TM  10-3930-643-34 ENGINE,  FUEL,  EXHAUST  AND  COOLING  TROUBLESHOOTING  AND  MAINTENANCE. 4-4. Cylinder Head Assembly with Valves. ADJUSTMENT NOTE l Adjustment is to be made on a warm engine. l All valves are adjusted by only 73. 74. 75. cranking the engine twice. Remove valve cover, refer to para- graph 4-6. Turn crankshaft until number one piston is on the compression stroke and timing pointer on front cover is in line with the TDC mark (pin) on vibration  damper. Do not adjust valves with engine running. Severe damage can result if feeler gage is inserted between valve and valve lever due to close clearance of valve to piston. NOTE Be sure that the number one piston is on the compression stroke. Turn both push rods by hand until both valves are closed. Valves are closed when push rods are loose and can be turned easily. (Sheet 17 of 18) Go to sheet 18 4-45