Stock Head Studs Constantly Loosening

What a wealth of information. I really appreciate everyones' input. I got it firing really well yesterday, running it for ten minutes or so at idle with a brisk fan blowing on the engine. I do not feel as though studs are pulling when I tighten.
They always have a good solid feel, no give. I'm using a torque wrench I trust. It is always a few lbs less than it indicates. Meaning that 20lbs is probably 18, and I am going to 27 on the higher spec bolts, meaning more like 25lbs.
I have a new head gasket here. It is made by Andover-Norton international and has a part # 06.5051.
If I pull the head I will renew all sruds bolts and nuts. I will post as I proceed. Again thanks to all for your input.

robertv said:

What a wealth of information. I really appreciate everyones' input. I got it firing really well yesterday, running it for ten minutes or so at idle with a brisk fan blowing on the engine. I do not feel as though studs are pulling when I tighten.
They always have a good solid feel, no give. I'm using a torque wrench I trust. It is always a few lbs less than it indicates. Meaning that 20lbs is probably 18, and I am going to 27 on the higher spec bolts, meaning more like 25lbs.
I have a new head gasket here. It is made by Andover-Norton international and has a part # 06.5051.
If I pull the head I will renew all sruds bolts and nuts. I will post as I proceed. Again thanks to all for your input.

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Recalibrating a torque wrench is not difficult...just needs a luggage or fish scale and a tape measure...quite a few videos on youtube of the process.

robertv said:

What a wealth of information.

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I've never seen a head need that much retorking, and change that much. Even with a aluminum head gasket I once used in my rookie years of Commando knowledge., Now I don't even see much of change when I retork things and the valve adjustment only changes a thou or so. The 850 flame ring head gaskets are/ were marked TOP to let you which side is up.

Of course, the three head studs that are 3/8 inch are known to pull the threads out of the aluminum head. But the rest of the threads If OEM should be OK

Q) is the valve adjustment changing much after the retork?/ torque? Q) Is the new or old gasket marked TOP?

Valve adjustment is not changing much. After a retorque Very minor or no adjustment necessary. I did install composite head gasket with TOP marked on upper side.

robertv said:

Valve adjustment is not changing much. After a retorque Very minor or no adjustment necessary. I did install composite head gasket with TOP marked on upper side.

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With that information ((without being there) That means to me,
a) the gasket is not compressing much. b) that the threads in the hardware are sloppy, or loosing tork due some physical F--K up. Like the washers are soft or the head surface is not flat and smooth or they are not OEM parts.

Q) if you were to mark the bolts with a marker pen, do they physically turn to loosen? *** Which I have never seen!
Q) do you have all stock OEM Nuts, bolts and threads? The Hex heads should use British wrench sizes and 26 TPI fine threads.

Stock OEM threads and hardware was a strong point in Norton's favor and were very high quality. Surface prep is very important, things need to be flat and smooth to assure leak free performance.

Back in the late 70s my original compositive head gasket blew out in a big way been using copper head gaskets ever since, in near 50 years of riding my Norton my head has only been off 4 times and I am still using all my original head bolts and studs, I can't understand why so many don't use copper head gaskets, put it on and torque up, retorque after 500 miles then forget, been over 15 years since my head has been off and haven't been retorques since the 500 mile retorque, has 40k miles+ on it since and still sealed, haven't even checked the valve adjustment since then as I know when my valves need adjusting by the sound they make or how the bike starts and runs.
Maybe try a copper head gasket.

The engine’s history is unknown so the worst case scenario is that the head has been overheated by a considerable margin - to replace valve seats or guides perhaps - and no longer has the strength to withstand the operating loads from the fasteners. Waisted studs/bolts would improve such a situation.

I appreciate all of the information here. I will mark bolts and see if they turn. I used real Norton washers and hardware that I purchased from a seller in the UK. All used. The head is an RH10. The threads for the exhaust were in bad shape, so I sent the head to James Comstock and he did a beautiful job with the two inserts. A friend who knows Nortons well, thought that the combustion chambers looked so nice, valves proud on seats, I should maybe just run them. The odometer has around 7500 miles on it. Rather than run them, I decided to have my machinist install nos Rowe guides made for the Norton, and used all new Kibblewhite black diamond valves. I have been using the same machinist for over 30 years. He said that the head had a couple of barely noticeable low spots and he was afraid they might not seal well, so he expertly aluminum welded these two small areas and then shaved the whole mating surface down so as to not change chamber CCs. The aluminum in these heads had some porosity as I had expected. It runs very nicely but I have barely 60 miles on it as I dont trust it yet. Between Jim and the machinist, I have $1k in the head so far. Great information from you all. Thankyou.

I have a copper gasket like I used on Triumphs years ago. And the Norton factory composite gasket also. I f I pull the head, I will cerlainly use new hardware like the ones shown. Thanks.

robertv said:

What a wealth of information. I really appreciate everyones' input. I got it firing really well yesterday, running it for ten minutes or so at idle with a brisk fan blowing on the engine. I do not feel as though studs are pulling when I tighten.
They always have a good solid feel, no give. I'm using a torque wrench I trust. It is always a few lbs less than it indicates. Meaning that 20lbs is probably 18, and I am going to 27 on the higher spec bolts, meaning more like 25lbs.
I have a new head gasket here. It is made by Andover-Norton international and has a part # 06.5051.
If I pull the head I will renew all sruds bolts and nuts. I will post as I proceed. Again thanks to all for your input.

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One word of warning
The worst thing you can do to a commando engine is let it idle for too long or too slow
It can turn it into a cam grinding machine ,a fan won't make any difference to this because the oil is fed to the cam and followers by splash
Keep the revs right up if you are going to do that

Instead of running it for 10 minutes with a fan, just hope on it and take it for a run around the block get the oil circulating, as Baz said Norton motors don't like idling too long or being laboured.

Yep - I blip the throttle at traffic lights, not so much for the noise (although it is lovely) but to increase oil flow down the tunnels onto the cam.
That area is the Dominator/Commando's achilles heel!

robs ss said:

Yep - I blip the throttle at traffic lights, not so much for the noise (although it is lovely) but to increase oil flow down the tunnels onto the cam.
That area is the Dominator/Commando's achilles heel!

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I do it for the noise but now I know I’m preserving my cam at the same time; a noisy bike saves lives and the engine

All the experts have weighed in, so now I will have a go.

It is NOT unusual to see the studs into the head put in with helicoils or other inserts to improve the anchor in the alloy. It is also been argued (rather sucessfully in my opinion) that lengthening those studs by a small mount (1/8" or so) will greatly increast the number of threads into the nut and provide better torquing.

How freaked out will you be if you pull a stud out of the head? If no freakage, then ride it. If the idea causes pain, pull it off and put in inserts. Oh yeah, and lengthen the studs while you are at it!

Just one guys opinion.
Russ

Thanks Russ. I decided to just hop on it and ride today. The brand new Amals were very poor for performance., so the Wassels are back on. Perfect idle, and excellent on the road. The ride was only 16 miles, but it started, idled and seemed happy. Higher oil pressure with filter changed. If weather permits, I will ride this weekend.
I live right on a highway in central California. Once you enter, you are committed. Silicon valley drivers do not slow.
I thank everyone for their input. Best regards.

robertv said:

Thanks Russ. I decided to just hop on it and ride today. The brand new Amals were very poor for performance., so the Wassels are back on. Perfect idle, and excellent on the road. The ride was only 16 miles, but it started, idled and seemed happy. Higher oil pressure with filter changed. If weather permits, I will ride this weekend.
I live right on a highway in central California. Once you enter, you are committed. Silicon valley drivers do not slow.
I thank everyone for their input. Best regards.

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Interesting statements.

What Wassel Carbs with what jetting. What Amal carbs with what jetting. The current Wassell carbs are knockoffs of the Amal Premier carbs but still in Zinc vis the aluminum of the current Amal Premier carbs. The Wassel carbs cost a LOT less and work, so I'm not knocking them, but they do not have carbs pre-jetted for Commandos.

Any idea how changing the oil filter (it's on the return side) increased the oil pressure?

robertv said:

Thanks Russ. I decided to just hop on it and ride today. The brand new Amals were very poor for performance., so the Wassels are back on. Perfect idle, and excellent on the road. The ride was only 16 miles, but it started, idled and seemed happy. Higher oil pressure with filter changed. If weather permits, I will ride this weekend.
I live right on a highway in central California. Once you enter, you are committed. Silicon valley drivers do not slow.
I thank everyone for their input. Best regards.

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If the new Amals weren't performing right then you must have them jetted wrong or not tuned right all new carbs must be fitted with the right jets for each bike, needles height setting is also part of tuning, float levels are set right all this done before you even get to take it out.

That is unusual

I'm very surprised that you have no leaks. Then again you might not be pushing the engine much during break in. Leaks under a Norton head I've run across usually don't show up until the engine is run at a good clip for an extended time and gets fully heated up. The highways in California are a good place to open the throttle up and keep it open for a while.

If you do pull the head and decide to use the copper head gasket, spray both sides of the gasket with Permatex copper coat spray a gasket before you install it. Great sealer for a gasket that does not compress. It does make the head a little difficult to remove later, but not impossible.

Many reports of new Amals having swarf in the drilling passages...need to go through them thoroughly, ensuring good cleaner flow through all drillings and do not stop until you get good spray up out the two tiny holes in the carb throat floor.
Also confirm jetting is correct and float is at spec'd height (best checked with clear hose in a drilled out bowl drain cap, check fuel level reaches lip of bowl).

Tornado said:

check fuel level reaches lip of bowl).

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Route the tubing in a vertical position alongside the float chamber, then open the petrol tap and fill the float chamber with fuel. If the fuel level is in the correct range, the fuel will rise in the tube to a point between 0.170" and 0.240" , below the top edge of the float bowl.