My Final hallite Head Gasket Advice

hybridracer · Wednesday at 7:00 AM

In these many oil, sorry head gasket, threads I have not seen any mention of hallite, (flame ring composite), head gaskets having a shelf life. This is important because the thermosetting dry adhesives that genuine ones contain do have a limited storage life, after which their effectiveness reduces and they should not be used.

The difficult question to answer is “for how long can they be stored?”, mainly because it’s history prior to you purchasing it is unknown. A good guess would be 2 years.

When purchasing a new one buy from a reliable supplier and check that it has not been in their store for more than about 2 years. Do not buy from “new old stock”. Do not buy to keep as a spare for future use- buy a new one when you actually need it. If you must keep one then store it in a cool, dry and dark place where your other adhesives are kept and throw away after 2 years.

concours · Wednesday at 9:07 AM

hybridracer said:
In these many oil, sorry head gasket, threads I have not seen any mention of hallite, (flame ring composite), head gaskets having a shelf life. This is important because the thermosetting dry adhesives that genuine ones contain do have a limited storage life, after which their effectiveness reduces and they should not be used.

The difficult question to answer is “for how long can they be stored?”, mainly because it’s history prior to you purchasing it is unknown. A good guess would be 2 years.

When purchasing a new one buy from a reliable supplier and check that it has not been in their store for more than about 2 years. Do not buy from “new old stock”. Do not buy to keep as a spare for future use- buy a new one when you actually need it. If you must keep one then store it in a cool, dry and dark place where your other adhesives are kept and throw away after 2 years.

Please, tell us more about the basis of this claim.

I've worked in a plant making head gaskets, (short term vendor) and learned a few things.

Do tell...

Carl H · Wednesday at 4:22 PM

hybridracer said:
In these many oil, sorry head gasket, threads I have not seen any mention of hallite, (flame ring composite), head gaskets having a shelf life. This is important because the thermosetting dry adhesives that genuine ones contain do have a limited storage life, after which their effectiveness reduces and they should not be used.

The difficult question to answer is “for how long can they be stored?”, mainly because it’s history prior to you purchasing it is unknown. A good guess would be 2 years.

When purchasing a new one buy from a reliable supplier and check that it has not been in their store for more than about 2 years. Do not buy from “new old stock”. Do not buy to keep as a spare for future use- buy a new one when you actually need it. If you must keep one then store it in a cool, dry and dark place where your other adhesives are kept and throw away after 2 years.

What is the purpose of the adhesive? is it on one side or both sides of a head gasket?

lcrken · Wednesday at 6:16 PM

Interesting. I'd never thought about that as a problem, and regularly stockpiled original flame ring head gaskets for years. Did the original gaskets from Norton use a TPU from Hallite as dry sealant? From looking at one, I don't see any visible sealant. Was it just part of the composite sandwich material, or a surface coating? Would that have been something like their current Hythane material? Do you know if the current ones from Andover stll use the same sealant? Just curious.

Ken

hybridracer · 2026-07-30T05:45:47-0600

I don’t have specific knowledge of the materials used and little exists on the internet - amazingly when I did a Norton gasket search Google’s AI reply quoted what I had written for Roadholder and copied in the Southern California NOC magazine many moons ago, flattering but not very helpful. Most of my knowledge comes from my time on Westland Helicopters composites sub committee and several years as a composite stress engineer, mainly on Airbus wing components which use pre-preg materials that are formed and cured in autoclaves - comparable to the head gaskets where the adhesive is cured by the engine heat.
The aircraft materials and other thermosetting material I have come across all deteriorate over time in the uncured state, even when correctly stored, so I do not see why our head gaskets should be any different although I am probably somewhat pessimistic with the 2 years shelf life. I don’t know if long term environmental testing has been done to establish lives - ( concours ? ).

Although I did believe that the original gaskets had different adhesives to match the head and barrel I am no longer confident of that or if there are any extra adhesives on the surfaces or it is just the thermosetting adhesive of the gasket matrix also bonding to the head and barrel. I don’t know if materials have changed over the years.
The most important parts of the installation are the surface preparation of the head and barrel and not getting any grease or oil on the gasket.

In the uncured state the gasket is soft and flexible. As it cures with the engine heat it hardens and bonds to the joint head and barrel, the curing process takes time (the hotter the engine the shorter the curing time). A fully cured gasket is hard and stiff. Whilst still curing the gasket can be compressed more under the increased head bolt loads of a hot engine which is why re-torquing is necessary .

Carl H · 2026-07-30T06:06:41-0600

hybridracer said:
I don’t have specific knowledge of the materials used and little exists on the internet - amazingly when I did a Norton gasket search Google’s AI reply quoted what I had written for Roadholder and copied in the Southern California NOC magazine many moons ago, flattering but not very helpful. Most of my knowledge comes from my time on Westland Helicopters composites sub committee and several years as a composite stress engineer, mainly on Airbus wing components which use pre-preg materials that are formed and cured in autoclaves - comparable to the head gaskets where the adhesive is cured by the engine heat.
The aircraft materials and other thermosetting material I have come across all deteriorate over time in the uncured state, even when correctly stored, so I do not see why our head gaskets should be any different although I am probably somewhat pessimistic with the 2 years shelf life. I don’t know if long term environmental testing has been done to establish lives - ( concours ? ).

Although I did believe that the original gaskets had different adhesives to match the head and barrel I am no longer confident of that or if there are any extra adhesives on the surfaces or it is just the thermosetting adhesive of the gasket matrix also bonding to the head and barrel. I don’t know if materials have changed over the years.
The most important parts of the installation are the surface preparation of the head and barrel and not getting any grease or oil on the gasket.

In the uncured state the gasket is soft and flexible. As it cures with the engine heat it hardens and bonds to the joint head and barrel, the curing process takes time (the hotter the engine the shorter the curing time). A fully cured gasket is hard and stiff. Whilst still curing the gasket can be compressed more under the increased head bolt loads of a hot engine which is why re-torquing is necessary .

Years ago, a person asked me about a "flame ring head gasket" he said there was a "glue side and a plain side" and that the glue side bonded to the cast iron cylinder side and that the other side did not bond to allow the aluminum head move some as it expanded and contracted.

That is what he said, If it is true, I have no clue...... But It made me start to put the shiney imprinted side "down" on 750 gaskets,,, the 850 gaskets are already marked top, so that is the side that goes "up". But no matter what you use, proper thread cleaning and proper use of a torque wrench is necessary.

NorCat · 2026-07-30T06:27:08-0600

I have re torque the head gasket 4 times, 50, 200, 200, 500 and only the 5 th time was not needed, so left it there, oficial AN gasquet after a gasket failure due not retorquing.

Both gasquet had the TOP mark so I asumed a treatment layer was in it.

On the first gasquet that failed a Brit Norton user told me to do it the proper way.

Not in the manual nor the instructions gasket packing.

Edfury828 · 2026-07-30T08:04:48-0600

In my work we have limited shelf life for adhesives. All types of tapes, adhesive foam, vel-cro, etc.. My understanding is that all adhesives use solvent. Solvent will always eventually evaporate, compromising the adhesive.

We have dates on everything and throw it away once expired.

o0norton0o · 2026-07-30T08:06:11-0600

I have 2 composite head gaskets for my 750. I've been using one or the other since the 1980's when I first saw them as an option and I had trouble sealing the copper head gaskets. Somewhere in the early 90's I bought the second one to have an extra on hand. Since then I have alternated using them on top end disassembly/reassemblies without any problems. So, one of them is 30+ years old and the other is 40+ years old and both seal fine every time.
I don't generally retorque my head bolts unless I think there's a need for it and maybe I've done a retorque 2 times out of 5 tear downs over the years, but most times the head seals fine on the first torque and stays that way. I never see any blow by staining on the next disassembly. I do surface plate the head and also the barrel surfaces too if the barrels get taken off, just to remove any high spots.
The gasket that I have hanging up in the parts room has the weep hole for the oil to drain port on both sides of the gasket, so it can go either way without blocking the drain hole... I never had an up or down orientation that I can recall..

daveforty · 2026-07-30T08:33:58-0600

My T140 uses a 'flame ring' head gasket as standard fitting. I have found that they need several re-torquings, they even 'settle' overnight such that the head bolts could need re-doing even before the engine is run. Maybe not applicable to Nortons, but Triumph did release a service bulletin (9-79) which suggested overtightening the head bolts by a couple of ft/lbs on initial assembly. The gaskets should be orientated such that the 'bridge' between the cylinders is upwards - at least on the Triumphs, and I have always assembled my Commando that way.

hybridracer · 2026-07-30T10:24:51-0600

o0norton0o said:
I have 2 composite head gaskets for my 750. I've been using one or the other since the 1980's when I first saw them as an option and I had trouble sealing the copper head gaskets. Somewhere in the early 90's I bought the second one to have an extra on hand. Since then I have alternated using them on top end disassembly/reassemblies without any problems. So, one of them is 30+ years old and the other is 40+ years old and both seal fine every time.
I don't generally retorque my head bolts up or down orientation that I can recall..

Re-using these head gaskets is most unusual as they are designed to bond to the head and barrel and removing them damages the gasket. Unless the joint faces had grease, or some other compound to prevent bonding applied to them. I do also recall a suggestion that some gaskets made in the late ‘80s & early ‘90s were made without the surface adhesive and If that is true you could have those.

Question : the gasket you have hanging up, is it hard and stiff like a sheet of tufnol ? If so, it will be acting like a copper or aluminium gasket and won’t, as you report, teed re-torquing

Carl H · 2026-07-30T14:25:46-0600

My bikes only need one check on torque and the valve clearance changes very little. So there is very little crush. But I do lots of prep on the surfaces and threads. The changes of valve clearance can help you understand if it is crush or the bolts and threads that are making things go off kilter.

Triumph in a tech update sheet , recommended using a few extra lbs. or torque when assembling a new top end with a composite head gasket.

I have some new stuff I want to try on my next top end job. I like to try to improve and use new stuff I learn.

o0norton0o · 2026-07-30T16:23:23-0600

hybridracer said:
Re-using these head gaskets is most unusual as they are designed to bond to the head and barrel and removing them damages the gasket. Unless the joint faces had grease, or some other compound to prevent bonding applied to them. I do also recall a suggestion that some gaskets made in the late ‘80s & early ‘90s were made without the surface adhesive and If that is true you could have those.

Question : the gasket you have hanging up, is it hard and stiff like a sheet of tufnol ? If so, it will be acting like a copper or aluminium gasket and won’t, as you report, teed re-torquing

Perhaps the early composite gasket is different from what you discribe because neither of mine ever bonded one side to the barrels or the head and the gasket is hard. As I said it has the drain hole on both sides so I don't think the kind I have had a particular side that needed to face the barrels... It looks like it can go either way. (it's a 750 btw)

hybridracer · 2026-07-30T17:52:58-0600

My '68 Commando had never had the head off from new until about 1980 when I changed the pistons for the solid skirt type. The head gasket was firmly glued to both head and, to a lesser extent, barrel. It took a lot of effort to clean up the faces which is why I remember it. After a couple of weeks use I checked the engine and the head bolts & nuts needed tightening a bit more. I've never had it apart since and it has never given any trouble. It still has the original ball race timing side main bearing although I did fit the latest extra load drive side roller bearing while changing the pistons.

I have come to the conclusion that a lot of what I have written in this thread may be complete bollocks, seeming okay as I wrote it but now I'm not so sure. Like most things one reads on the Inteweb I advise checking, although nothing written here is harmful and it is all good food for thought.

Carl H · 2026-07-30T18:01:36-0600

o0norton0o said:
Perhaps the early composite gasket is different from what you discribe because neither of mine ever bonded one side to the barrels or the head and the gasket is hard. As I said it has the drain hole on both sides so I don't think the kind I have had a particular side that needed to face the barrels... It looks like it can go either way. (it's a 750 btw)

The brand I have seen is Victor Reinz from Andover, I got in gasket kits from a major US parts supplier. From what I know all the gaskets have 2 oil drain holes.

Carl H · 2026-07-30T18:08:14-0600

hybridracer said:
My '68 Commando had never had the head off from new until about 1980 when I changed the pistons for the solid skirt type. The head gasket was firmly glued to both head and, to a lesser extent, barrel. It took a lot of effort to clean up the faces which is why I remember it. After a couple of weeks use I checked the engine and the head bolts & nuts needed tightening a bit more. I've never had it apart since and it has never given any trouble. It still has the original ball race timing side main bearing although I did fit the latest extra load drive side roller bearing while changing the pistons.

I have come to the conclusion that a lot of what I have written in this thread may be complete bollocks, seeming okay as I wrote it but now I'm not so sure. Like most things one reads on the Inteweb I advise checking, although nothing written here is harmful and it is all good food for thought.

I guess Victor Reinz or Cometic would have answers about their products.
From what I have seen it is the timing side ball bearing that fails first.

My Final hallite Head Gasket Advice

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