Valve spring retainer cap issues

[RSK55]

Hi, I'm not technically an E-type owner but the engine's the same, so I'm hoping someone can throw some light on a problem I’m struggling to find answers to.
I’m currently building up the original 3.4 SE block and head for my XK140.
The head has been machined, new valve seat inserts and valve guides fitted, by a very experienced machine shop in the midlands who have a lot of experience in XK engines. I’m now doing the assembly.
I have new valves, springs, spring seats, collets and valve caps.
When I assemble these new parts into the head, I then give the valve stem tips a few decent taps with a hammer and brass drift to settle the collets in the caps, then start the shimming work.
I'm finding that some of the shims are sitting in the recesses on the caps by only about 0.003-0.004". Given that the valve clearance on the exhaust cam is 0.006", this means that the shim has approx 0.002" space under it that could allow it to slip sideways in the tappet when the cam is on its base circle. This could cause a lot of damage. When setting the valve clearances on the bench, some of the shims can slip sideways off the valve stem tips unless held in place with oil/grease. The caps and collets are SNG Barratt.
If I substitute an old valve cap for the new one, using the same new collets, valve, springs etc., the shim fits into the top by at least 0.009-0.010", thus holding the shim nicely in place. Anyone else had this issue? I could just use the original valve caps, but I have fitted valve stem oil seals so need the shorter modern cap to clear the seals.
It's not the valves or the new inserts, I've checked dimensions and everything's right. The difference appears to be in the valve spring retainers (caps) themselves, between the old, longer type and the shorter modern ones.

[Gfhug]

RSK55, please add your name so we can answer you much more politely than just by your moniker.
By valve caps I presume you mean collars (C27480, the old number is C2159)? What thickness of shims are you using? One way to get a bit more space is to ground down the tip of the valve stem, though you’d have to machine this properly to be square or your clearance will not be consistent. Also you need to be able to still fit a within range shim so be very careful how much is taken off.
Is the problem on the exhaust only or on the inlet too?
How do the valve collars, old and new, compare for depth for the shims without the valve in?

Have you asked this “experienced” engine company for their thoughts? That would be my first port of call as they are the ones who have done all the work.

Hope the above helps

Geoff

[christopher storey]

I don't think that I understand ..... once the shim is fitted to the recess , and tappet bucket is fitted on top of it , there is no clearance between any part of the valve train itself. The valve clearance is between the upper surface of the bucket and the heel of the camshaft, and the outside diameter of the shim very closely accords with the internal diameter of the valve cap ( as you call it) so that it certainly should not be able to slip sideways i.e.radially. Are you sure you are using the correct shims , and not the much later ones for e.g.XJ40 engines which are smaller in diameter ?

[RSK55]

Sorry, the name is Roger!

I'm a bit hesitant to contact anyone involved in the work on these parts until I can ascertain exactly where the problem lies. The machine shop did the head work, supplying valves, springs, tappets, valve guides (fitted - later type to take stem seals) and fitting new valve seat inserts. I then purchased shims (as a set), spring seats, collars and collets. I bought the later style of collar as the originals are too long and do not clear the stem seals. In retrospect it would have been more sensible to ask the machine shop to supply everything to ensure compatibility.

I have set the valve clearances to 0.006" exhaust and 0.004" inlet, using shims ranging from 0.096" to 0.101", which I believe to be a fairly typical range but am ready to be corrected. The problem lies with a number of valves in which the valve stem sits quite high under the top face of the collar - see photo.
I appreciate that with the tappet held down onto the shim there is no clearance, but if the tappet did not move with the collar when that valve is on the back of the cam a gap matching the valve clearance could appear between the underside of the tappet and the shim. If the shim is only located by 3thou and the clearance of an exhaust valve is 6thou, that shim could slip sideways and cause problems.

As said, I have assembled all the new components but substituted one of the old valve collars, and these typically give somewhere between 0.009-0.012" for the dimension shown in the photo (at 0.0035"). I can't use the old caps with stem seals as they are longer.



This is my first Jag engine - I know small block Ford V8s inside out, but OHC is new territory for me. Colleagues on the XK forum (Jag Lovers) have suggested I ask here as there is a lot more knowledge out there in E-type world! I don't know these engines well enough to make the call - if the tappet always stays stuck down on top of the shim, there isn't a problem. If it can stay up slightly when off the lobe, I could have a problem. If assembling these parts dry, I have to prop the side up I'm working on, otherwise some of the shims will slip down during assembly. I'm told this isn't correct. This is the original SE block and head to this car so I really don't want to risk any damage.

[christopher storey]

Roger : I'd like to see a picture of one of your shims in place before the bucket is fitted. It would be easier then to visualise what you mean by slipping sideways

Incidentally, I hate to say this , but if your valve stems are too high, then it is highly likely that there has been the equivalent of valve seat recession in the installation of the new valve seats

[Gfhug]

Roger, welcome to the forum, yes there’s a lot of knowledge here. Can you measure the diameter of the shims, please, to see if Christopher’s comment is appropriate. Edited to say Christopher has effectively asked you the same by taking a photo.
And fit a shim into an old and new collar to compare the depths in each collar. How much is there above the groove on the valve stem to take a bit off?
Yes, your shims are in the middle of the range, without doing the calcs I’m not sure how much you could safely take off the valve stem. It looks like a few thou could be taken off without going too far, but get it properly machined and only on the stems that really need it.
Christopher, (and others) do you agree to that as a solution?

Regards

Geoff

[RSK55]

Thanks for the input, both, very helpful.

Photo of a shim in place - held it with a spot of assembly lube.




Diameter of shims is 11/16".

To help illustrate the bit I don't understand, here are two photos. Both are of the same valve, with the same collets. The tight one is using the new, short collar, the loose one is with the original, long collar.






I know these are not ideal in that there is no spring compression here, but both were gently tapped into place with a brass drift.
I reckon that either there was more to the design change in the collars than merely reducing their height, or the modern replacements are not made to the same dimensions. If all my shims would sit at 12thou below the collar height there would be no problem at all. These are the SNGB collars.
I don't get it - surely half the restored Jags out there would have this problem, as these seem to be the only collars now available? Jag classic have discontinued theirs.
It seems to me that the aftermarket collars have the taper that the collets sit in placed less deep than the originals. This is very difficult to measure, but the collets definitely sit more deeply in the old collar than the new. Car has done 77,000miles, not that much for a 67-yr-old.
I don't really want to have to find a machine shop to reduce selected valves by varying amounts, so I may end up having to ditch the stem seals and reverting to the original caps, which would be a shame.

[abowie]

That's not right.

Somewhere along the line you've got a mismatch between valves, retainer and collets.

There are 2 different lengths of collets, and different retainers. I don't think they're mix and match.

I'd reuse your original retainers and collets.

You should have no trouble fitting stem seals EBC3531; these press down over the top of the valve guide and stick up 0.250" at most. If they don't fit then there is a problem with your seals.

Also, as a sanity check, the top of the valve stem should sit 0.850" below the machined face for the cam cover.

[RSK55]

The only collets fitted in my photos are new short ones from Rob Beere Racing. Collets and retainers came together from RBR - I’ll check that valve stem height dimension in the morning, thanks.

[mgcjag]

Hi Roger.......there are only 3 parts involved here as Andrew mentioned above...valve, collar, collet.......the valves are from your engine builder...the collets, collar from Robb Beere.....have you still got your original valves...is so try an original valve, collar, collet and check what space you have to fit a shim......at least then you have your base line to work from......then on an original valve mix and match collar, collet to see what happens......I cant say what depth the shim usually sits in the collar as iv never measured it...but i think its even more than in your 12thou photo above...my thoughts are it sits in around 1/16in....they usually drop in with plenty of space to "rock" them to ensure they are sitting on the valve and not on the collar.......Steve

[christopher storey]

I should send this entire thread to Rob beere and ask them if they can help . As Andrew Bowie says, somewhere there looks to be a mismatch

[RSK55]

Thanks all, I really do appreciate this advice.

Having a fiddle through it again today, inbetween making up the hard fuel lines.

First thing to report as that the valve stem tips are all at, or very close to (within 1-2thou) 0.850" below the machined surface for the cam covers. Typically, 0.0851". That's a relief - it looks even more like a parts issue rather than machining. David Knight does a beautiful job and I'm very pleased with his work. Having had experience of several engine machine shops over the years, he has impressed most (I've never had the machined parts back in heavy duty sealed plastic bags before!).

[RSK55]

...and here is an original valve with its original keepers and collar:



Now that's much more like it - as so many of you have said, there is a parts mismatch here (a thought - why on earth didn't I do that before??) I am very relieved that it doesn't look like a fundamental (=expensive) problem.

[mgcjag]

Hi Roger.....how does the original valves compare to the new ones.....is the recess cut in tne same place....Steve

[RSK55]

Yes, it must be - if I assemble old collets and old collar on the new valve I get 25thou, same as the original valve.
I've just tried a third sample new collar and it is also wrong. Of course these may all be coming from the same supplier ultimately, but for obvious reasons no-one will tell me who makes their parts so I can't be sure.
For peace of mind, I think I'm going to have to use original collars with original collets on the new valves. I'll have to experiment to see if the stem seals will be a problem. The old collars are deeper than the new ones, which must be for a reason.
Does anyone know the reason why the collets and collars were redesigned, presumably pretty early on in the XK engine's life? abowie says in his post that the seals will not be affected, although I have been told this was the reason for the change.

[christopher storey]

AFAIK, the first fitment of valve guide seals was on the big valve engines for the Series 3 XJ6. This was right at the end of the XKs production life . I think you had better consult Rob Beere's , who should be able to give you a definitive answer

[RSK55]

Thanks Christopher, I'll do that.
Going back through the paperwork I note that the collets are Beere's own uprated type to reduce the risk of 'pull through', presumably not very likely under the driving conditions I will be experiencing in a 3.4 XK140DHC!
I'll check with Rob - they are a very helpful company.

[Fred]

Gents,
I have a 1968 Series 1.5 (original owner) and my engine has valve guide seals. Don't have experience of the problem at issue but wanted to let you know that valve guide seals were well before Series III XJ6 (which we also had back in the day).
Best regards,
Frederick

[RSK55]

Frederick - cheeky question, but I don't suppose you know which type of valve collar/spring retainer you have? Does it have a taper at the lower end, or is it longer and parallel all the way down?
Fantastic, owning a car like that for 54 years!

[RSK55]

I think I’m making some progress on this. To try to get the bottom of the problem I ordered a single valve collar from Moss Europe, purely on the basis that in their photo their version is a different colour.
It arrived today, and is clearly of a different manufacture from the SNGBarratt offering (which Beere’s also supplied). It is short, the same length as the SNGB one, but does not have the tapered end the others all seem to have (but the longer original did not have).

Here’s a photo of it assembled with the new valve and new collets:



and a reminder of the SNGB version, assembled with exactly the same parts:



a loose 25thou clearance against a tight 3.5thou.

Clearly these two have been machined differently. I should give both Barratt’s and Beere’s a call to make them aware of this, I think - I don’t think I’m imagining it…