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Hi All, I've just had a +20 rebore with new valve guides done on my
'78 TR7RV and have reassembled using a composite head gasket. Was copper before.
After 2 short runs all seems well but I've had to retorque head after the engine cools by at least 1/2 turn especially inner bolts (not much more than finger tight) and reset tappets each time. I'm concerned how much pressure this could be putting on pushrod tube seals and that much more tightening may lead to leaks.
How many times will this have to be repeated until head "settles"??
I'd be grateful for others experiences/opinions...
Cheers,
Richard
 

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I've heard some ex-race engine builders complain about copper head gaskets saying that they mean a lifetime of head re-torquing ... Evidently, the composite gaskets only require re-torque during the run-in phase.
 

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sounds normal, you will need two or three tightening sessions before it settles down. I have always used composite head gaskets and found them to be perfectly good once it has settled down.
 

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10 stud head ramblings

After enough copper head gasket concerns, I decided a composite one was the way to go.
Research through this forum gave some encouraging pointers.
Service bulletin 9/79 instructs as follows:-
Metal bridge surface uppermost to cylinder head.
Initially cold torque 5/16 studs to 18 ft-lbs and all 3/8 studs to 22 ft-lbs, in the correct sequence.
Run the engine and allow to fully cool.
Retorque 5/16 studs to 16 ft-lbs and all 3/8 studs to 18 ft-lbs, again in the correct sequence.
Reset valve clearances and after 500 miles, retorque to same 16 and 18 figures.
I got the service bulletin info from a link within this forum, but can't relocate it.
I followed the spirit of these instructions when I reassembled my T140 head, but with extra, maybe superfluous operations.
1) I lapped the head and barrel on a surface plate.
2) I lightly greased the gasket faces.
3) I ensured the new studs and nuts were dry, but not degreased.
4) I ensured the tapped holes in the barrel were dry, but not degreased as it is cast iron and self-lubing anyway.
5) I torqued to the figures above and then ran it, I retorqued the following day. I did this again, ran for 50 miles, retorqued, ran another 100 miles, retorqued again. Each time I undid each fastener 1/2 turn and with one slow swing torqued it. In all cases the retaining friction under the head of the external 3/8 bolts was in excess of what was required to just tighten it, so retorquing without undoing would have yielded no extra clamping force. The fasteners moved about 30deg each retorquing.
I'll redo the head again at 500 miles and leave alone if all OK.
I'm not necessarily recommending this, but am content to do it. The service bulletin would have been prepared with the practicalities of achieving cost-effective customer satisfaction.
If you read about torquing fasteners, they're always stated dry, then with reducing factors such as type of material/finish/substrate/lubrication etc. So dry and not degreased was my starting point.
After the engine is run, the inner 3/8 studs should be lubricated, so a reduction may be required here, but I monitored the angular rotation compared to the outer 3/8 bolts to be assured the clamping force was consistent.
When you really think about it the only way to do it is from dry every time, but that means removal of the rocker boxes.....where do you stop?
Sorry to be verbose in this, but I don't have the Plewsy kit expertise!

Good luck
RC
 

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Sorry guys but that has to be the most complicated in-depth over-the-top method i've ever heard of for putting on a damn head gasket!
If Triumph had insisted their mechanics adhered to that, each service would have cost about 1000 pounds.

The thing you missed was composite gaskets do not transmit heat as well as copper, therfore the head will tend to distort more at the front its unable to tranfer as nuch heat into the barrel.
I agree that you shouldn't just do it up 'till your elbow clicks!
But 25 on the 3/8 and 20 on the 5/16 is all you need. Run it for a week or so then do it again. All ok.

With the previous method the threads will wear out before the bike.
 

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use the one you you like better aint no right or wrong answer.

me I be likin the copper cause I'm CHEAP and can anneal the copper one

the cowboy is correct re the 9/79 bulletin. the shop I worked at when these things were new one mechanic liked the copper one liked the 'new' Klinger style.

jus my pinion

K
 

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Hi All, I would agree with Kadutx, there's no right or wrong answer.
It's all down to personal preference, Triumph changed to the composite gasket in 78 on the T140V, however I remember reading an article in "Classic Bike" where they interviewed a T140 specialist, he preferred to use the copper gasket, however he annealed them twice before fitting them.
I'll try and find the article and scan it so you can al have a look.
Personally I like copper because I'm a cheapskate and I can reuse it :)

Webby
 

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Copper for me. I have a '79' T140 head that is going to have to be decked a few thousanths before I can use it. I think it was run loose with a composite headgasket. There is a ring where the fire ring of the gasket would have been that is erroded away.
 

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Discussion Starter #9
thanks to all who replied... good news is after retorqueing 3 times gasket seems to have settled..rings seem to have bedded in...and there seems to be no leaks or smoke... and I seem to be smiling!! :)
 

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All the hashing and re-hashing of dry versus lubed threads for torquing, thoroughly cleaned vs not degreased or what have you...

I just use clean hardware and parts, new copper head gasket with a light smear of copper-coat sealer, and loctite on the headbolts. (how one can use dry threads and loctite at the same time is beyond me)

I retorque WHILE HOT, once, after a half tank of gas (more or less) and I'm all done.

I have never had a failure on a 650 (over 20 top ends by now).

Curiously, I did my first client restoation on a 500 and it developed a leak straight away. Upon removal and re-inspection, I noticed the "original" head bolts didn't look like the ones in the parts book, so I ordered a new set. Sure enough, the "originals" were at least 1/4" shorter than the proper spec bits. Nipped everything up again and all's been well in that department.

"To each his own" or "whatever works for you".
 
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