Stainless Steel Disc Shims to match your requirements, see below.
When I first started building these engines I found there was nothing available to correct the valve tappet clearances; the tappets themselves are no longer in production and any off-the-shelf stragglers tend to command a 3-figure sum, each. So by taking a leaf from the high-revving motorbike world I came up with this effective solution instead...
These handmade disc shims fit between the valve tip and the tappet. They're used to correctly set the valve clearance between cam lobe & tappet when new valves are installed and the correct thickness tappet isn't available.
If you're replacing valves it's recommeded that new valves used with existing tappets are first sorted into pairings which suit the available shim sizes. Think 'longest valve (as fitted) to the thinnest tappet' and vice versa.
Tappets have their thickness marked on the underside which makes this process a bit easier; I usually make a note of each tappet's thickness & fitted position along with the measured valve clearance to determine what the ideal tappet size for that position would be. I then look at the ideal vs actual values of the tappets across that cam and see if any can be swapped around to make the numbers more favourable, matching either the required valve clearance directly or by using the shim sizes available to make up the difference.
Shims should not be stacked.
The tolerance and specification for the valve clearances are;
0.15 - 0.21 mm INLET
0.28 - 0.33 mm EXHAUST
+0.01 or .02 mm looser than the suggested setting might be better on an engine intended to run at high speed using a thicker oil.
Shims are available in the following sizes, please specify size & quantities when ordering;
0.05mm / .002"
0.08mm / .003"
0.10mm / .004"
0.13mm / .005"
0.15mm / .006"
0.20mm / .008"
0.25mm / .010"
0.40mm / .015"
0.50mm / .020"