TM 10-3930-664-24 3. Clean     cylinder     head     assembly     and     related components  in  hot  soapy  water  solution.    Allow to air dry. 4. Polish valve  stems  using  crocus  cloth.    Remark valves for location in cylinder head. C.  INSPECTION 1. Conduct    general    inspection    of    cylinder    head assembly components in accordance with paragraph 1-24. 2. Inspect   valve   guides   for   scuffing   or   scoring. Measure  valve  guide  bore  (dimension  A).    Bore diameter   shall   not   exceed   0.3157   in.      (8.019 mm). 3. Inspect cylinder head surface for nicks, erosion, or      damage.            Check      for      head   distortion. Variation  within  any  2  inch  diameter  area  shall not exceed 0.0004 in. (0.01 mm). 4. Inspect  for  abnormal  wear  on  valve  heads  and stems. Measure valve stem diameter (dimension    B).        Diameter    shall    not    exceed 0.3134 in.  (7.960 mm). 5. Check  valve  seat  angles  for  distortion.    Intake angle must be 30 degrees.  Exhaust angle must be 45 degrees. 6. Measure  valve   head   rim   thickness   (dimension C).    Thickness  shall  nor  exceed  0.031  in.  (0.79 mm). 4-11