hi Pete,
I’m afraid it is a head off job.
regards
Peg.

 

Thank you and of course it would be as the gasket there is fine! Should I go for a copper gasket when replacing or go with OEM please?

 

The gasket to use is personal preference.

Many people on here have used the copper gasket for many thousands of miles, the Copper gaket needs annealing before use, if you remove one carefully it can be used again after annealing to soften it.

My personal preference is the OEM Kilnger type composite gasket on the T140.
These are my reasons:
Up to the 1930’s almost all head gaskets were copper or aluminium. Then the Klinger company in England invented Klingerite composite material, this was good (still is) for ordinary gaskets but not good for retaining high pressure in head gaskets. They then added steel reinforcements to the gaskets in key places, around the bores, oil feeds and water feeds.
The reinforcements did two things, it stabilised the klingerite but also created very high pressure points around the key areas, as the gasket + reinforcement was thicker at these key points. The gaskets were a revolution in engine design, especially with water cooled engines. Just about every vehicle engine built between 1935 and 2010 used them, cars, busses, trucks and motorcycles apart from British ones😱
In 1973 Triumph went from 650cc to 750cc by increasing the bore size from 71mm to 76mm diameter, the undesirable effect of this was that the land between the two cylinder bores was reduced by 5mm. The gaskets had to be narrower at this point, and it caused problems if the head torque was not maintained, a 10th stud was added to the cylinder head near the centre, while improving clamping, it also took away precious gasket material making for some very narrow areas of material.
Top one is T140 750cc bottom one is T120 650cc

Because the gasket was solid the pressure from the head bolts was spread over the whole area of the gasket, the Triumph design exacerbated the problem by having the pushrod tubes pushing upwards just at the point where the gasket was thinnest.
So the gaskets if they was going to fail it would be between the bores.

In 1979 Triumph decided to address the issue on the T140 (earlier on the T160), they fitted the klingerite style gasket.
The reinforcement went around both bores and also between the vulnerable land between the bores. The majority of of the head bolt pressure was now concentrated on these narrow areas, putting the force exactly where it was needed.

back and front of the composite gasket, showing the highly concentrated pressure areas.

Unfortunately, Triumph did not understand that the previous torque routine for the copper gasket was not the same for the composite, so they failed to update their service manuals and failed to train their dealerships in how to install the new gaskets, consequently their were many failures.
The high concentration of force meant the composite gaskets would crush down more than the copper. On initial fitting they need to be re-torqued more times than a copper gasket. If the Triumph dealers had re-torqued the heads at the after run in service their problems would have been reduced.
When I fit a composite gasket, I Torque the head down, run the engine to check oil pressure/return let it cool and re-torque, make an initial 10-50 mile ride let the engine cool and re-torque, at 100-250 miles re-torque again, at run in oil change 500-800 miles re-torque again. At this point the cylinder head bolts/nuts should not move when the correct torque is applied , showing that the gasket is fully seated.
From then on you should not have a problem with the head gasket.
Most failures are due to improper installation by following the Triumph service manuals suggested routine that was devised for copper head gaskets. (Torque on installation and again after 5 miles).

Triumph never gave any instructions on fitting the pushrod tube seals, first make sure you have Viton seals top and bottom, not inferior material that will not withstand the heat. Check the crush down on the seals is around 30 thou (0.75mm.). The late pushrod tube design does not provide adjustment to account for manufacturing tollerances and only different diameter seal selection can alter the amount the seal is crushed, there is an adjustable length pushrod tube on the market that is very high quality. This thread could be useful.
https://www.triumphrat.net/threads/72-t120-pushrod-tubes.1018837/?post_id=2004537699#post-2004537699
If the pushrod tubes are too tight they will relieve pressure off of the head gasket they can also cause the cylinder head to bend, and usually the seals prematurely break up, if the pushrods are too loose, they leak.


The copper gasket needs to be annealed before fitting even if new, I would suggest extra re-torque between 50-100 miles and again after 500-1000 Miles.

It would be prudent to change the tappet block seals and sealing the cylinder base studs that are drilled into the crankcases if you want a leak free engine, but that involves removing the barrels.

Regards
Peg.

 

The gasket to use is personal preference.

Many people on here have used the copper gasket for many thousands of miles, the Copper gaket needs annealing before use, if you remove one carefully it can be used again after annealing to soften it.

My personal preference is the OEM Kilnger type composite gasket on the T140.
These are my reasons:
Up to the 1930’s almost all head gaskets were copper or aluminium. Then the Klinger company in England invented Klingerite composite material, this was good (still is) for ordinary gaskets but not good for retaining high pressure in head gaskets. They then added steel reinforcements to the gaskets in key places, around the bores, oil feeds and water feeds.
The reinforcements did two things, it stabilised the klingerite but also created very high pressure points around the key areas, as the gasket + reinforcement was thicker at these key points. The gaskets were a revolution in engine design, especially with water cooled engines. Just about every vehicle engine built between 1935 and 2010 used them, cars, busses, trucks and motorcycles apart from British ones😱
In 1973 Triumph went from 650cc to 750cc by increasing the bore size from 71mm to 76mm diameter, the undesirable effect of this was that the land between the two cylinder bores was reduced by 5mm. The gaskets had to be narrower at this point, and it caused problems if the head torque was not maintained, a 10th stud was added to the cylinder head near the centre, while improving clamping, it also took away precious gasket material making for some very narrow areas of material.
Top one is T140 750cc bottom one is T120 650cc
View attachment 871060
View attachment 871061

Because the gasket was solid the pressure from the head bolts was spread over the whole area of the gasket, the Triumph design exacerbated the problem by having the pushrod tubes pushing upwards just at the point where the gasket was thinnest.
So the gaskets if they was going to fail it would be between the bores.

In 1979 Triumph decided to address the issue on the T140 (earlier on the T160), they fitted the klingerite style gasket.
The reinforcement went around both bores and also between the vulnerable land between the bores. The majority of of the head bolt pressure was now concentrated on these narrow areas, putting the force exactly where it was needed.

back and front of the composite gasket, showing the highly concentrated pressure areas.

View attachment 871062
View attachment 871063

Unfortunately, Triumph did not understand that the previous torque routine for the copper gasket was not the same for the composite, so they failed to update their service manuals and failed to train their dealerships in how to install the new gaskets, consequently their were many failures.
The high concentration of force meant the composite gaskets would crush down more than the copper. On initial fitting they need to be re-torqued more times than a copper gasket. If the Triumph dealers had re-torqued the heads at the after run in service their problems would have been reduced.
When I fit a composite gasket, I Torque the head down, run the engine to check oil pressure/return let it cool and re-torque, make an initial 10-50 mile ride let the engine cool and re-torque, at 100-250 miles re-torque again, at run in oil change 500-800 miles re-torque again. At this point the cylinder head bolts/nuts should not move when the correct torque is applied , showing that the gasket is fully seated.
From then on you should not have a problem with the head gasket.
Most failures are due to improper installation by following the Triumph service manuals suggested routine that was devised for copper head gaskets. (Torque on installation and again after 5 miles).

Triumph never gave any instructions on fitting the pushrod tube seals, first make sure you have Viton seals top and bottom, not inferior material that will not withstand the heat. Check the crush down on the seals is around 30 thou (0.75mm.). The late pushrod tube design does not provide adjustment to account for manufacturing tollerances and only different diameter seal selection can alter the amount the seal is crushed, there is an adjustable length pushrod tube on the market that is very high quality. This thread could be useful.
https://www.triumphrat.net/threads/72-t120-pushrod-tubes.1018837/?post_id=2004537699#post-2004537699
If the pushrod tubes are too tight they will relieve pressure off of the head gasket they can also cause the cylinder head to bend, and usually the seals prematurely break up, if the pushrods are too loose, they leak.


The copper gasket needs to be annealed before fitting even if new, I would suggest extra re-torque between 50-100 miles and again after 500-1000 Miles.

It would be prudent to change the tappet block seals and sealing the cylinder base studs that are drilled into the crankcases if you want a leak free engine, but that involves removing the barrels.

Regards
Peg.

Hi Peg,

I very much appreciate the information you have given and enjoyed the detail. I come from a world of bikes from the modern era with things like reliability, warranty and electric starters! I have had the T140e for a year now and whilst cosmetically I have succeeded in improving the bikes general appearance, sorted the brakes, forks, shocks and swingarm etc, my engine spannering has been limited thus far to oil changes / consumables and tappet adjustment, but I have also successfully replaced the whole wiring loom as that was a rats nest!

This winter I plan to tackle the push rod leaks, and as you have advised I will be taking a deeper delve into the engine than I thought necessary, so I will follow your tips and advice - thank you very much.

Regards,

Pete.

 

An excellent post as always by Peg, she's got more knowledge on these old things than I'll ever have.

All I'd add is if you do remove the barrels then retorque the barrel retaining nuts when you redo the head as they're known to come loose for some folks.

 

There is (somewhere) a Triumph service bulletin that suggests slightly overtightening the head bolts on initial installation of a composite head gasket in the expectation that the gasket will compress, I did download the bulletin but I cannot find it now.

My T140E had a composite head gasket from new, they have always been good, other than the nuisance of needing several re-torque sessions before they are settle down.

Also note that the composite gasket has to be fitted the right way up, as per the 4th photo in RPW's post.


Found the document; https://britcycle.com/Manuals/CylHeadGskT140.pdf