Discovery II
ENGINE - V8
12-2-64 OVERHAUL
6. Cylinder head can be refaced to 0.50 mm (0.02
in) max. below head height.
7. 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.
8. 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:
l
Early valves = 29.5 to 30.5 mm (1.16 to 1.20
in)
l
Later valves = 32.5 to 33.5 mm (1.28 to 1.32
in)
9. Modified exhaust valves may be identified as
follows:
l
Early valves 'A' – Chrome finish
l
Later valves 'B' – Black nitrided finish
10. 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.
