Discovery II
ENGINE - V8
OVERHAUL 12-2-65
11. Check the following valve dimensions. Renew
valves as necessary.
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Valve head diameter 'A': Inlet = 39.75 to
40.00 mm (1.56 to 1.57 in).
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Valve head diameter 'A': Exhaust = 34.23 to
34.48 mm (1.35 to 1.36 in).
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Valve stem diameter 'B': Inlet = 8.664 to
8.679 mm (0.341 to 0.342 in).
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Valve stem diameter 'B': Exhaust – 4.0 litre
engines up to engine nos. 55D 05677A; 56D
50787A and 97D 05504A = 8.651 to 8.666
mm (0.340 to 0.341 in).
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Valve stem diameter 'B': Exhaust – 4.0 litre
engines from engine nos. 55D 05678A; 56D
50788A and 97D 05505A and all 4.6 litre
engines = 8.641 to 8.656 mm (0.340 to
0.341 in)
12. Check installed height of valve.
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Valve installed height, end of valve to base
of spring seat, 'C' = 44.163 to 45.288 mm
(1.741 to 1.802 in).
13. Check condition of valve springs. Valve
springs must be replaced as a complete
set.
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Valve spring free length = 48.30 mm (1.90
in).
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Valve spring fitted length = 40.40 mm (1.59
in).
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Spring load - valve closed = 339
±
10 N (76
±
2.25 lbf).
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Spring load - valve open = 736
±
10 N (166
±
2.25 lbf).
14. Check valve stem to guide clearance using the
following procedures:
15. Insert each valve into its respective guide.
16. Extend valve head approximately 13 mm (0.6
in) out of valve seat and position a DTI gauge
to rear of valve head.
17. Move valve towards front of cylinder head and
zero DTI gauge ensuring that stylus of gauge
remains in contact with valve head.
18. Move valve towards rear of cylinder head and
record gauge reading to give valve stem to
guide clearance.
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Valve stem to guide clearance 'D': Inlet =
0.025 to 0.066 mm (0.001 to 0.002 in).
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Valve stem to guide clearance 'D': Exhaust
– 4.0 litre engines up to engine nos. 55D
05677A; 56D 50787A; 97D 05504A = 0.038
to 0.078 mm (0.0015 to 0.003 in).
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Valve stem to guide clearance 'D': Exhaust
– 4.0 litre engines from engine nos. 55D
05678A; 56D 50788A; 97D 05505A and all
4.6 litre engines = 0.048 to 0.088 mm
(0.0019 to 0.0035 in).
19. Renew valve guides as necessary.
20. Using valve guide remover tool LRT-12-037
press valve guide into combustion face side of
cylinder head.
21. Lubricate new valve guide with engine oil and
with tapered portion of guide leading, insert
guide from valve spring side of head.
Note: Service valve guides are 0.025 mm
(0.001 in) oversize on outside diameter to
ensure an interference fit.
22. Fully fit guide using tool LRT-12-039A and
distance piece tool LRT-12-208
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Valve guide installed height 'A' = 15.00 mm
(0.590 in).
23. Ream valve guide to 8.70 mm (0.342 in).
Note: Service valve guides are supplied with an
internal diameter of 8.1 mm 0.025 mm (0.319 in).
24. Position cylinder head stands and mount
cylinder head on stands.
25. Check valve seat insert for pitting, burning,
cracks and wear. Replace as necessary.
Service valve seat inserts are available 0.025
mm (0.001 in) oversize on outside diameter to
ensure interference fit.