Valve Spring Inspection
Valve Spring Free Length and Preload
Referring to data given below, check to be sure that each spring is in sound condition, free of any evidence of breakage or weakening. Remember, weakened valve springs can cause chatter, not to mention possibility of reducing power output due to gas leakage caused by decreased seating pressure.
Valve spring free length
Standard: 36.83 mm (1.450 in.)
Limit: 35.83 mm (1.410 in.)
Valve spring preload
Standard: 107 – 125 N (10.7 – 12.5 kg) for 31.50 mm (23.6 – 27.6 lb/1.240 in.)
Limit: 102 N (10.2 kg) for 31.50 mm (22.9 lb/1.240 in.)
Spring Skewness
Use a square and surface plate to check each spring for squareness in terms of clearance between end of valve spring and square. Valve springs found to exhibit a larger clearance than limit given below must be replaced.
Valve spring skewness
Limit: 1.6 mm (0.063 in.)