ARMY TM 9-2815-252-24 AIR FORCE TO 38G1-92-2 TABLE 3-4.  Cylinder Head Component Wear Limits Component Initial Maxims Dimension Clearance inches (mm) inches (mm) Hydraulic tappet diameter 0.842 (21.386) 0.843 (21.405) (0.11) Hydraulic tappet bore 0.8435 (21.425) 0.004 0.8445 (21.450) Valve spring free length 1.72 (43.7) (See Note Below) 1.79 (45.5) Valve guide bore - 0.283 (7.195) installed 0.285 (7.250) Valve stem diameter 0.2817 (7.155) 0.0065 (0.165) 0.2823 (7.170) NOTE Replace the spring if the length is 1.67 in.  (42.5 mm) or less. b.  Check that intake valve seat is sunk 0.037 to 0.05 in.  (0.95 to 1.26 mm) and exhaust valve seat is sunk 0.052 to 0.065 in.  (1.33 to 1.64 mm) below combustion surface.  If not, regrind valve seats, refer to paragraph 3- 27.4. c.  Check cylinder head clearance as follows: NOTE This procedure is used to determine what size head gasket is required.  Start with medium size gasket. (1)    Place  head  gasket  onto  crankcase.    Align  holes  in  gasket  with  those  in  crankcase.    Rotate  engine  so pistons are below cylinder head deck. (2)      Using   a   very   small   amount   of   general   purpose   grease   630AA),   place   four   pieces   of   solder (SN60WRAP2) size 0.062 in.  (1.58 mm) thick on pistons as shown in FIGURE 3-30.  Space solder on outer edge and as near as possible in line with piston pin.  Care must be taken to ensure that solder will be clear of valve recesses. (3)  Install cylinder head and torque bolts, refer to paragraph 3-27.6. (4)  Manually rotate engine through two complete revolutions. 3-58