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Thread inserts in the Norton head

Discussion in 'Norton Commando Motorcycles (Classic)' started by comnoz, Oct 8, 2019 at 7:16 PM.

  1. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    I knew the Bigsert didn't hold well as I have had to repair several heads that had Bigserts. Then I have to make a reallybigsert, but with coarse threads so they hold.
     
  2. htown16

    htown16 VIP MEMBER

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    Apr 29, 2009
    Do not use a helicoil insert type repair for sparkplugs. They will come back out with the plug and then you are screwed as the hole is then oversize. Jim noted the regular wire type is okay.
     
  3. comnoz

    comnoz VIP MEMBER

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    Dec 10, 2008
    Yes, and the solid spark plug insert is also likely to crack into the valve seat area. It leaves the wall too thin.
     
  4. comnoz

    comnoz VIP MEMBER

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    Dec 10, 2008
    I have a stock head and a Fullauto head in the oven.
    I will pull a couple more studs after lunch. Jim
     
  5. Danno

    Danno

    Joined:
    Feb 7, 2010
    What about using threadlocker on the outer thread of the helicoil? I've put them in a couple of Triumph and BSA heads in the distant past.
     
  6. comnoz

    comnoz VIP MEMBER

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    Dec 10, 2008
    Threadlocker is handy when your taking it apart but at normal operating temperature it is soft and doesn't contribute anything.
     
  7. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    I would like to see you make that test with the helicoil at the exhaust port and the other brands on the intake side where the alum has not been subjected to such high running temps (assuming the ex port area runs hotter). The stud threads near the exhaust seem to be the most failure prone.

    You might want to edit you previous post about the hole breaking through at approx .650" The 850 head below has a hole .830"+ deep and hasn't broken through. A spare 750 I measured has holes that are .750"+ deep.

    [​IMG]

    As far as I know the 3/8 helicoil is available 1/2 and 3/4" lengths. Timeserts are available in 5/8" which is perfect.
     
    Last edited: Oct 9, 2019 at 4:49 PM
  8. SteveMinning

    SteveMinning

    Joined:
    Mar 30, 2008
    I was going to reply that heat is the usual method of releasing a fastener that's been inserted with Locktite.
     
  9. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    I went ahead and pulled the stud in a cracked RH4 I had here. It was a low mileage head and I used a stud with the long threads. Unfortunately the camera battery died so I didn't get a video but the thread pulled at 390 inch lbs.
    I did not go ahead with the Fullauto -it wouldn't be a fair test anyway since the head has not had time on a motor to soften up like they do when they have been hot for a few thousand miles.
     
    Last edited: Oct 9, 2019 at 8:49 PM
  10. APRRSV

    APRRSV VIP MEMBER

    Joined:
    Jun 26, 2016
    Thank you Jim for performing these tests. It is extremely important info, especially the the standard head threads.
    But, as has been asked before, what, in your opinion, does this tell us about routinely torquing the head bolts. Do we need to be ultra-accurate with our torque wrenches?

    Ed
     
  11. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    Absolutely.
    Your latest post regarding the stock 20 TPI ? RH4 thread is interesting and take it by long stud that is one that uses all or near all of the thread available (in the head)

    Does it come back to if a stud with more engagement was available that would be a good investment to folk with stock 20 TPI non pulled threads as a swap over as it looks like it would be in the same game as the inserts ?

    My 850 had one long nut missing when I got it so maybe a good deal of Norton's have those stock studs/fasteners under than over torqued.

    I am glad I did not rush into a sleeve insert and will go Helicoil 3/8-16 with some form of long stud.

    On the exhaust side the two holes could be drilled all the way through so nuts could be attached inside the port.
     
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  12. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    If you put is a 1/2" long helicoil it pulls out at approx 420 lbs torque.
    If you put in a 5/8" long time sert it pulls out at approx 440 lbs torque.
    I'll take the timesert.
     
  13. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    But how much thread engagement are we talking Jim, the stock stud thread length (only 0.450" in the head) or a 0.625 engagement special length stud ?
     
  14. comnoz

    comnoz VIP MEMBER

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    Dec 10, 2008
    Well I would want to avoid overtorqueing the stud nuts and would want the motor to be cold.

    The head I was using for the first tests was a well used head so it probably was fairly soft from the normal annealing that happens with high mileage.

    I do know that some of the lower mileage heads I have checked are harder and would likely hold more torque on the studs.
     
  15. comnoz

    comnoz VIP MEMBER

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    Dec 10, 2008
    With the Fullauto head you can use longer inserts since the exhaust port floors are raised. There is plenty of room for a 3/4 in long insert placed a couple threads deep in the hole. Then if you have at least 3/4 inch of thread on the stud you will be in great shape.

    The standard head [non-Combat] has about .650 thread. Neither stock head stud uses all the available thread. The long factory stud is on the left. The shorter factory stud is on the right. There isn't a big difference.
    P1030053.JPG

    Studs with more thread would be a plus for any head.
     
  16. gortnipper

    gortnipper VIP MEMBER

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    Nov 11, 2013
    What length are the ARP studs?
     
  17. Danno

    Danno

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    Feb 7, 2010
    So it should help keep the helicoil in place when cold-pulling the plugs. For hot plug chops, not so much. Maybe chase the inner threads with a tap after the coil is in and the threadlocker has a chance to dry just to make sure you don't threadlock the plug to the helicoil.
     
  18. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    Time Warp - with a helicoil you only pull on the heli coils that the stud threads engage (it is not solid - it is a spring). But with a timesert you pull on the entire timesert even if your stud is not bottomed in the timesert. But of course the longer the stud threads the better and with a helicoil or timesert you can convert to US threads and better studs.

    Note the .562" length helicoil is too short to engage all the threads of a longer stud for more strength. But the .620" length timesert can engage a stud with longer threads.
    [​IMG]




    The alum Maney cylinders have more distance between the head and the nut that screws on the stud - so the studs can be longer and there is plenty of stud thread engagement with a .620" long insert.
    [​IMG]



    The helicoil is stronger than the same length of a stardard timesert because the helicoil is a larger OD. The timesert is a tighter package with a smaller OD which means you don't have to remove as much aluminum - this leaves more material if there is a "next time". And with a timesert you have the option of a "next time" because you can get a "bigsert" that fits the same stud but uses a larger diameter OD for the timesert - an even stronger setup.

    [​IMG]
     
    Last edited: Oct 11, 2019 at 10:20 AM
  19. cliffa

    cliffa

    Joined:
    May 26, 2013
    Oh Boy, a Thread Thread, this is great !!

    Jim, yet again you deserve thanks and applause by all us Nortoneers for your efforts.

    Can I make a request please. If you have time and another head available would it be possible to do exactly the same test but include one of your inserts, however this time with a large diameter spacer tube without the cutaway and the same size hole as a barrel (jug)?

    My prediction would be:

    Clear Winner - Your insert
    2 - Timesert bigsert
    3 - Standard Timesert (but only if the end flange is wider than the hole in the spacer)
    4 - Helicoil


    I also found this test on YouTube, which although has some anomalies is very interesting..



    Cheers,

    cliffa.
     
  20. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Without the cutaway in the bottom of the spacer the insert would simply pull up to the spacer and stop.
    Then you could get a very high torque reading but it would no longer be holding the head.

    I have seen that happen on the engine, the stud nut torques fine but the head gasket blows because the thread in the head is actually stripped.
     

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