This leaves a looser fitting rod than when the engine was originally built. Engines Plus cuts the valve seats to 3 angles and installs bronze valve guides. We surface the heads to the correct finish that the gasket companies require and we grind the valve stems and faces of valves to insure their straightness, size and fit. We reclean all the machined parts including thoroughly recleaning the oil galley holes before assembly. We assemble the heads with high temperature silicon valve stem seals.
Many companies still grind the valve seats with stones.
This is not a precise way to machine seats. They do not cut the seats to 3 angles. They knurl guides instead of replacing the guides. Very few companies reclean the machined castings before assembly. They simple wipe of the machine dust and assemble.