Stovebolts have a nasty habit of wearing a dimple in the tips of the rocker arms where they contact the valve stems. That usually results in a noisy valve train because the true clearance can't be set with a feeler gauge, or a chewed-up feeler gauge if it's inserted between the rocker and the valve with the engine running. Some valve grinding machines have an accessory designed to reface rocker arms, but there's a lot of controversy about how accurate a radius can be done that way. In my decidedly biased opinion, a smooth rocker tip is better than one with a big hole in it regardless of how technically accurate it might be.
Jerry
I have had good results by using a bench grinder with a very fine grit wheel with a steady hand, keeping the rocker surface aligned with the wheel, and rolled the rocker as best as I could to match the curved surface. I checked progress after every pass.
The nice thing was, the divot in the rocker arm followed the same radius as the original unworn surface, so all I had to do was roll the rocker arm and remove metal so that, as it went away, its contour matched that of the divot until there was only a minute amount of the divot remaining.
I then switched to cloth polishing wheel loaded with jeweler's rouge until the divot was gone.
