Thread inserts in the Norton head

comnoz

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Another fascinating surprise, Jim. Thanks for posting. Definitely not what most of us would have expected. I've been using the Timeserts routinely for years on cases, cylinders, and heads on the assumption that they were stronger than helical inserts. Oh well, at least I haven't had any of them fail (yet:rolleyes:). And in some cases, there just isn't enough room for the larger diameter inserts (like with cases bored out for 920 liners). In any case, it looks like the best option is a larger OD insert, if possible, and very coarse OD threads whatever the insert size.

Ken
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.
 
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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.
 

comnoz

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

comnoz

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I have a stock head and a Fullauto head in the oven.
I will pull a couple more studs after lunch. Jim
 
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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.
 

comnoz

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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.
Threadlocker is handy when your taking it apart but at normal operating temperature it is soft and doesn't contribute anything.
 
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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.



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.
 
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Threadlocker is handy when your taking it apart but at normal operating temperature it is soft and doesn't contribute anything.
I was going to reply that heat is the usual method of releasing a fastener that's been inserted with Locktite.
 

comnoz

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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.
 
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APRRSV

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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 get hot for a few thousand miles.
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
 

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The extra length would definitely help as long as there is enough thread on the stud to take advantage of it.
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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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.
 

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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.
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 ?
 

comnoz

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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
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.
 

comnoz

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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.
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.
 
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Threadlocker is handy when your taking it apart but at normal operating temperature it is soft and doesn't contribute anything.
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.
 
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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.





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.




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.

 
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cliffa

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Here I have tested 4 common inserts used in the Norton head. These inserts were all 1/2 inch long. They all fit a 3/8-16 stud.

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.
 

comnoz

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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.
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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