It may seem excessive, but Marvin inspects and cleans up the lifters with a fine stone to remove any nicks and edges that could cause stress risers, friction, and potential failure. While there, check the C-clip for proper retention and the roller for proper installation and smooth operation. Check all surfaces for any irregularities. Bore-to-lifter clearance should be .001-.0025 inch. Treat the lifter bore with the same respect and attention you would each of the cylinders. This is very important for oil control and smooth operation.