Figure 12-53 Measuring Valve Spring Tension Figure 12-55 Valve / Seat Grinding Figure 12-54 Measuring Valve Spring Length Repair Figures 12-55 through 12-58 Valve Grinding Pitted valves must be refaced to the proper angle. Valve stems that show excessive wear, or valves that are warped excessively must be replaced. When an excessively warped valve head is refaced, a sharp or thin valve margin may result because of the amount of metal that must be removed. Undersize valve margins lead to breakage, burning, or preignition due to heat localizing on this knife edge (figure 12-55). Refer to “Specifications”.
If the edge of the valve head is less than specification after grinding, replace the valve. Several different types of equipment are available for refacing valves. The manufacturer's instructions for how to use the equipment should be carefully followed to attain the proper results. Figure 12-56 Critical Valve Dimensions Figure 12-57 Measuring Valve Seat Concentricity G643 (E) Service Manual Chapter 3. Engine Mechanical System 88