Discovery 2. Manual — part 443

ENGINE - V8

OVERHAUL 12-2-65

20. 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.

21. 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).

22. Ream valve guide to 8.70 mm (0.342 in).
23. Position cylinder head stands and mount

cylinder head on stands.

24. 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.

25. Remove worn valve seat.

CAUTION: Take care not to damage the
counterbore in the cylinder head when
removing valve seats.

26. Heat cylinder head evenly to approximately

120

°

C (250

°

F).

WARNING: Handle the hot cylinder head
with care.

27. Using a suitable mandrel, press new insert fully

into counterbore.

28. Allow cylinder head to air cool.

CAUTION: Renew worn valve guides and/or
valve seats before lapping the valves.

29. Recut valve seat in head and lap in valves

using fine paste.

30. Coat valve with a small quantity of engineer's

blue, insert valve and press into position
several times without rotating. Seating position
should be in centre of valve face.

ENGINE - V8

12-2-66 OVERHAUL

31. Check valve installed height if valve seats have

been refaced or renewed.

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Valve installed height, end of valve to base
of spring seat, 'A' = 44.16 to 45.29 mm (1.74
to 1.80 in).

32. Reface valves as necessary. If a valve has to

be ground to a knife-edge to obtain a true seat,
renew valve.

33. Cut valve seats using suitable cutters:

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Valve seat angle 'A' = 45

°

.

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Valve seat insert diameter 'B' Inlet = 36.83
mm (1.45 in).

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Valve seat insert diameter 'B' Exhaust =
31.50 mm (1.24 in).

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Seating width 'C' - Inlet = 0.89 to 1.4 mm
(0.035 to 0.055 in).

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Seating width 'C' - Exhaust = 1.32 to 1.83
mm (0.052 to 0.072 in).

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Angle 'D' = 70

°

.

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Angle 'E' = 46

°

to 46

°

25'.

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Angle 'F' = 20

°

.

34. Check that cutter blades are adjusted so that

middle of blade contacts area of material to be
cut. Use light pressure and only remove the
minimum of material necessary.

35. Clean valve seat and valve.

Reassembly

1. Clean spring caps, collets and valve springs.
2. Lubricate new valve stem oil seal with clean

engine oil and fit seal.

3. Lubricate valve with clean engine oil and fit

valve.

4. Fit spring and cap, compress spring using tool

LRT-12-034 and fit collets.

5. Release valve spring and remove tool LRT-12-

034.

6. Fit cylinder head gasket.

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ENGINE - V8, OVERHAUL, Gasket -

cylinder head.

ENGINE - V8

OVERHAUL 12-2-67

Piston assemblies

$% 12.17.02.01

Disassembly

1. Remove cylinder head.

+

ENGINE - V8, OVERHAUL, Gasket -

cylinder head.

2. Remove oil pick-up strainer

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ENGINE - V8, OVERHAUL, Strainer

- oil pick-up.

3. Suitably identify each connecting rod and

piston assembly to its respective cylinder bore.

4. Remove 2 bolts securing each connecting rod

bearing cap.

5. Remove connecting rod bearing cap and

collect connecting rod bearings.

6. Remove ridge of carbon from top of cylinder

bores.

7. Carefully push each piston assembly from the

top of the cylinder.

CAUTION: Ensure that connecting rods do
not contact cylinder bores.

8. Refit bearing cap onto connecting rod, lightly

tighten dowel bolts.

9. Suitably identify each piston to its respective

connecting rod.

10. Position body of tool LRT-12-013 in vice.
11. Screw large nut back until flush with end of

centre screw.

12. Push centre screw forward until nut contacts

thrust race.

13. Fit piston adapter tool LRT-12-126/2 .
14. Position guide pin tool LRT-12-126/3 in LRT-

12-126/2 with groove facing away from piston.

15. Locate piston and connecting rod assembly on

centre screw and up to adapter tool LRT-12-
126/2.

16. Fit remover/replacer bush tool LRT-12-126/1

on centre screw with flanged end facing away
from gudgeon pin.

17. Screw stop nut onto centre screw leaving

clearance of 3 mm (0.125 in), dimension 'A',
between nut and remover/replacer bush.

18. Lock the stop nut securely with lock screw.
19. Push connecting rod to locate end of gudgeon

pin in adapter tool LRT-12-126/2.

20. Ensure remover/replacer is located in gudgeon

pin bore of piston.

21. Screw large nut up to tool LRT-12-013.
22. Hold lock nut and turn large nut until gudgeon

pin is withdrawn from piston.

23. Dismantle tool and remove piston, connecting

rod and gudgeon pin.

ENGINE - V8

12-2-68 OVERHAUL

Inspect

1. Clean carbon from piston. Inspect piston for

distortion, cracks and burning.

2. Remove piston rings from piston.

3. Measure and record piston diameter at 90

°

to

gudgeon pin axis and 10 mm (0.4 in) from
bottom of the skirt. The piston must be 0.02 to
0.045 mm (0.001 to 0.002 in) smaller than the
cylinder bore.

4. Check gudgeon pin bore in piston for signs of

wear and overheating.

5. Pistons fitted on production are graded 'A' or

'B', the grade letter is stamped on the piston
crown.

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Piston diameter: Grade 'A' = 93.970 to
93.985 mm (3.6996 to 3.7002 in).

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Piston diameter: Grade 'B' = 93.986 to 94.00
mm (3.7002 to 3.7007 in).

6. Worn cylinders fitted with grade 'A' pistons may

be honed to accept the grade 'B' piston
provided that specified cylinder bore and
ovality limits are maintained. Grade 'B'
pistons are supplied as service
replacements. Do not attempt to de-glaze
cylinder bores.

7. Check gudgeon pins for signs of wear and

overheating.

8. Check clearance of gudgeon pin in piston.

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Gudgeon pin to piston clearance = 0.006 to
0.015 mm (0.0002 to 0.0006 in).

9. Check overall dimensions of gudgeon pin.

Gudgeon pins are only supplied as an
assembly with replacement pistons.

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Gudgeon pin length = 60.00 to 60.50 mm
(2.362 to 2.382 in).

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Gudgeon pin diameter = 23.995 to 24.00
mm (0.9446 to 0.9448 in)

10. Measure cylinder bore wear and ovality in two

axis 40 to 50 mm (1.6 to 2 in) from top of bore.
The temperature of piston and cylinder
block must be the same to ensure accurate
measurement. Do not attempt to de-glaze
cylinder bores.

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Grade 'A' pistons: Cylinder bore = 94.00 to
94.015 mm (3.7007 to 3.7013 in).

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Grade 'B' pistons: Cylinder bore = 94.016 to
94.030 mm (3.7014 to 3.7019 in).

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Maximum ovality = 0.013 mm (0.0005 in).

11. Check alignment of connecting rods.

Reassembly

1. Pistons have a 5 mm (0.2 in) offset gudgeon pin

which can be identified by an arrow mark on
the piston crown. This arrow must always point
towards the front of the engine.

2. Assemble pistons to connecting rods with

arrow on piston pointing towards domed
shaped boss on connecting rod for RH bank of
cylinders and arrow pointing away from domed
shaped boss for LH bank of cylinders.