ENGINE,  FUEL,  EXHAUST  AND  COOLING 4-4. Cylinder  Head  Assembly  with DISASSEMBLY/CLEANING/INSPECTION 27. 28. 29. 30. 31. Check valve stem ends. If grind ends square. TM  10-3930-643-34 TROUBLESHOOTING  AND  MAINTENANCE. Valves. (Sheet 9 of 18) worn, Resurface valve face angle, if necessary. Maintain valve face margin, as shown. A minimum margin must be maintained of 0.088 inches for intake valves-large head (14) and 0.045  inches  for  exhaust  valves-small head (13). Maintain valve face angles, as shown. Valve must be replaced if more than 0.008 inches of stock is removed or margin falls below minimum specification in Step 31. After resurfacing, check valve face runout with dial indicator. NOTE Valve must be replaced if total indicator  reading  is  greater  than 0.002 inches. Check  valve  face  contact  with Prussian blue. Bluing  should  appear around  entire  contact surface  of valve face and valve seat. If bluing does not appear around entire contact surface, angles do not match. Valve seats must be resurfaced. Go to sheet 10 4-37