Isuzu 4JA1 Workshop Manual page 89

Valve Spring Free Height
Use a vernier caliper to measure the valve spring free height.
If the measured value is less than the specified limit, the valve
spring must be replaced.
Spring Free Height
4JA1T (L)
4JA1TC,
4JH1TC
011LX024
Valve Spring Squareness
Use a surface plate and a square to measure the valve spring
squareness.
If the measured value exceeds the specified limit, the valve
spring must be replaced.
Spring Squareness
4JA1T (L)
4JA1TC,
014RY00025
4JH1TC
Valve Spring Tension
Use a spring tester to measure the valve spring tension.
If the measured value is less than the specified limit, the valve
spring must be replaced.
Valve Spring Tension
4JA1T (L)
011LX026
4JA1TC,
4JH1TC
ENGINE MECHANICAL 6A – 67
Standard
Single spring 48.0 (1.89)
Single spring
Compressed
Height
Single 38.9mm
spring (1.53in)
mm (in)
Limit
47.1 (1.85)
mm (in)
Limit
1.7 (0.067)
N (kg/lb)
Standard Limit
296.0 257.7
(30.2/66.4) (26.3/57.9)