Cylinder head - overhaul (page 2 of 2)

Make

Land Rover

Model

Discovery II (UK)

Section

Overhaul

Engine - V8Cylinder head - overhaul · page 2 of 2

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: 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)
8. Modified exhaust valves may be identified as follows: l Early valves 'A' – Chrome finish l 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.

10 Engine