I agree, the thrust bearing should fit correctly, without hand-fitting, but it depends on who did the crankshaft grinding, and the radius they put on the shaft where the bearing area meets the thrust face. If you look at the edge of the bearing surface, next to the vertical area for the thrust face, there should be a rounded transition, not a square corner. If the radius is too broad, the bearing will not fit onto the flat part of the shaft. It's called "radius ride", and is responsible for a lot of bearing failures on the thrust bearing. In the "crankshaft specifications" part of any good service manual, there's an "end play" spec. That's the amount of front-to-rear movement the crank is supposed to have, and it's controlled by the thrust bearing. If you use a feeler gauge beside the thrust bearing, you can figure end play before the bearing is installed. For instance, a .005" feeler gauge clearance between the thrust flange and the crank will translate to the same amount of end play with the bearing installed. If it's necessary to adjust end play, I use a piece of plate glass, some lightweight oil, or cleaning solvent, and a piece of 400 grit wet-or-dry sandpaper. Lap the bearing thrust face (ONLY, not the round part) in a figure-8 motion until the clearance is correct. if both bearing shells have thrust faces, (most do), make sure clearance is equal on both bearing shells, and that the adjustment is done on the same side. Another method is to have the crank grinder measure the bearing shell, and grind the correct clearance into the crankshaft. Any good crank grinder should do that as part of the regrinding procedure, but some don't bother to fit thrust bearings correctly. Fittng a thrust bearing, using the procedure I've described, is a last-resort method to save a problem job!
Good luck!
Jerry
