Valve clearance shims?

Allanxantia · Post by **Allanxantia** » 10 Jul 2005, 20:41

I have just overhauled the head but need to re-shim the valves. Trouble is that having lapped the valves most of the valves have no gap and in fact valves must not be sealing correctly. Is there an easy way to work out what shims I should use. Was going to order a variety from the thinnest up and use a bit of trial and error, then order more of the ones I need. I cannot get into a dealer during their opening hours so was going to get some sent out. Does anyone know what sizes they come in, what is the thinnest etc Xantia 1.9D. and a rough idea of cost?
Any help appreciated

AndersDK · Post by **AndersDK** » 10 Jul 2005, 21:21

Most garages have a box with a wide selection range of shim thicknesses. Either you may rent the box - or they offer a pr shim swap for a small fee.
Get a haynes on any later car with OHC engine. They always have the shim calculation procedure in the engine chapters. It really is the best description.
As you have lapped in the valves you may need to bring at least 1-2 of your old shims and then get a full set initially 1.0mm less. As you need a too large valve clearance (to have the valves closed) to calculate the correct shim.
They come in 0.05mm increments (being approx 3mm thick total) - so it really is possible to get the clearances spot on. Forget about grinding/rubbing the shims. They are incredible hard steel.

fastandfurryous · Post by **fastandfurryous** » 10 Jul 2005, 21:26

I've no idea how much these shims cost, as all I've ever done is use ones from scrap engines, and now have a fairly large collection of them. My local engine reconditioner also has a massive supply.
Although a metric engine, these shims are actually manuafactured in thousandths of an inch. From memory they are available in the range from abour 110 thou to about 140 thou. If your valves aren't even closing, you will have to use a nominal thickness of shim (much thinner than you have in at the moment) and measure clearances to be able to work out what ones you need.
Or, if the valves are too sunk into the face of the head, then you may have to have the stems of the valves ground shorter. I had to have this done when I had my 1.9TD engine done. I got my reconditioner blokey to remove 30thou from every valve stem so that I was able to use standard thickness shims, otherwise I would have had to order/make specially thin shims.
It is indeed a pain. Quite what was wrong with adjuster screws and locknuts I really don't know! Far easier.

citronut · Post by **citronut** » 10 Jul 2005, 21:49

if you have only laped valves in and put valves and shims in same place as they came out you should have some clearance,what is your working knoledge of engine repairing and are you checking the gap on the rear of cam loab not on the peak,as youy must have the peak pointing up away from valve to check the gap regards malcolm

Kowalski · Post by **Kowalski** » 11 Jul 2005, 03:59

Adjuster screws and locknuts are far too expensive for cars these days...

jeremy · Post by **jeremy** » 11 Jul 2005, 04:12

The shim adjustment system used on most modern cars is derived from the systtem used on the Jaguar XK engine in 1948. in its day this engine set new standards for power output and reliability and one of its major achievements was the provision of double chain driven camshafts that would last the lifetime of the engine with nothing more than the manual adjustment of the top chain (easy)
Prior to that time OHC had been treated with some suspicion and tended to be troublesome or noisy or both.
The drive was used almost unaltered on the last XK engine produced in about 1990 and the shim adjustment system looks like lasting many more years.
jeremy

Post by **Peter.N.** » 11 Jul 2005, 04:23

Take it to your local friendly engine reconditioning firm, they will probably do it for you for not to much money.

Kowalski · Post by **Kowalski** » 11 Jul 2005, 04:46

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jeremy</i>
The drive was used almost unaltered on the last XK engine produced in about 1990 and the shim adjustment system looks like lasting many more years.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
I think that the shim system being on the XK engines, in fact the fact that the XK engines were in production for so long was a symptom of the British car industry going down the tubes. It was a bit of "if it ain't broke don't fix it" and a lack of will or money to develop anything better.
Hydraulic tappets seem to be the fashionable thing now, no adjustment required as long as they don't gunge up.

bxbodger · Post by **bxbodger** » 11 Jul 2005, 04:56

How much did you take off-It must have been a lot to end up with no clearance at all!!!
They should only really need adjustment if the seats have been recut or replaced.
My experience of shim systems on petrol as well as diesel is that I have never had to change one, even after quite a severe lap and grind on a rattly old R series Maestro.........
Your best bet would be to contact an engineering shop wher they do heads-there are loads of them about The one I use,Fields in Leyton, are very good are very good and they will sell you a single one if you need it and tell you what sizes they have as well. Most recondotioning shops will do the same.

Mosser · Post by **Mosser** » 11 Jul 2005, 05:08

If you go down to your local peugeot garage, the shims are about 2 quid new, but there will be a 2 day delay as you have to give them the sizes you want, they order them and they come in next day

Allanxantia · Post by **Allanxantia** » 11 Jul 2005, 07:17

Thanks for the replies. Engine has no compression on middle 2 cylinders with cam in. but full compression with cam out! I am also getting exhaust soot up the inlet tracts slightly. I bought it as a non-runner so it is a bit trial and error. checked all clearances against the back of the lobe and all the exhaust are OK, well at least they have a gap. Just really need to get smaller shims for the inlet valves, I am going to leave the exhaust valves alone, as long as I can get it running I can re-adjust later. All I really need is 1 shim, thinnest I can get and use that for my calculations! cheers guys!

citronut · Post by **citronut** » 11 Jul 2005, 13:34

how do you do compression test with cam out,sounds like it has had a cam belt go and it has bent valves,or some one has had head off and not done job properly regards malcolm

Allanxantia · Post by **Allanxantia** » 11 Jul 2005, 14:22

I have just had the head off skimmed lapped in all the valves etc. with cam out all the valves are closed. I did this to try and confirm my thoughts of valves not seating correctly due to clearance, which I am now confident is the problem. With the head off, pouring fluid into each valve tract, nothing leaks out at all so the valves seat well. As I said there is no gap at a couple of them with the cam in so I am certain I will need to re-shim. Unless I am mistaken?

jeremy · Post by **jeremy** » 11 Jul 2005, 14:36

Yes you need a clearance. I suppose the problem you've got is that as the valve isn't shutting you can't get the first clearance from which to start the calculation.
As I see it your alternatives are to grind a little off the end of the valve stem - difficult as you really need to remove the head etc and then make up a jig to hold the thing square against a grindstone.
Or take the shim out and measure. I've never had one of these apart but assume the tappet would sit on the valve properly and enable you to measure.
Or make up a thinner shim of soft metal (mild steel) and use it to start off the arithmetic. The problem with this would be making sure your improvised shim was flat so that it could be measured accurately.
jeremy

Mosser · Post by **Mosser** » 11 Jul 2005, 15:23

much easier to just get down the pug garage this morning and order their thinnest shim, collect it tomorrow morning and you can start measuring, you never know, they might have a bx of used loose shims that you can pick from, take your micrometer along !