T140V 1976 Composite Gasket

[solomon]

By 1980, Meriden had changed the tappet guide blocks and pushrod tubes to eliminate the 70-4752 seals

So can these be fitted to earlier models? Expensive, but not as expensive as a bent head, and the seals sometimes end up leaking anyway.

Anyway, think I will use cooper next time. If a composite slightly crushes, might make things worse on the crush front.

It will take me about 2 weeks to get the new copper gaskets regardless

If trying a new gasket before resorting to sending head off to straighten, I'd torque it to spec, then leave for a day. It's possible the head might slightly settle/ flatten. Then check torque before riding. Then torque again after a short heat cycle. As there are the slight indentations under washers, too, I'd do a few torque checks. I know they aren't considered necessary, but won't harm.

Important to follow the Triumph sequence of torquing each bolt. And do each torquing in sequence and in steps, i.e. don't torque first bolt fully, then the next.

As you are leaking under the four inner bolts, the 20lbs some suggest on these four to counteract the rocker covers pulling might be good.

 

[Rudie]

By 1980, Meriden had changed the tappet guide blocks and pushrod tubes to eliminate the 70-4752 seals.

can these be fitted to earlier models?

Afaik, yes - the cylinder block 71-4005 part number does not change. However, as tappet guide blocks should be an interference fit in the cylinder block, wise to measure both present and replacement tappet guide blocks with a micrometer or at least good quality vernier calipers?

 

[Migsan]

Afaik, yes - the cylinder block 71-4005 part number does not change. However, as tappet guide blocks should be an interference fit in the cylinder block, wise to measure both present and replacement tappet guide blocks with a micrometer or at least good quality vernier calipers?

Thank you @Rudie and @solomon for your awnsers!
So what if I use the cylinder block to try and straighten the head just by torquing gradually the 2 center bolts to 16 foot pounds. Is that something worth a try or it can distort the head even further? Plus should I use heat?
Solomon when you mention heat cycle is it like a 5 minute ride or to warm up the head with a heat gun?
When retorquing I read some people mentioning to slightly relieve the bolts backwards before retightening, does that make any sense???
Cheers

 

[Rudie]

if I use the cylinder block to try and straighten the head just by torquing gradually the 2 center bolts to 16 foot pounds. Is that something worth a try

Try but it may not be successful as the gap is only 0.003 inch - the head may simply 'spring back' when you release the two centre bolts.

There is no one near you with any type of press (where do you live, rural or urban)?

should I use heat?

Not necessary. Plus the cylinder head is designed to radiate heat; if you cannot heat all of a copper a head gasket at the same time, how could you generate enough heat to make any difference to the head casting?

When retorquing I read some people mentioning to slightly relieve the bolts backwards before retightening, does that make any sense?

If you are checking the torque of a fastener that has been torqued to specification already, unscrew the fastener a very small amount only to ensure, when the torque is checked, there is no stiction between male and female threads.

 

[solomon]

So what if I use the cylinder block to try and straighten the head just by torquing gradually the 2 center bolts to 16 foot pounds

ALL the bolts would be tightened a bit following the correct SEQUENCE. Do you have a Haynes manual, it's in there?
So following sequence, tighten each to say 'just' tight, each to 5lbs under, each to 2lbs under, each, STILL FOLLOWING IN SEQUENCE to spec.

It's more hoping the head will then be sufficiently flat, there's no 'trying' involved.

As you say, back off each bolt a fraction each time, then SMOOTHLY torque until wrench clicks.

Is the underside of the cylinder head smooth? No damage? You could post a pic.

 

[solomon]

Solomon when you mention heat cycle is it like a 5 minute ride

Yes, I'd do it until cylinders and head are hot. 5 minutes ride probably good. Let it fully cool before any torquing, always.

 

[Rudie]

ALL the bolts would be tightened

Then the force the bolts on the axis of the bend can exert on the bend is reduced. As @Migsan is trying to remove a bend in the head; only the bolts on the axis of the bend (or either side of the axis if none on the axis) should be tightened.

 

[Rudie]

if I use the cylinder block to try and straighten the head just by torquing gradually the 2 center bolts to 16 foot pounds. Is that something worth a try

it may not be successful as the gap is only 0.003 inch - the head may simply 'spring back' when you release the two centre bolts.

Also, attempting to straighten the head on the block, you should check the top of the block is flat ...

If you must use the cylinder block to straighten the head, another way to consider is:-

. Turn the head upside down and fit it to the block with:-

.. a thin piece of wood between the head and the block, wood parallel with the axis of any bend you are trying to straighten;

.. plus perhaps old gaskets between the wood and the gasket mating surfaces(?);

.. the outer head bolts through the head into the block;

. this way you have constant access to the head's block mating surface as you try to straighten the head.

. Tighten the outer head bolts equally a very small amount at a time while checking the bend in the head you are trying to straighten is reducing.

. Once it appears the head's block mating surface is flat, loosen the outer head bolts and check the head remains flat - it has not "sprung back".

 

[Migsan]

ALL the bolts would be tightened a bit following the correct SEQUENCE. Do you have a Haynes manual, it's in there?
So following sequence, tighten each to say 'just' tight, each to 5lbs under, each to 2lbs under, each, STILL FOLLOWING IN SEQUENCE to spec.

It's more hoping the head will then be sufficiently flat, there's no 'trying' involved.

As you say, back off each bolt a fraction each time, then SMOOTHLY torque until wrench clicks.

Is the underside of the cylinder head smooth? No damage? You could post a pic.

Thank you again @solomon and @Rudie your help! is much apreciated!

I live in a Rural area in Portugal! I can see if there´s a company with a similar press like the one @Rudie described. In regards of the sprung back of the head once the pressing force is removed, won´t that happen using the press as well?

I have the manual and followed the correct sequence when all the tightening and retorquing was done but I didn't unscrew the fasteners when I did the retorque.
I believe the composite gasket was too compressed. Not only part of it was stuck to the top of the cylinder block but the cylinder head got tinny marks from the gasket metal plate.

All the studs from the cylinder block are really strongly stuck and I was never able to remove them from the block.
I will only be back home in 2 weeks due to work. When I return I can confirm if the top of the block is flat as well and post pictures of the cylinder head. I am working in the UK so if need be I can always bring the cylinder head back with me and try to find a more specialized shop.

Cheers!
Miguel

 

[Rudie]

In regards of the sprung back of the head once the pressing force is removed, won´t that happen using the press as well?

If the head springs back when pressure is released, press it a little more - so the gasket mating surface to the cylinder block is a little convex - so, when the pressure is released, the head springs back to flat.

If pressing the head until the mating surface to the block is a little convex, if the head does not spring back to completely flat, turn the head over and press it a little in the opposite direction ... Because the head is a sand casting, it is relatively soft and easily bent. That is why, when straightening a bend, only a little pressure must be applied and the pressure must be released and the head checked frequently.

I live in a Rural area in Portugal

Rural area of England, I used a local agricultural engineer - in my experience in the UK, whatever the area type, businesses that produce something need engineers to fix the machinery they use. However:-

I am working in the UK so if need be I can always bring the cylinder head back with me

... where in the UK are you working?

 

[Migsan]

If the head springs back when pressure is released, press it a little more - so the gasket mating surface to the cylinder block is a little convex - so, when the pressure is released, the head springs back to flat.

If pressing the head until the mating surface to the block is a little convex, if the head does not spring back to completely flat, turn the head over and press it a little in the opposite direction ... Because the head is a sand casting, it is relatively soft and easily bent. That is why, when straightening a bend, only a little pressure must be applied and the pressure must be released and the head checked frequently.


Rural area of England, I used a local agricultural engineer - in my experience in the UK, whatever the area type, businesses that produce something need engineers to fix the machinery they use. However:-

... where in the UK are you working?

Hi Rudie
I see what you mean! That´s why you mentioned to elevate the head with the wood splint in order to make allow it to compress it until it's convex.
I am in Dorset for the time beeing.
Thanks
Miguel

 

[Rudie]

in Dorset

Town you are in or near?

 

[Migsan]

Town you are in or near?

Poole!

 

[Rudie]

In a similar position, I would enter "engineer poole" into the search of the browser I use (Google in my case), it returns around 20 links. Ime, I would avoid the ones with websites featuring CNC machinery, will want too much money. I would telephone a few of the remainder, explain I want to straighten a slightly bent old motorcycle cylinder head casting, on "something like a fly press"; I would expect either one familiar with old motorcycles to know exactly what I mean, or a recommendation of another engineer who will. Avoid any who suggest skimming the head to remove any bend.

 

[solomon]

These hipsters are in Poole
https://www.sbomb.uk/the-speedshopOr another vintage mechanic/builder might 'farm it out ' if not able to do it themselves.

 

[Migsan]

These hipsters are in Poole
https://www.sbomb.uk/the-speedshopOr another vintage mechanic/builder might 'farm it out ' if not able to do it themselves.

Thank you very much @Rudie and @solomon!
I will see what I can do once I get home and decide if it's worth to bring the cylinder head here. I will keep you guys posted!
Really grateful for all your knowledge
Cheers
Miguel

 

[Migsan]

Thank you very much @Rudie and @solomon!
I will see what I can do once I get home and decide if it's worth to bring the cylinder head here. I will keep you guys posted!
Really grateful for all your knowledge
Cheers
Miguel

Hi @Rudie and @solomon
Just give you guys an update! So I used four wooden matches on each side of the cylinder for lift and placed the two central nuts of the cylinder head in place. Torqued them both gradually first to 18 foot/pounds followed by 20, 22 and 24 mesuring in between. Managed to reduce the gap from 0.003 inches to barely fitting the tip of a 0.0015 feeler gauge. Pretty happy with that. tomorrow I will check the crush.
Also warmed up the cooper gasket with the torch by sections and it's looking very soft so I believe it should be enough or does it have to be cherry red hot literally?
Cheers

 

[solomon]

Just give you guys an update! So I used four wooden matches on each side of the cylinder for lift and placed the two central nuts of the cylinder head in place. Torqued them both gradually first to 18 foot/pounds followed by 20, 22 and 24 mesuring in between. Managed to reduce the gap from 0.003 inches to barely fitting the tip of a 0.0015 feeler gauge. Pretty happy with tha

Well done! Brave man! I've read countless posts on bent heads, never read one where someone straightened it themselves.

Cherry red is just before melting point on copper. Dull red is what I understand to be okay. I do it in a poorly lit room, so can see the dull red better.

 

[Migsan]

Well done! Brave man! I've read countless posts on bent heads, never read one where someone straightened it themselves.

Cherry red is just before melting point on copper. Dull red is what I understand to be okay. I do it in a poorly lit room, so can see the dull red better.

So I was trying to check the crush and I am a bit confused. I haven't tried the double gasket @Rudie technique yet. Placed one gasket and finger tighten all the bolts and nuts by order. Can barely fit the tip of a 0.017 feeler gauge.
On the other hand the amount of plays on the tubes is I would say greater than 0.04! Never had a leak from the tubes before! The picture show the tube play with the tube pushed up!
Any thoughts?

 

[solomon]

Rudie might be able to help more. From what you are saying, there is no crush height. The translucent rings come in varying heights. so one possibility is the rings need to be thicker.
Your seals look normal to me.
Are these the same seals as before?

Perhaps you have an extra thick gasket? Copper gaskets come in varying thicknesses. How does this gasket compare to the previous gasket?