TM 10-3930-660-34 3-7. CYLINDER HEAD ASSEMBLY - REPLACE/REPAIR  (Cont’d) f. Apply a light coat of valve lapping compound to each valve and lap valve to its companion service seat. g. Remove valves from cylinder head and clean grinding compound from valves and service seats. h. Measure width of service seats. Valve Service Seat Width Range Limits Minimum J: 0.060 inch Maximum K: 0.080 inch i. If service 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 h above. j. Stamp two X’s on side of cylinder head in line with pocket with service seat. 6. MACHINE PARENT METAL EXHAUST VALVE SEAT POCKETS AND INSTALL EXHAUST Valve seats marked with one X at side of cylinder head have been ground once and if regrinding is necessary, install service seat. a. Machine parent metal intake valve seat pocket to the dimensions shown. 3-46 N = 0.3157 - 0.3165 in. P = 0.015 in. radius max. Q = 0.3975 - 0.4055 in. R = 1.7180 - 1.7190 in. dia. S = 1.7489 - 1.7589 in. dia. T = 0.1379 - 0.1479 in. U = 0.0157 in. radius max. V = 128 micro inch surface finish