Inspection

Valve Guides
Using micrometer and bore gauge, take diameter readings on valve stems and guides to check stem to guide clearance. Take reading at more than one place along length of each stem and guide.
If clearance exceeds .0027 inch for intake stems or .0035 inch for exhaust stems, replace valve and valve guide.

Valves

Fig. 31 Measuring Valve Head Thickness:

Fig. 32 Measuring Valve Stem End Face:

Fig. 33 Measuring Valve Radial Runout:

Fig. 34 Measuring Valve Seating Contact Width:

1. Remove all carbon from valves.
2. Inspect each valve for wear, burn or distortion, replace as necessary.
3. Measure thickness of valve head Fig. 31. If measured thickness exceeds .023 inch for intake valves or .027 inch for exhaust valves, replace valve.
4. Inspect valve stem end face for pitting and wear. If pitting or wear of stem end face is present, valve stem may be resurfaced, providing that its length will not be reduced to less than .14 inch. If length becomes less that specified, valve must be replaced Fig. 32.
5. Using dial gauge, check each valve for radial runout Fig. 33. If measure runout exceeds .003 inch, replace valve.
6. Inspect seating contact width on each valve as follows:
a. Apply a uniform coat of red-lead paste to valve seat.
b. Tap each seat to valve head. Valve lapper tool must be used.
c. Pattern produced on seating face of each valve must be a continuous ring without any break, width of pattern must be within .0512-.0590 inch, Fig. 34. Any valve seat not producing uniform contact or showing seating contact that is off the specified width must be repaired.

Cylinder Head

Fig. 35 Measuring Cylinder Head Distortion:

1. Inspect cylinder head for cracks in intake and exhaust ports, combustion chambers and head surface.
2. Using straightedge and thickness gauge, check gasketed surface at six locations Fig. 35. If distortion limit of .002 inch is exceeded, correct gasketed surface with a surface plate and abrasive paper. If abrasive paper fails to reduce thickness gauge readings to within specifications, replace cylinder head.
3. Inspect manifold seating faces in same manner as step two. If distortion limit of .004 inch is exceeded, correct in same manner as step two. If thickness gauge readings are not within specifications, replace cylinder head.

Valve Springs

Fig. 36 Measuring Valve Spring Squareness:

1. Ensure valve spring free length and preload are within specifications.
2. Using square and surface plate, check each spring for squareness, Fig. 36. Springs that exceed .079 inch out of square must be replaced.