TM 10-3930-660-34 3-7. CYLINDER HEAD ASSEMBLY - REPLACE/REPAIR (Cont’d) If GD is greater than 0.010 inch, a service valve seat must be installed. g. With valves in their designated bores, measure and record depth I. Depth Limit I Depth: 0.039 - 0.060 inch h. If depth I exceeds tolerance limits, replace the valve and  check depth I again. i. Apply a light coat of valve lapping compound to each valve and lap each valve to its companion seat. j. Remove valves and clean grinding compound from valves and seats. k. Measure valve seat width. Valve Seat Width Range Limits Point J: 0.060 inch Point K: 0.080 inch l. If valve seat is too wide after lapping, grind lower seat surface L using a 600 seat grinder, and upper seat surface M with a 150 seat grinder until seat width is centered and within specifications listed in step k above. NOTE If it was necessary to install service valve guides, STEP 3,install the service guides before installing the service seats. 3-44