskets and they have been perfectly leak free. But I’ve been quite shocked to find that it BADLY needs re-torquing WAY before 500 miles.

    Had I not re-torqued, I do not believe mine would have gone 500 miles without some serious leakage.

    With the 920 motor I’m (slowly) building I’ll be using a copper gasket, so will have to learn the knacks all over again !
     
  13. ashman

    ashman

    Joined:
    Jul 10, 2010
    Eddie I have used both over the years but find I have better results using copper head gaskets, the first time using composite I did the normal but after about 10k it blew out big time and had to replace it that was a long time ago and only use copper on all head work from that time.
    I normaly anneal the copper gasket before fitting but the last time I rebuilt my motor I forgot to do and had the head fitted before I remembered, so after 25k on it its still good no leaks and only retorqued once since but I did use some spray on gasket goo at the time.
    But like you say composite gaskets may have improved since I have used them sooooo long ago, but not having any problems with copper head gaskets I just keep using them when needed and yes I have reused a copper gasket again with no problems at all, maybe because I don't over do it with retorquing.

    Ashley
     
  14. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Can’t knock you for using copper Ash, if a copper gasket fails it will usually leak oil badly before it blows completely. A composite gasket is far more likely to blow completely if it fails.

    That’s why most racers use copper.
     
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  15. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    In the technique I cited in reply #7 above, "sticktion" caused by sitting would have worked to hold the final torque setting, not lesson it, as I found it to be. Once the bolt moves, however small, sticktion is no longer a factor., and further arc of the torque wrench is incresng the torgue. Only two nuts were found to be possibly "stuck".

    You raise a good point, however. It may be another month will pass before I can go for crank up. I intend to loosen, then retorque those two nuts today. Then if I let another month pass, I will repeat the entire process, and report back.

    Slick
     
  16. eskasteve

    eskasteve VIP MEMBER

    Joined:
    Sep 24, 2012
    Now that I live in Arizona my Norton riding season is reversed from majority of the country. I put the 73 Norton 850 away in the early summer and then take it out of storage in the early fall. Triple digit temps on a 45 year old air cooled motorcycle is not a happy dance. One thing that I always check before firing it up for the first time is the head torque. I also have a composite gasket and even if none of the head fasteners respond to the torque wrench, at least I have peace of mind. I have about 18,000 miles on the motor since the rebuild and in September 2017 a couple of the nuts needed about a half of a turn. 2016 and 2015 nothing, 2012-13-14 a tad bit. It has never been the same fasteners so I'm thinking that that's a good thing. With an old bike you can never do too much preventative maintenance. The amount of tightening needed after the 2,000 mile mark was so minimal that it was probably not necessary so why did I do it? I only own the Norton and a modern Harley and sometimes I just need to escape to the garage for some bike time. The HD never needs anything and I have the Norton so well sorted out that seldom do I find anything amiss. Checking things in the garage within reach of my mini-fridge is easy, on the side of the road in 100 degree heat just sucks!
     
  17. robs ss

    robs ss VIP MEMBER

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    Aug 16, 2016
    So, if you loosen and retorque, what is the best method?
    Loosen and retorque #1, then #2, etc, etc?
    Or loosen all then go back through the pattern? (seems unlikely)
    I haven't seen a detailed description of this - just "retorque cylinder head after 500 miles" or something similar.
    Cheers
    Rob
     
  18. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Loosen and tighten 1 at a time in normal order of sequence.

    Well, that’s how I do it.
     
  19. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    +1
     
  20. ashman

    ashman

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    Jul 10, 2010
    Thats the way I have always done it as well, by the manual.

    Ashley
     

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