Triumphrat

Caulky · 04-20-2009, 05:27 AM

Hi
Given that the stroke of both models is 82mm, why are T140 head bolts longer (1mm)?
I`m really interested in the length of the push-rod tubes.
I have a feeling that someone in the past has fitted T140 tubes to my 1974 T120V.
If the T140 tubes are longer, it would explain why I have several issues with tightening the head bolts...something very odd here.
Some time ago, I ordered a set of stainless T140 head bolts, but I have a feeling that they are `bottoming`, rather than torqueing the head.
If I rest the head and tubes onto the barrels, there is an excessive gap, in my opinion.
I thought the heads were similar, except for the extra stud hole.
The T120 push-rod tubes are 71-2575/70-9349, whereas the T140`s are 71-3329. Mmm, very strange!
I dont really want to buy more tubes, if they are the same length.

GrandPaulZ · 04-20-2009, 11:03 AM

They are different length pushrod tubes.

A LOT different. you can't just swap 'em.

jimmy bush · 04-20-2009, 11:45 AM

I think the pushrod tubes are a different length because of changes made to the tappet guide blocks and the holes where the push rod tubes fit in the head have been recessed deeper on the later heads. I think the head thickness should be the same (with emphasis on "I think") so the head bolts should work. I have seen two different thickness washers under the head bolts. When you ordered yours, did you get washers with them or just the bolts? Maybe you need the thicker version under your particular bolts. (I am assuming that we are discussing headbolts after 1971 when they changed the design to accomodate the frame clearance issues.)

mark61120 · 04-20-2009, 04:03 PM

Something(s) to bear in mind with parts on our 1974 T120V's;

When they were built and the circumstances they were built under.
What they were built from.

These bikes were built during a window in the strike and from bits that were left in the bottom of the boxes marked 650, much of the parts are interchangeable with the T140V. It is possible that your engine was built as you have it, with the wrong push-rod tubes installed.
It is possible that every 650 made during 1974/75 was unique in some form or another as it left the factory. You never know!

Mark