ARMY TM 9-2815-259-24 AIR FORCE TO 38G1-125-2 MARINE CORPS 09249A/09246A-24 5-109 (b) Put valve springs on flat surface to insure that valve springs are square and parallel.   Replace all defective valve springs. (c) Measure valve spring free length.  Free length of valve spring should be 2.125 in. (54.4 mm).  Replace valve spring if not within specifications. (d) Test valve spring tension with spring compression tester (DO1168AA).  Replace valve spring if not within specifications. 1 At 1.81 in. (46.0 mm) height, valve spring tension should be 54 - 62 lb-force (240 - 280 N). 2 At 1.36 in. (34.5 mm) height, valve spring tension should be 133 - 153 lb-force (590 - 680 N). (2) Inspect valve rotators to insure that valve rotators turn freely in both directions.  Replace if defective. (3) Clean, inspect, and measure valves as follows: __________ WARNING When using bench grinder, eye protection must be worn to prevent particles from entering eyes.  Failure to comply could result in serious eye damage or blindness. CAUTION Do not use wire wheel on plated portion of valve stem.  Failure to comply could result in damage to valve and valve guide. (a) Remove all carbon from valve head, face, and unplated portion of valve stem using a soft wire wheel on a bench grinder. (b) Polish valve stem with steel wool or crocus cloth to remove any scratch marks left by wire brush. (c) Clean and inspect valves, valve stems, valve stem tips, and retainer lock groove for cracks, wear, or evidence of physical damage.  Replace valves that are worn or damaged. (d) Measure valve stem outer diameter with outer diameter micrometer.  Record measurements and compare with valve guide inner diameter, refer to step 4 (i).  Replace valves not within specifications. NOTE Intake valve has a larger head outer diameter and is also identified with a dimple on valve head. 1 Intake valve outer diameter should be 0.3096 - 0.3104 in. (7.864 - 7.884 mm).