I once pulled apart a SBC that had a trashed thrust bearing and trashed thrust surfaces on the crank. The engine had not been apart before. When I went to reassemble the engine with a different crank, the end play went to zero when the cap was tightened. I checked the side clearance between the thrust surface of the loose bearing and the crank with a feeler gauge and it looked perfect. I tried the whack it back and forth technique to no avail. It still tightened up when the cap bolts were torqued.
On further examination, I noticed that the corner where the thrust sides of cap and block met the main bearing surface was sharp. There was no chamfer from the factory. When the cap was tightened, that sharp corner pushed into the inner radius of the bearing and flared out the thrust surfaces of the bearing against the crank thrust surfaces. This factory defect had trashed a nice forged factory crankshaft.
I chanfered the corners by hand with a die grinder and all was well from there.
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