A fellow racer has a 4.5" bore x 4.25" stroke, Crower crank large short snout, BME 426 rods, A460 block, blown alky BBF that had a thrust bearing failure. Estimated HP was 1600+. Using a slipper clutch. What could cause the thrust bearing to fail ? Improper crank end play ? Something to do with the clutch assembly ? Looks as though the crank could be toast as the thrust surfaces are quite bad. Any experiences or ideas on why this could happen ? This is just for my own knowledge as the racer has already built another engine(BBC) and moved on and is not really interested to know why this happened.