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TR6 Valve Collets


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Hello.

I hope that I am not repeating an existing thread but searched for ages .. I am trying to ascertain the correct valve spring/ collar/ collet combination. I have two early PI engines for my late 72 TR6.  Each engine had different collars between the Inlet valve (single piece collar) and the Exhaust valves (two piece collar). I have new valves (standard) and with the Inlet valves the collets do not fully insert into the Single piece collar, whereas the Exhaust valve collets sink down snugly into the two piece collars. I note that the single piece collar on the inlet does have a step to force alignment of the inner valve spring whereas the two piece does not. Is there any reason why I could not install the two piece collar system on all valves.

In addition I am unsure whether I should use the stepped washer under the springs as it was installed on one engine and not on the other.

Could someone please set me straight on this. I am in New Zealand and in the Register there but we have drawn a blank on this issue.

Thankyou in advance. Peter Wilson

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Good Morning Peter, and welcome.

I have changed your topic title to TR6 Valve Collets, this will give you a much greater chance of receiveing answers, and

enable 'Searchs' in the future to be more succesful.

John.

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Hi Peter and welcome.

I had the head off my CP series TR6 a couple of months ago. The valve cap and collet arrangement in mine is identical to your photo.

Nigel

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Hello all.

Many thanks for your replies and ideas. I am still uncertain whether there is anything preventing me from installing the exhaust valve double collar to all valves, thus replacing the single collar on the inlets. I will attach a photo showing how badly the inlets collets seat down into the single collar. As an engineer I find it hard to accept yet there has to be a reason why the Triumph designers settled on having a different setup for the inlet compared to the exhaust.  The fact that both valves have double springs means binding could be an issue and one of the collars (the single) gives positive location for the small spring. But can you think of any reason why that would be more important on the inlets than the exhausts?  Regarding the stepped washers which I will install they do give a preload to the small spring so have a dynamic effect as well as preventing wear on the head.  

BTW incredible though it may seem, my two heads one fitted to a UK PI car and the other to a USA carb car, ended up with me in New Zealand and the serial numbers are only 2 digits apart, ie only one head in between the two in production!

Anyway I am near to assembly but want to try to clarify this first. If not I may have ot revert to the original set-up.

Regards Peter Wilson

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The double caps on the top of the exhaust valves are to allow the valve to turn in operation, apparently not necessary for the inlet.

Collars at the bottom are to stop the valve springs eating into the head soft cast iron.

The collets look as if they would have been different for the inlet tops, and so this would cause confusion in assembly. Perhaps the tops where from an older model and so not neccessary for a redesign.

John

 

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Hi Peter,

I'm coming into this late. All 1972 model TR6 from CC75001 and CP75001 had single valve springs and a different collar to the earlier TR6 when they left the factory. This was done by Triumph to commonise with the rest of the six cylinder range. Commencing at CR1 and CF1 they reverted to the double spring arrangement utilising the same outer spring but in conjunction with a stepped collar.  Incidentally your two heads are identical, assuming they are 218225 ( PI) and 218227 (carb) apart from head height and the carb head can be skimmed by 135 thousands of an inch to increase the compression ratio to the same as the PI. The PI standard head height being 3.4".

Derek  

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Thankyou all for your feedback.  Your info John L that the double collar was to allow valve rotation makes me feel I will go with the double collars for all valves since it must be an advantage for all the valves to be able to rotate surely??  My engines are CF3156UE  and CP75266HE with the CF being modified to PI spec by the chap who did the conversion LHD to RHD and set the car up for track use.  So from what you are saying Derek the engines both would have been fitted with single valve springs. Since both now have double springs this was obviously changed over the years. I have new springs coming from Moss for the spare engine (CP) but can rob parts from it to set the CF up as best I can. It (CF) has new valves, new guides and seats,  new rocker shaft and cam followers, new cam gears (vernier cam gear), 2 ring PI cam. So unless anyone can definitely advise against it I will assemble it up in the next days with all double collars, stepped washers, double springs. Thanks again folks and hope you are all able to stay safe over there. Regards Peter

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This is CR head but the valve collets look the same as yours.

 

 

head.jpg

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  • 1 year later...

I had some trouble with the coils almost binding (1.55)....the "uprated" collars seem to work better but they are made from aluminium. And with the steel ones the collets do not sit deep enough. So I make them myself. The actual series will be made from titanium and/or quality steel with a better fit. The collars are larger in diameter so the spring is completely covered. If any interest, send me a PM. 

Jochem

ValvaCollars1.jpg

ValvaCollars2.jpg

ValvaCollars3.jpg

Edited by JochemsTR
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  • 8 months later...

Old thread I know but by way of confirmation  of how useful the forum is. I'm working on starting an early CP engine (TR5) which has been locked up for a very long time, have it freed up and rotating now but decided to strip the head and give it some attention. I noticed on disassembly that there were differences between the valve spring collet collars, didn't know why but great to see that its been addressed here, I note that somewhere back along the line the head had been reassembled with the collet collars randomly installed. Now changed to 2 piece on the exhaust and 1 piece on the inlet. Great forum.

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I have just re-built the cylinder head on my 1971 TR6, 3 of the exhaust double collars had cracked, these are no longer available

& have been replaced with the single inlet type. If you look in the triumph parts catalogue page no 09-34 part no 128334 is 

superceded by 111870.

 

                                                       Harvey

 

          

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Moss are showing them as available (the twin  collars). 

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HI TRier

              I ordered the twin collar type from MOSS  & the single type inlet arrived. I contacted MOSS & they assumed they had been picked wrong.

We then checked the part no from the Triumph parts catalogue. & this showed no stock.I then checked the catalogue more closely & realised

this showed the 2 part numbers for the same item. If you order the small exhaust inner collar ( the outer is still in stock at MOSS ) their parts

catalogue will cross reference to the inlet cap. 


                                                             Harvey

 

 

 

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Thanks Harvey, thats a bit of a bummer, personally I'd rather have them as intended. The way the collets sit in the single collar ones just looks insecure to me I must admit, they've been that way a long time so obviously its OK, just looks ropey. I wonder does it not matter then in practice that the exhaust valve can't rotate as originally intended?

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Just an update on the two part exhaust valve collar. With regard to them spinning out of the six exhaust valves 

in my engine only one had been turning in operation, the seat was still nice & shiny & looked like new after

approx 120.000 mls. All the others were the usual black.

                                         Harvey 

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