ARMY TM 9-2815-260-24 AIR FORCE TO 38G1-126-2 MARINE CORPS TM 09244A/09245A-24 5-108 (g) Resurface cylinder head as follows: 1 Resurface cylinder head if cylinder head thickness is less than the minimum acceptable thickness of 4.104 in. (104.24 mm).  Remove only what is necessary to restore flatness. 2 Combustion face surface finish (surface grind only) should be 31 - 125 micro-in. (0.7 - 3.2 micrometers).  Maximum wave depth is 0.0005 in. (0.012 mm). 3 Recheck cylinder head flatness, refer to step 4 (e). 4 Recheck cylinder head thickness, refer to step 4 (f). 5 Recheck valve recess in cylinder head, refer to paragraph 4.7.4.b. FIGURE 5-91.  MEASURING CYLINDER HEAD THICKNESS __________ WARNING Compressed air used for cleaning can create airborne particles that may enter the eyes.  Never exceed 30 psi (207 kPa) of pressure.  Eye protection required.  Failure to comply could result in serious eye damage or blindness. (h) Clean injection nozzle bores with nozzle bore cleaning tool.  Blow debris from bore with compressed air. (i) Clean and measure valve guides as follows: 1 Clean valve guides with plastic brush and a few drops of light oil or kerosene. 2 Measure valve guide inner diameter using telescopic gauge and record measurements