Triumphrat

Snakeoil

On my '66 T120R, I found two rings at the base of the pushrod tubes instead of the cups shown in the parts book, part E4746. I looked at the '65 parts book and it has nothing there, just the seal. I cannot find a parts book that shows rings instead of cups.

I'm about to install my head and noticed that the rings are very loose and really only rest on the tappet blocks. I assume that the seal at the bottom will expand as I tighten down the head, but not 100% confident it will expand enough to hold those rings in place.

Should I use the cups instead? Or will the rings work once the head is down and the seals compressed?

Thanks,
Rob

tintop48

rob, not sure what you mean by rings,but to me without the upturned flange on the cups i would be concerned that the compression on the seals might push them out of shape

Snakeoil

They are not washers. They are tubular rings, like a napkin ring. I suspect this was the first attempt at restraining the expansion of the seals.

Rob

DaveDone

Hey Rob, I am not sure about the '66 but the ring on my 76 pushrod tube base is referred to as a sleeve in the book. It doesn't have a bottom- just sides and the seal is large enough to expand and lock it down ( with a little silicone) You could try a dry run to see if you are happy with the squish.

were they leaking ?

__________________
Dave

Snakeoil

Thanks Dave. Never thought to look to later model years. Thought the ring was an earlier design.

I just looked at my '76 parts book and it also shows an o-ring in conjunction with the seal. Does the o-ring go between the seal and the pushrod tube or around the seal such that it is positioned between the OD of the seal and the ID of the sleeve.

And yes, it would appear that I have the later design sleeve. Yet I found no o-rings when I disassembled the engine.

regards,
Rob

Garioch43

Hey Snakeoil,

You'll see from the '76 parts manual that the bottom of the pushrod mates with an O ring - part number 70-7310, which then sits on a thick plastic sealing ring - part number 70-4752, all of this is retained inside a metal sleeve - part number 71-1707, which slides over the tappet block and is compressed when you bolt down the head.

__________________


Sam Murray

Aberdeen, Scotland

Caulky

There are two O-rings.
The top one fits over the PRT.
The lower one sits inside the lip of the base.
The tube sits on the white sealing ring, which is over the tappet block.
The base of the tube and its seal is constrained by the sleeve.
Fit the sleeve and the white seal over the tappet block first.
Then offer up the head and tubes, complete.

Snakeoil

Cauky,

I'm trying to understand the positioning of that lower o-ring. I suspect I'm struggling because the 750 motor PRT is different. Are you saying that the o-ring fits inside the PRT and the ID of the ring seals againd the OD of the upper half of the tappet block? That would indicate that the bottom of the PRT is formed channel rather than a simple flange like it is on mine. That would also say that the o-ring is the first seal and the PRT white rubber seal ring is the second seal.

If my understanding above is correct, then I'm limited to just using the sealing ring and the napkin ring to restrain the sealing ring from extruding out from under the PRT.

There is another slight variation for these older motors. The front (exh) PRT needs to be installed in the head before you present the head to the jug with the engine in the frame. The rear,(inlet) needs to be installed on the tappet block.

regards,
Rob

Caulky

Snakeoil
Forget my previous post.
Sorry for the mis-info
There were several arrangements over the years.
After doing a bit of research, I found the following:
`65 (and earlier?) 650`s have 70-3646 tubes. (alloy head)
70-1496 lower seal, black rect. section (thick)
70-3547 top seal 2.5mm thick
No cup/sleeve.

`66 to `68 had 70-6000 tubes
70-3547 top seal, white 2.5mm rect. section.
70- 4752 lower seal, white 3.5mm thick rect. section
70-4746 cup

`69 to `73 had 70-9349 tubes.
71-1707 sleeve
71-1283 top O-ring
70-7310 lower O-ring (fits inside the tube)
70-4752 bottom seal

You might like to view these:
http://www.classicbike.biz/triumph/P...artsManual.pdf `65
http://www.mapcycle.com/parts-finder...-head-tr6.html `68

Snakeoil

No sweat, Caulky. I knew you were talking about a T140 config.

But, I will argue with your finding regarding the seals used on a '66. My manual shows the E3547 2.5mm seal used top and bottom (qty 4). So does the manual for the '66 on the Classicbike site. But for the '67, the manual on the Big D site shows the 3.5mm lower seal and the 2.5mm upper. Yet Classic bike '67 Tiger manual shows the 3.5mm , E4746, top and bottom.

How's that for British clarity at it's finest?

So, somewhere between DU24875 and DU44394 the PRT seals went from 2.5mm up and down to 2.5 top and 3.5 bottom to 3.5 top and bottom. Then in '69 it went to E7310 which is an o-ring.

I need to measure the amount of crush to be sure I'm using the correct seal rings.

It would have been so much simpler if they had simply cut a doube o-ring groove in the tappet block and put a square sealing ring at the bottom.

regards,
Rob