Travel adjusted by stops Valve adjusted correctly “In” stop prevents grinding the stem Out In Workhead table 2" Stone Shield Figure 10-24.  Valve installed in grinding machine.  Figure 10-25.  Valve in chuck ready to grind.  Figure 10-27.  Grinding a valve tip.  Figure 10-26.  Engine valves showing normal margin and a feather  edge.  Feather edge Normal margin and forth. Do not swing the valve stem off either edge of the  stone. Because of the tendency for the valve to overheat during  this grinding, be sure plenty of grinding fluid covers the tip. Grinding of the valve tip may remove, or partially remove,  the bevel on the edge of the valve. To restore this bevel,  mount a V-way approximately 45° to the grinding stone.  Hold the valve onto the V-way and twist the valve tip onto  the stone. With a light touch, grind all the way around the  tip. This bevel prevents scratching the valve guide when the  valve is installed. After the grinding procedure is finished, it is sometimes  necessary that the valve be lapped to the seat. This is done by  applying a small amount of lapping compound to the valve  face, inserting the valve into the guide, and rotating the valve  with a lapping tool until a smooth, gray finish appears at the  contact area. The appearance of a correctly lapped valve is  shown in  Figure 10-28 . Valve Lapping and Leak Testing 10-17