V8 Engine Overhaul - Valves, Springs, and Guides Inspection
ENGINE
OVERHAUL
9
4. Check valve head diameter A:
Inlet = 39.75 to 40.00 mm (1.56 to 1.57 in)
Exhaust = 34.226 to 34.48 mm (1.34 to 1.35 in)
5. Check valve stem diameter B:
Inlet = 8.660 to 8.680 mm (0.340 to 0.342 in)
Exhaust:
Standard and carbon break valves fitted to
early engines = 8.651 to 8.666 mm (0.340 to
0.341 in)
Modified carbon break valves fitted to later
engines = 8.641 to 8.656 mm (0.336 to 0.340
in)
6. Check installed height of each valve C:
Valve installed height C:
Standard and carbon break valves fitted to
early engines = 47.63 mm (1.9 in)
Modified inlet and carbon break exhaust valves
fitted to later engines = 44.163 to 45.29 mm
(1.741 to 1.802 in)
7. Check valve stem to guide clearance D using
the following procedures:
8. Insert each valve into its respective guide.
9. Extend valve head approximately 13 mm (0.6
in) out of valve seat and position a suitable dial
test indicator to rear of valve head.
10. Move valve towards front of cylinder head and
zero dial test indicator gauge ensuring that
stylus of gauge remains in contact with valve
head.
11. Move valve towards rear of cylinder head and
record gauge reading to give valve stem to
guide clearance:
Inlet valves - Early and later engines = 0.025 to
0.066 mm (0.001 to 0.002 in)
Exhaust valves:
Standard and carbon break exhaust valves
fitted to early engines = 0.038 to 0.078 mm
(0.0015 to 0.003 in)
Modified carbon break exhaust valves fitted to
later engines = 0.048 to 0.088 mm (0.0019 to
0.0035 in)
12. Repeat above procedures for each valve in
turn.
13. Renew valves, guides and valve seat inserts
as necessary.
CAUTION: If modified valves and guides
are to be fitted, they must be replaced in
engine sets.
14. Check condition of valve springs:
Free length = 48.30 mm (1.90 in)
Fitted length = 40.40 mm (1.60 in)
Load at fitted length = 339
±
10 N (76
±
2 lbf)
Load at valve open length = 736
±
22 N (165
±
2 lbf)
CAUTION: Valve springs must be replaced
as a complete set.