more Triumph pushrod tubes

I am working on a T120 1971. 9-hole head. 650. leaf spring trans.
I have two sets of pushrod tubes. over all measurement is 5 7/16.......and......5 1/16. I could be off a whisker because I measured with a ruler.
These are TOO LONG and TOO SHORT. I am doing a bit of mixing and matching. The head has the deep pockets for the pushrod tubes. I have a good selection of square section o-rings. Is there a THIRD LENGTH that I don't know about?

I think there are way more than 3 lengths in the total Triumph twin product lifecycle / range. Triumph changed things regularly in this area, tubes, seals, head machining, tappet blocks, barrel height, etc.

So what mix n match of parts you have is really anyone’s guess.

Opinions differ, but I try and aim for 0.030” of ‘crush’ on the seals. So whatever mixin’ and matchin’ you do, if you shoot for this you should be ‘dry’ (ish) IMO.

Don’t ever be tempted to use hardware store stock o rings. Stick to buying proper seals for the job. Stock o rings are likely to fail… ask me how I know

Fast Eddie said:

I think there are way more than 3 lengths in the total Triumph twin product lifecycle / range. Triumph changed things regularly in this area, tubes, seals, head machining, tappet blocks, barrel height, etc.

So what mix n match of parts you have is really anyone’s guess.

Opinions differ, but I try and aim for 0.030” of ‘crush’ on the seals. So whatever mixin’ and matchin’ you do, if you shoot for this you should be ‘dry’ (ish) IMO.

Don’t ever be tempted to use hardware store stock o rings. Stick to buying proper seals for the job. Stock o rings are likely to fail… ask me how I know

Click to expand...

You didn't fit the orange O rings up top did ya?

baz said:

You didn't fit the orange O rings up top did ya?

Click to expand...

I fitted the ‘bottom’ ones up ‘top’ on my T140 much to the predictions of doom of some of yooz guys, but they’ve been fine.

The one I had fail once (over 25 years ago) was when I used a ‘standard’ o ring from a set. That split and got spit out and was a nightmare !

Fast Eddie said:

I fitted the ‘bottom’ ones up ‘top’ on my T140 much to the predictions of doom of some of yooz guys, but they’ve been fine.

The one I had fail once (over 25 years ago) was when I used a ‘standard’ o ring from a set. That split and got spit out and was a nightmare !

Click to expand...

A shop fitted the bottom (orange ones non heat resistant) to the top of my mates t140d
These lasted about 50 miles until both let go, pissing oil out front and back
We were on our way to Cornwall from London for a week
We stopped in shepton mallet
I went in to Charlie's in Bristol to get a top end gasket set and seals
And we pulled the head outside the pub and rebuilt the top end
It's never leaked again as far as I know

Fast Eddie said:

I think there are way more than 3 lengths in the total Triumph twin product lifecycle / range. Triumph changed things regularly in this area, tubes, seals, head machining, tappet blocks, barrel height, etc.

So what mix n match of parts you have is really anyone’s guess.

Opinions differ, but I try and aim for 0.030” of ‘crush’ on the seals. So whatever mixin’ and matchin’ you do, if you shoot for this you should be ‘dry’ (ish) IMO.

Don’t ever be tempted to use hardware store stock o rings. Stick to buying proper seals for the job. Stock o rings are likely to fail… ask me how I know

Click to expand...

There should be a white "flat washer" (70.4752) at the bottom with a ring (71.1707) to keep it from squeezing out. There should be a thick (1/8"?) o-Ring at the top. I think the "crush" from head sitting there loose to torqued is more like .060" but the important part is that the head must be supported by the tubes with a gap to the cylinders/head gasket before installing head bolts - it may well be .030" crush, just seems like more to me.

I am familiar with all that. Next question, is there a difference in lifter blocks? These have the oil feed

seattle##gs said:

I am familiar with all that. Next question, is there a difference in lifter blocks? These have the oil feed

Click to expand...

Yes there are differences, but I couldn’t list them for you.

Too much crush is worse than too little imo
Ok just slightly less than the good book says
But too much crush can cause real issues if it spits the seal out

How to Suck Eggs .

Sit the tube / tunnels on the lifter block , No seals . Sit the head on . Rattle them , rotate them , lift & drop them . ( no head gasket ) .
Throw 1/16th or 1 mm ply or plastic ' in place ' to lift head . even . ( say four headbolts dropped in ) REPEAT .

The IDEA is to check end float , concentricity , and straightness . As In the Ends are Good . Some Turkeys even bended Pushrod Tubes .
wheres my 4 x 2 . Thatll get the motor out - get them off . Er . . .

SO , therefore Then , as all the ALIGNMENTS FAMILIAR , and We're all Finger tippy feely ready . Fitting the seals , dry , carefully ,
cautiously dropping things on , after seating them with a finger tip and CLEAN socket end or tube , judiciously dropping the head / headbolts in . ALIGNED .
as in the heads placed , A SPACER or say 1/8 ply strip Both sides , the head'll sit flat - clear . Drop in four headbots and fingertip wind in 1/2 way .

CAREFULLY lift head SQUARE , After checking tube rotation & lift ,pull spaces , and GENTLY lower head square on to seals - tubes . SQUARE .
GLARE across head gasket gap , Hum & haw . see how head MIGHT sit dead flat , with about 2 or 3 mm ' crush ' left . SQUARE . With Lamp .

So , Therefore , thereafter , it should all pull down in square ( as youve just checked all that ) Without butchering , nicking , or crushing the seals to billyo .

in theory . the next question is omlette or Soffle .

A hand each side , head on , at the CHECKING STAGE , you can pull it down flat to about 1 mm . even & square . So as THAT is the CRUSH . fully tightened .
Shaved Heads and things wottle get ya , can make em ' mix n match . So triumphestte have a liddle box of Pushrod tube ' accesories ' to hand . if they have a dozen .

There are a dizzying array of push rod tubes and seals. I assume it's because they all leaked. When I built my T100 I used the tube that came with the box of parts and they matched the parts book. The base of the tubes looked irregular so I used wet/dry paper on glass to check that the surface was true. It was not so I worked until the top and botton surfaces were flat. I used the white square cut seals that were called for. I placed the head dry, with the head gasket, on the tubes, head bolts in place but not tight, and used a feeler gauge to check the head clearance. This is close to 0.060". This is the controversial part, I then I used Permatex Copper Spray-A-Gasket on the seals. I was using it on the head gasket so I though "what the heck, why not." (It says it can be used on AC fittings.) I gave the seal a light coat and then carefully fit them over the tappet block. At first I was a little concerned when it didn't leak because I had no indication that the top end was getting oil. Subsequent investigations proved it was. It is still dry after a couple of hundred miles.