Shim box, or grinding?

[tofts]

Is there a forum shim box? Have been on car forums in the past where there is one?

If not, could I grind and re-harden the existing shims. I think my local machinist can do Cyanide hardening, will have to ask later. Failing that, would a heat and quench be sufficient?

I know I could just buy, but I like doing things myself If I can, just to try it mostly!

J

[ukkid35]

I sanded mine by hand, using various grades ending up with a fine polish. Takes a long time, but no chance of getting them too hot. I don't know anyone else who does it by hand, most people grind them.

[RichV6]

Hand sanded mine on a combination of a cheap diamond lap and fine carborundum paper on a surface plate. Skin on my fingers still recovering.

[tofts]

Interesting, and this won't effect the hardness of the shims then? Yours have been ok thus far?

[RichV6]

so far they have been fine

[ukkid35]

Done this twice; when I did it for the second a couple of months ago I could see from my records which I'd sanded and which had not needed adjusting (most of the exhaust), and there was no sign of change in the shims at all.

[greenracing]

I sand by hand also and you get a much more accurate result than putting in a new " correct size" shim. This is due to the valve top not being completely smooth but also I found the new shims did not have a well defined inner edge so they actually sat a little proud of the valve top.

[spitfire4v8]

For many years I've lapped shims down on a carborundum stone .. It works great if you only need 1 or 2 thou taking off. If you see an engine that's obviously not had its clearances done for some time, and you need 5,6 or 7 thou taking off, you're probably better off buying a new shim the correct size. Taking a shim down 6thou is not fun ..

[ukkid35]

spitfire4v8 said:

Taking a shim down 6thou is not fun ..

First time I did this all the intakes needed at least 12 thou removed, I watched a lot of TV while sanding them.

[tofts]

Great stuff, thanks for all your input Guys (or girls?)

From this then, i presume that the case hardening effectively penetrates the whole shim because of the size?

Edited by tofts on Sunday 3rd May 13:30