Cam Tappet ( or Bucket ) shims

[trunt]

When doing my valve clearances I had a few shims that needed to be below the 0.090 minimum that Triumph supplied and others were near so I was worried that once the engine was in they could also drop below that figure.. Initially I thought I would need to have the valves ground down a few thou to make sure they were inside the available shims.

So I did a bit of digging. apologies to any other forums that I stole info from!

These shims are used on quite a few types of engine, most notably Jaguar Lotus and SAAB 99's

However it seems that Jag, Lotus, Imp etc used 5/8" (15.875mm, 0.625") diameter shims. But Aftermarket suppliers then made these as 15.55mm diameter shims to allow them to also fit other engines including the Triumph Saab 99 and 900, (Maestro and Montego 1.7 and 2.0, and Rover 2.3, 2.6 engines but some have reservations on using shims with beveled edges)

So any of these could be a source of under 0.090 shims, just check the diameter.

In the end My Jaguar friend had a box of them, and quite a few were the smaller size and thickness (aftermarket?) I needed.

[v8ken]

Thanks Terry,
I remember doing similar digging when I did mine,although when swapped around,I found that I only needed a couple.
Ken.

[andybaulf]

Nice to have a Jag friend who could supply under sized (thickness) shims. Fortunately having overhauled a Mk2 Jag, imps (3), Triumph TR7 and recently my Stag, I was very lucky to have the use of a surface grinder. For those of us who are now retired and out of meaningful engineering employment there is an alternative, albeit a rather torturous method. Get a sheet of fine emery cloth, lay it on a very flat surface and start rubbing the shim on it till it gets down to correct thickness. You can fit the shims and check valve clearances. if not right, remove and keep on rubbing. Fingers get a bit sore and I have got my son to turn up a holder for the shim to fit into thus saving finger wear.

[Mark Serj]

Are the shims hardened? Any danger of getting into soft material?

[andybaulf]

No. If they were emery cloth wouldn't touch them. By the way all my cars ran perfectly well and valve/cam clearances were fine for many years.

[trunt]

alternative, albeit a rather torturous method. Get a sheet of fine emery cloth, lay it on a very flat surface and start rubbing the shim on it till it gets down to correct thickness. You can fit the shims and check valve clearances. if not right, remove and keep on rubbing. Fingers get a bit sore and I have got my son to turn up a holder for the shim to fit into thus saving finger wear.

Yes
I did that for a thou or two correction but would hate to try that for much more with the shims at a couple of quid each (actually free in my case) I'm not retired yet soon!

But I'm guessing going forward, now that I have a good set I can correct any small changes by doing exactly that.

[TR5convalescent]

Andy, do you do this dry, or with a drop of oil or water?

Thanks.

David

[JOHNS]

An alternative method is to use a sheet of glass with different grades of emery paste. This method can also be used to grind engine components such as damaged manifolds or cam covers etc.

[mjheathcote]

When I have swopped mine I have a friendly Lotus specialist who is happy to pull out his supply of twin cam shims.
Have also swopped with members of our local area, a sort of pool of shims!

[GDPR]

I've got a load of much thicker ones - 0.120" to 0.140" - Rover 2300/2600 shims that may come in useful when I get a cam presented with a reduced base circle for higher lift

[jbuckl]

imho dont grind the valve stem ends, they are hardened, albeit to a lower hardness than the head of the valve.
imho dont grind the shims more than 4 thou, they are hardened, but can be changed slightly more easily than the valves if they go through to the soft & wear! (ive seen 'hardened standard' shims that have over 5 thou sinkage at the stem contact diameter)
Sub 100 thou shims are / were available (ex e series s series, r series o series climax, lotus etc).... not sure that the chamfered type cause a problem though.
Please let me know what that problem might be?
AFAIWA the chamfer was to be able to work with a smaller diameter bucket, so might not work if a non-chamfered shim was used in a smaller diameter bucket...... pretty sure the other way is ok though.

[jbuckl]

Glad to see you are still here & posting
Keep on keeping on

I've got a load of much thicker ones - 0.120" to 0.140" - Rover 2300/2600 shims that may come in useful when I get a cam presented with a reduced base circle for higher lift

[trunt]

.... not sure that the chamfered type cause a problem though.
Please let me know what that problem might be?

Just quoting what I saw elsewhere on this forum.. The fear was that they could work their way out, My thoughts were that if they are sitting high on the valve it sounded reasonable. I edited my initial post to make it less... Final!

On my head at least they are sitting differently on some valves. I think the stems are routinely "dressed" during a valve job here. I also noted that the keepers (collets) are somewhat variable and cause the stem to sit a little higher if they are thicker, lower if they are thinner.

TBH I have never seen a chamfered one, are they chamfered both sides? If not then putting the chamfered side to the top could work. Bottom line is that there are plenty of non chamfered ones available, no reason to risk it?