ARMY TM 9-2815-257-24 AIR FORCE TO 38G1-128-2 MARINE CORPS TM 10155A/2815-24/3 5-28 5-11.  CYLINDER HEAD MAINTENANCE  -  cont. C.    INSPECTION. 1. Inspect cylinder head (1, Figure 5-17) for cracks, on,  and  deformation.    Replace  cylinder  head  if damaged or deformed in any manner 2. Inspect   stems   of   valves   (15,   16)   for   wear   or distortion.  Measure the outside diameter (OD) of the stems (Figure 5-18).  OD shall be 0.2323 inch (5.90  mm),  minimum.    Replace  valve  if  stem  is out of limits. 3. Measure  the  internal  diameter  (ID)  of  the  valve guides  (installed  in  cylinder  head).    ID  shall  be 0.2394   inch   (6.08   mm),   maximum.      Replace cylinder head (1, Figure 5-17) if valve guide ID is out of limits. Figure 5-18.  Valve Stem OD 4. Inspect   valve   springs   (12)   for   cracks,   broken sections,   or   deformation.      Replace   spring   if damaged or deformed in any way. 5. Measure  free  length  (non-compressed)  of  valve springs (Figure 5-19).  Length must be 1.240 inch (31.5  mm),  minimum.    Replace  valve  spring  if less than required length. 6. Insert  valves  (15,  16,  Figure  5-17)  into  cylinder head  (1).    Measure  valve  sinkage  (Figure  5-20).   Sinkage shall be 0.043 inch (1.1 mm), maximum.   If sinkage exceeds limit, discard valves.         Figure 5-19.  Valve Spring Length Figure 5-20.  Valve Sinkage