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Discussion Starter #1
Soon I'll be reassembling my '77 T140V engine. I've looked up the torque values as listed in the Haynes book. How do you guys accurately torque these nuts? Do you use a crow-foot torque extension to obtain access with the torque wrench?
 

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I'd treat anything in Haynes to do with OIF with susspicion.

I just do them up "tight"

there was a discussion on here recently about torqueing them
 

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That was me! It turned out I was Re torqueing the head incorrectly. The nuts need to be freed off and then torqued back up. Inner 5/16 in - 16lb/ft All the others 3/8 in - 18lb/ft.

Make sure the threads are in good condition to avoid false readings, do them in the correct order and use a good quality wrench.

The base nuts as Dave said are less of a big deal, just do them tight! Saying that Plewsey doesn't even bother using a torque wrench for the head.
 

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<The nuts need to be freed off and then torqued back up>
If you do that you're doing the job twice Tommy. Your only checking that the nuts haven't loosened for whatever reason, they certainly won't have tightened. In life things only loosen (apart from my waistband!)
 

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Sorry Derry I wasn't being clear. I didn't mean loosen all the nuts at once. Each nut needs to be individually loosened off and then re torqued before moving onto the next one. I definitely found the nuts rotated further this way, something to do with overcoming the initial inertia to get the nut moving.
 

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All to do with friction and stiction, so the physicyists say! - But this was never worked out on a NASA computer, just arrived at by some sort of trial and error at Triumph many years ago, more likely. The important things are that the bolts/nuts are tightened evenly (ie: tighten them in a sensible order, like the diagram in the manual re. head bolts), and to a sensible degree of tightness. There are different torque figures given in different manuals for different tyoes of head gasket: the composite types supposedly need less torque, but need to be torqued to two different figures at close intervals, than the solid copper head gaskets.

Solid copper gaskets are simpler and if nice and soft (new, or newly annealed) will work perfectly. They are probably more reliable too, in that a little error in tightneing is more easily forgiven: if a composite gasket blows, that's that, but you can nip the bolts up again on a copper gasket if you're lucky.
 

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The first thing you need to get right is the large washers on the 3/8" inner head studs.They should be the same diameter (same part) as the washers on outer head bolts.If you have the small washers,they will keep crushing into the head and losing bolt tension (especially the exhaust side).

Fit those studs upside down (turned end down),with a 1/4" ball under each stud.Don't tighten the studs tightly onto the ball (about 1 or 2 ft-lbs).

You should have no trouble torquing/re-torquing the allen head nuts on those studs.I use a piece of allen key fitted into a single-hex socket.

It's normal to just guess on the cylinder base studs,and just make them tight.The nuts on the 3/8" studs should be 35 ft-lbs.I can't find any mention of torque on the outer studs with 5/16" threads.I've seen them broken,and wouldn't use much more than 20 ft-lbs.

You should back off each cylinder head bolt slightly,just enough to move the thread,before you re-torque it.Otherwise,the "stiction" will give a false reading.
 

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Discussion Starter #8
Ok, let me make sure I understand.
The general consensus is to just tighten the base nuts good and tight by feel. The Hynes manual says 20 ft-lbs, but by feel is good enough.
The head should be done with a torque wrench, torqued, untorqued, re-torqued in proper bolt order. The Hynes book says 3/8" outer/inner to 18 lb-ft and the 5/16" centre to 16 lb-ft. There seems to be no disagreement with those values. I'll check out what kind of washers I have under the outer/inner fittings.
I don't understand the 1/4" ball/stud comment, but I'll have to look at the engine again to see if it makes more sense to me then.
 

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If I understand it correctly, a torque wrench can't set the correct torque without "going up to the correct setting", so you back off in order to get the correct click point.

I guess that you could torque an easy to find nut somewhere (even off the point) to 20lbs and get a feel for the feel using your base nut spanner -sort of a control
 

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Sorry forgot to mention the ball bearings. I followed mr pete's advice and dropped a 1/4 ball bearing into the larger stud holes and fitted the studs upside down. Mr Pete is very knowledgable and his explanation that this reduces the chance of distortion of the bores makes sense when you look at how close the studs are to the edge of the bores.

Quick question.....I fitted my copper head gasket and torqued to triumphs figures, I get a little oil weeping after prolonged fastish rides, is it ok to increase the torque by a couple of ft/lbs?
 

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Hi Tommy :)
I can’t speak for anyone else but for me, so in my eyes if you have torqued up the head and it still leaks it is not tight enough
so I would go tighter. If it still leaks there may be distortion on the surfaces that need further examination.
Now I admire Mr Pete and all his great data but, and here is the but all measuring instruments and the stuff you are measuring must be at a set and ambient temperature, over her it’s about 12degC and as I have said before a torque wrench used in winter will give a totally different setting to one used in the summer, so in my eyes this makes a torque wrench unreliable for us lot working in unheated sheds and garages.
 

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When you exceed 18 ft-lbs on the 3/8" bolts,some of those bolts are likely to crush into the head until they have 18 ft-lbs at room temperature.They won't crush into the head until the engine heats up.

The bolt tension increases when the engine is hot,from differential expansion.It's equivalent to about 30 ft-lbs,when the head temperature is 300 F.The head will sometimes get hotter than that.

The aluminium head gets softer as it heats up,and easier to crush.
 

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1/4 inch balls

The first thing you need to get right is the large washers on the 3/8" inner head studs.They should be the same diameter (same part) as the washers on outer head bolts.If you have the small washers,they will keep crushing into the head and losing bolt tension (especially the exhaust side).

Fit those studs upside down (turned end down),with a 1/4" ball under each stud.Don't tighten the studs tightly onto the ball (about 1 or 2 ft-lbs).

You should have no trouble torquing/re-torquing the allen head nuts on those studs.I use a piece of allen key fitted into a single-hex socket.

It's normal to just guess on the cylinder base studs,and just make them tight.The nuts on the 3/8" studs should be 35 ft-lbs.I can't find any mention of torque on the outer studs with 5/16" threads.I've seen them broken,and wouldn't use much more than 20 ft-lbs.

You should back off each cylinder head bolt slightly,just enough to move the thread,before you re-torque it.Otherwise,the "stiction" will give a false reading.
Hi Mr Pete, could you please explain a little more about this practice? Like Aircool, I am about to assemble a 77' T140 engine but just don't quite get the 'ball business'.
 

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As the studs are originally fitted,most of the load on the barrel thread is taken near the cylinder head face where the stud fits tightest.
When you tighten the top nut on the stud,it pulls the barrel face out of shape around the tapped holes.The metal gets pulled upward,so the face isn't flat.The high local load also forces metal sideways,distorting the top of the cylinder.

Upside down with the ball underneath,the shank of the stud doesn't wedge against the barrel face.The load is spread more evenly over the threads in the barrel,instead of being concentrated near the barrel face.

The head gasket seals better on a flat barrel face,and the cylinder stays more round.
 

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Just a note on the 12 point base nuts: You will probably have to thin the outside edge of a 1/2 box-end wrench to get a good tight fit over those nuts. I also cut the open end off a combination wrench to give more turning radius to the wrench.



Scott
 

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1/4 inch balls

As the studs are originally fitted,most of the load on the barrel thread is taken near the cylinder head face where the stud fits tightest.
When you tighten the top nut on the stud,it pulls the barrel face out of shape around the tapped holes.The metal gets pulled upward,so the face isn't flat.The high local load also forces metal sideways,distorting the top of the cylinder.

Upside down with the ball underneath,the shank of the stud doesn't wedge against the barrel face.The load is spread more evenly over the threads in the barrel,instead of being concentrated near the barrel face.

The head gasket seals better on a flat barrel face,and the cylinder stays more round.
Many thanks. Can understand the move now.
 
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