just try it without the shims, you shouldn't need any, unless you have purposely ground the crankshaft too large. I really see no connection between shims and the crankshaft seal? Yes from the factory in original installations they did come with shims, but in present times, when you are replacing them with modern present day insert bearings, I don't see it. Except for the bit about it being a '48, for present day replacement bearing sets from Egge at least, up to '48 they provide shims, '49 and beyond they don't provide shims. That may just be Egge. I don't know what the criteria they are using for this discrepancy (difference?) Being that yours is a '48, I don't know? You can always just measure the ID, and the OD and subtract to get the difference, or simply set it in place, and being very careful, slowly tighten down the caps making sure the crank continues to turn freely , if it does, then you can use plastigage. Unless of course you are enjoying the battle with the shims.
