Working on a 1991 Toyota pickup 3L V6. Needed to change the valve covers, so while I am in there I decided to check valve clearances. Founf that 2 are on the tight side. The shims seem to be hard to get. My question is, are these shims flat?? No spherical or concave surfaces on the shim? I am asking because I just need to change the clearance on 2 shims. If they are indeed just flat, then I will take them out and take them to work and grind them down to fit my needs. I guess I forget to mention that I am a machinist by trade and I would be doing this on a surface grinder. What do you think??

Thanks

 

What machinist doesn't always have a 1" (25mm) mike in his (her) pocket?

I've measured these a few times; as far as I can tell with my micrometer, they are flat on both sides.

As far as buying them, I've used my local dealer, and an online dealer. For a while, someone on eBay was selling them in packs of four; if they were a usable size for you it was a good deal. I can't find it now.

 

I had a friend who has a surface grinder, cut several shims down when I adjusted the clearances on my 3vz. No problems.

Be sure to grind the bottom of the pucks, so that the existing wear pattern between the shim and the cam are not disrupted.

Another good reason to mill only the back of the shims is that they may well be case-hardened, and it would not be wise to expose any (potentially) softer surface to the cam lobes.

 

Note that the shims are designed to rotate in use (to even out the wear, or as millball hints, create a particular wear pattern).

Yotatech member MudHippy claims to have successfully ground shims on the side of a bench grinder wheel. If the shim isn't almost perfectly flat (uniform), it probably won't rotate correctly. But I suppose if you're very careful ....

If you have a real surface grinder, that shouldn't be an issue.

Personally, I would be surprised if the shims are hardened (case or otherwise), as I would think it would risk damaging the cam. But I don't know, and there's no reason to not follow millball's advise and to only grind on one side.

 

Scope-
Those shims are near as hard as glass.

(at least the genuine Toyota ones are)

I could'nt mark one with a good Solingen knife.

 

I just did mine and sourced the replacements from Cylinder Head Supply (Oregon); $20 for a set of four. The shims seem flat and my reading indicated that people had been successful grinding them to tolerance (which is the only way to get a shim that isn't in increments of .05mm). Having said all that, I have a surplus of shims and if you are willing to wait on the post, am willing to sort through what I have to see if I have the thickness you need. Just let me know what sizes you need and I'll let you know if I have them in the box.