Probably The Best Ever Mod On A T140

If you have a T140 and are fettling with it. Why wouldn't you? They need a good fettle now and again. You really need to sort these.



These are the inner four head bolt washers (the small ones) and the larger diameter replacements. Have a close look, you can see how the original smaller washers are deformed.

 

This is what happens;

One has a dig into the engine due to some problem or other and bolts up head bolts to required torque. On the head bolts it seems quite low and is different depending on whether it's the outer or inner bolts.

The bolts then require a re-torque a few miles later. Out come the spanners and large allen keys (for the centre bolts 'cause that's what they are). The bolts seem very loose, indeed, it feels like they could be finger tight only. We are now a bit concerned with the torque on the head.

So, redo to torque setting. Although not many people can do the torque on the allen key fittings. Now we are a bit obsessed with the head bolts and may tighten just a bit over.

Head heats up, bolts are a bit over tightened but tighten even more due to expansion. A bit too much pressure for the aluminium head. This can cause the washers under the allen key socket nut to press into the head:



This head has been damaged both by the inner and outer bolts.

 

Once the head bolts have compressed the poor old head then the head actually gets loose - or owners think the bolts need to be tightened up a bit more. This then leads to more compression and loosening and eventually a head gasket fail



The centre of the gasket is also failing



As can be seen by the carbon contaminated oil on the bottom of the centre bolts

 

If the damage isn't too bad you can get your friendly milling machine operator to help out or, if you can find one, get another head like this one.



This second hand head hasn't been abused by the previous owner and now has nice new shiny valves, springs and guides.

 

To stop this mildly irritating problem of an ever enlarging oil spill and ever increasing torques onto the head bolts, buy the 4 nice new inner bolt larger diameter washers. The larger washers will spread the load from the bolts so the head isn't effected by the heat cycle or unknown torques put onto the inner allen key bolts.



Buy or make a tool that can be torqued to the correct load for these head bolts. Cut a bit of correct size allen bolt and stick it into a socket so the torque wrench can be used, jeez, how simple is that.

Those clever dicks in ye olde Triumph design sheds knew a lot more than anyone else on how these machines work. So stick to the torque settings that are recommended by them in the maintenance manuals.

In the mean time, if you have a T140, go buy 4 washers. And, remember, that black soot comes right off with a wire brush.

 

Just as a side note. Remember that the push rod tubes seals need to be correct. If the thicker seals are used it may not be possible to get the head gasket to seal and the head may even be distorted. Check the push rod tube crush before anything is tightened up. Again, go look it up in the manual for your model and use the correct sized seals. Oh what fun

 

Due to the hundreds and hundreds of requests. I'm carrying on with the very interesting (you didn't want to do that) photos from the garage.
Here's the evidence. The inner and outer head bolt washers. They are forever imprinted onto the old cylinder head.

 

As mentioned above it is important to ensure the oil seals on and under the push rod tubes are compressed to stop oil leaks. T140s have additional oil seals internally to the tubes and a steel ring (wedding band) around the bottom compressed seal on the tappet block so that it doesn't squish out. I'm sure that's clear enough to understand.
The bottom oil seals come in different thicknesses:



The correct thickness must be chosen to allow the cylinder head, once bolted down, to compress the oil seal enough to stop oil leaks. BUT the seal must also be thin enough to allow the bolted down cylinder head to compress the head gasket. If the seals are too thick then the cylinder head will not compress the head gasket and it will blow. As the push rod tubes are centrally placed, trying to force the head gasket to seal will distort the aluminium cylinder head. It's a problem ain't it?
Lucky for us, there's a solution, phew.

 

It's a bit of jiggery pokery but the correct oil seals are chosen so that once the push rod tubes are in place, head gasket on and the cylinder head is placed on the push rod tubes, there's a specified gap that can be measured between the head gasket and the cylinder head. This is called the crush. Cor. It can be anything from 40 to 60 thou. That's 0.040 to 0.060 inches.
We've all got feeler gauges (if you haven't then nick some off of someone who has). Measure the gap and play around with the seal thicknesses until it all works. Goody gumdrops.



Measure at the centre of the cylinder head, next to the push rod tubes, as the cylinder head may be rocking if you just measure at the outside edge.

 

Now, bolting down the head. This needs to be done slowly and accurately. Here's the T140 quoted torques:



And here's the sequence:



For info, here's the T120 workshop manual torques. Note what it says at the bottom:



The torques were changed for a reason.

 

Here's the cut off piece of old allen key to allow the torque wrench to be used.



The torques are quite low so start by doing the bolts up in sequence with fingers only. Then torque in sequence up to 10lbft. Then up to 13lbft. Then up to 16lbft.
That's the smaller diameter centre bolts done. Then still in sequence torque the larger diameter bolts to 18lbft.
16 to 18 lbft takes about a twentieth of a turn. See how easy it would be to over torque. Take your time.



All the nice new washers are in place and everything is all bolted down. Luvly. Now the rockers can go on.

 

Still waiting for an order of quality rocker box oil seals but forgot I had some copper ones, hooray, we'll use those.



The copper ones didn't fit perfectly around the new washers, so they need to be tweeked without bending them. Mark up the problem areas and file them down while in a vice.



Once they fit nicely, with all the bolt holes lining up



Spray them with the copper sticky stuff



Allow the solvent to evaporate, install the push rods with a blob of grease on each end making sure they are engaged with the tappets (by slowly turning over the engine and watching the push rods rise and fall) and bung the gaskets on. (Make sure the push rods fit through the holes in the gasket while you are making adjustments to the copper gaskets.)

 

Then pop on the rocker boxes after slackening off the adjusters and levelling the push rods by turning over the engine slowly by hand with the kick start.



Once the box is on then tighten up the adjusters by finger and turn the engine over slowly making sure the rockers are pushing the valves in and out. Then do the same for the remaining rocker box.



Pop the sparkplugs in by hand to keep any little bits and bobs out. Time for tea. Over.

 

Set the tappet adjusters and rocker oil feed wiv nice new washers



Fiddle about to bolt on the engine stay but leave the cover off to allow the bolt to feed through



Clean up the scruffy zorsts





Refit zorsts (which is a right arse as everything needs to be loosely fitted together and positioned to slowly wobble in from each side) with high temp silicone. Then the megadrone on and on mufflers.



Over.....

 

The new stash of proper rocker box gaskets came so whipped out the copper ones and used the new ones instead. The copper ones leaked badly (I wondered why I had them stashed away rather than having used them) so mashed them up and chucked in the metal scrap bin. They wont get used again - ha ha, that'll teach you ya rubbish coppery bollox. Blimey.



Here's a rob from another site (thank you, other site) that I keep a print of showing all the bolt set ups. A handy reference me thinks.