The shims are essentially "wear shims". That is they could be removed one by one as the crank journals/bearings wore thereby allowing you to adjust rotational clearances without removing the crank. This was done using the amp load system. That should be in your shop manual. I completed the rebuild of my 235 recently and because I have a recut (.010/.010) crank with new undersize bearings I had to shim .002 on just one cap to get the proper clearance measuring with Plastigage.
I think if I had the block line bored I probably would'nt have needed that shim.
In short, check your clearances. You may not need any shims until your next rebuild.
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Drew
'55 Chevy
