Discovery 2. Manual — part 442

ENGINE - V8

OVERHAUL 12-2-61

9. Remove cylinder head gasket.

CAUTION: Support both ends of cylinder
head on blocks of wood.

Inspect

1. Clean mating faces of cylinder block and head

using suitable gasket removal spray and a
plastic scraper, ensure that bolt holes in block
are clean and dry.

CAUTION: Do not use a metal scraper or
machined surfaces may be damaged.

2. Check head and block faces for warping and

pitting.

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Maximum cylinder head warp = 0.05 mm
(0.002 in).

Note: Cylinder head can be refaced to 0.50

mm (0.02 in) maximum below head height –
See cylinder head overhaul.

Reassembly

1. Fit cylinder head gasket with the word TOP

uppermost.

CAUTION: Gaskets must be fitted dry.

2. Carefully fit cylinder head and locate on

dowels.

3. Lightly lubricate new cylinder head bolt threads

with clean engine oil.

4. Noting that bolts 1, 3 and 5 are longer than the

remainder, fit bolts and tighten in the sequence
shown to 20 Nm (15 lbf.ft) then turn through 90

°

, then a further 90

°

. CAUTION: Do not

tighten bolts 180

°

in one operation.

5. Clean the push rods, Lubricate ends of push

rods with clean engine oil, and fit in their
removed order.

6. Clean bases of rocker pillars and mating faces

on cylinder head.

7. Clean contact surfaces on rockers, valves and

push rods.

8. Lubricate contact surfaces and rocker shaft

with clean engine oil.

9. Fit rocker shaft assembly and engage push

rods.

10. Fit rocker shaft bolts and progressively tighten

to 40 Nm (30 lbf.ft).

11. Connect ht leads to spark plugs in their correct

fitted order.

12. RH cylinder head: Position alternator

mounting bracket, fit bolts and tighten to 40 Nm
(30 lbf.ft).

13. RH cylinder head: Fit auxiliary drive belt

tensioner.

14. Fit inlet manifold gasket.

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ENGINE - V8, OVERHAUL, Gasket -

inlet manifold.

ENGINE - V8

12-2-62 OVERHAUL

Cylinder head - overhaul

$% 12.29.19.01

Disassembly

1. Remove cylinder head gasket.

+

ENGINE - V8, OVERHAUL, Gasket -

cylinder head.

2. Loosen screw on tool LRT-12-034.

3. Fit tool LRT-12-034 to valve and tighten screw

to compress valve spring sufficiently to release
collets from valve spring cap.

4. Remove 2 collets and release valve spring

compressor.

5. Remove valve spring cap and valve spring.
6. Remove valve from cylinder head.
7. Remove and discard valve stem oil seal.
8. Repeat above operations for remaining valves.
9. Keep valves, springs, caps and collets in their

fitted order.

Inspect

1. Clean mating faces of cylinder block and head

using suitable gasket removal spray and a
plastic scraper, ensure that bolt holes in block
are clean and dry.

CAUTION: Do not use a metal scraper or
machined surfaces may be damaged.

2. Clean cylinder head, valve springs, valves and

inlet valve guide bores. Ensure all loose
particles of carbon are removed on completion.

3. Check head and block faces for warping and

pitting. Maximum warp = 0.05 mm (0.002 in).

4. Check cylinder head height at each end of

head. Renew a head which is outside limits.

a 22.94 mm (0.903 in) - New

b 62.56 mm (2.463 in) - New

5. Cylinder head can be refaced to 0.50 mm (0.02

in) max. below head height.

ENGINE - V8

OVERHAUL 12-2-63

6. Remove carbon deposits from exhaust valve

guide using a 8.70 mm (0.34 in) diameter
reamer inserted from combustion face side of
cylinder head.

NOTE: Modified inlet valves, exhaust valves
and valve guides were fitted to 4.0 litre engines
from the following engine numbers: 55D
05678A; 56D 50788A and 97D 05505A and are
fitted to all 4.6 litre engines.

7. Modified inlet valves may be identified by

measuring the distance 'A' from the valve head
face to the top of the undercut on the valve
stem:

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Early valves = 29.5 to 30.5 mm (1.16 to 1.20
in)

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Later valves = 32.5 to 33.5 mm (1.28 to 1.32
in)

8. Modified exhaust valves may be identified as

follows:

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Early valves 'A' – Chrome finish

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Later valves 'B' – Black nitrided finish

9. Modified valve guides are 5 mm (0.211 in)

shorter than the early type, the overall length is
now 57 mm (2.24 in); the reduction in length
being the distance the guide protrudes into the
combustion chamber side of the cylinder head.

NOTE: The modified valves and guides may be
fitted to 4.0 litre engines prior to the above
numbers in cylinder sets. Early type valves will
continue to be supplied for early 4.0 litre
engines but if valve guides are found to be
worn, the later valves and guides must be fitted.

ENGINE - V8

12-2-64 OVERHAUL

10. 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)

11. 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).

12. 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).

13. Check valve stem to guide clearance using the

following procedures:

14. Insert each valve into its respective guide.
15. Extend valve head approximately 13 mm (0.6

in) out of valve seat and position a DTI gauge
to rear of valve head.

16. Move valve towards front of cylinder head and

zero DTI gauge ensuring that stylus of gauge
remains in contact with valve head.

17. 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).

18. Renew valve guides as necessary.

19. Using valve guide remover tool LRT-12-037

press valve guide into combustion face side of
cylinder head.