Gasket quality...

Fast Eddie

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So, my T140 sprang a leak from the exhaust rocker box gasket. I wasn’t too worried as I wanted to get inside it soon anyway. One reason being that it’s a bit of an oil burner too.

The leak was due to the fact that the rocker box gaskets were super brittle, they just snapped. In the area of the leak, the gasket had basically crushed and powdered.

The oil burning turned out to be similar, oil was making its way down the rocker box through studs and instead of being sealed by the head gasket, oil was making its way into the combustion chamber. Again, the composite head gasket material around this area was crushed and uneven and in no way in a condition that you‘d expect to seal.

The engine was rebuild when I bought the bike a year and a half ago, the builder knows late Triumphs very well... but... he’s a bit of a Wassell fan. I suspect the gaskets might be Wassell, and being someone who is not a Wassell fan, I suspect this might be the issue.

So... are there any known good or bad gasket suppliers or manufacturers out there?

Harris is as good as we’ve got to OEM, they’d be my normal default choice. Any other suggestions ?
 
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texasSlick

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When I have a tough sealing problem, I usually turn to synthetic cork, and find it stops the leak.

I don't know how T140 rocker box differ from Norton, but my Atlas is on its second set of rocker box and rocker spindle gaskets, and no leaks since I changed from the originals.

Slick
 
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When I have a tough sealing problem, I usually turn to synthetic cork, and find it stops the leak.

I don't know how T140 rocker box differ from Norton, but my Atlas is on its second set of rocker box and rocker spindle gaskets, and no leaks since I changed from the originals.

Slick
I do want to try the ones from @jseng1 next.
 

Fast Eddie

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When I have a tough sealing problem, I usually turn to synthetic cork, and find it stops the leak.

I don't know how T140 rocker box differ from Norton, but my Atlas is on its second set of rocker box and rocker spindle gaskets, and no leaks since I changed from the originals.

Slick
The rocker boxes are separate on a Triumph, bolted to the head, with a gasket between them. It’s not the rocker covers I’m referring to...

The rocker boxes can squirm around a little giving gaskets a hard time, hence they were dowelled on later models.

Copper is often used by tuning types, ditto for the head gasket. The OEM gaskets were those grey faced types and worked well.

Perhaps I’ll end up going copper.
 

texasSlick

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A trick you can try is, after applying the sealer of your choice, to put down a silk thread around the perimeter of the sealing surface, looping the thread around bolt holes. The silk thread prevents the sealer from being squished completely out, and also acts as a "fence" to prevent migration of oil.

PM me your postal address, and I will put 2-3 yards of silk thread in the mail.

Slick
 

Fast Eddie

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If they squirm around then use a stronger glue.
Perhaps squirming was the wrong word? The rocker boxes can move around, especially at high rpm, especially if the valve springs are stronger than stock. It’s the valve springs acting on the rocker boxes that induces the squirming. Glue won’t help.
 

Fast Eddie

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Wire reinforced:
They‘re the ones I was looking for LAB, thanks.

Am still considering copper though...
A trick you can try is, after applying the sealer of your choice, to put down a silk thread around the perimeter of the sealing surface, looping the thread around bolt holes. The silk thread prevents the sealer from being squished completely out, and also acts as a "fence" to prevent migration of oil.

PM me your postal address, and I will put 2-3 yards of silk thread in the mail.

Slick
That’s very kind of you Slick, thanks for the offer. I’m in the U.K. though, postage will cost a lot more than the thread !
 

Fast Eddie

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I use copper with a very faint smear of Victor Reinz grey silicone on both sides, or alternatively Wellseal. No leaks.

Martyn.
 

Fast Eddie

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Thanks Martyn.
Are you talking head gasket and rocker box base gaskets?
The more I think about it, the more I’m inclined towards copper for both.
 
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I was meaning rocker box base but I've used copper for the head also. The Harris supplied flame ring head gaskets are fine also, but do require several re torques.
 

Fast Eddie

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I was meaning rocker box base but I've used copper for the head also. The Harris supplied flame ring head gaskets are fine also, but do require several re torques.
Thanks again Martyn, now, for a bonus point, do you know how thick a Harris head gasket crushes down to?
 
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They start off at 0.065" & crush down to around 0.050" ish (that's British Standard ish) The copper ones I've used have been 0.040" ish.
 
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