A standard Series Land Rover engine is not known for its high power output, so valve timing is crucial to getting the best performance possible. However, that does not mean that measuring and adjusting the valve clearances should become an obsession. It should also be borne in mind that a slight clicking sound should be heard from the rocker assembly as the engine ticks over - otherwise the clearances are too small or even non-existent. It is loud and probably irregular clicking from one or more valves that signifies that some checking and adjustment is required.
If a valve clearance is too large then the valve will open late and close early. There will then be louder clicking than normal and engine performance will be reduced. If a valve clearance is too little then the valve will open early and close late and there will NOT be a loud clicking sound. The early opening and late closing of valves with insufficient clearance, causes loss of compression and can cause valve seats to overheat and burn. If there is a gradual reduction of valve clearances over time then it could be a sign that the valve seats are burning off, due to running at hight revs on low octane fuel or, alternatively, unleaded petrol is being used in a cylinder head that has not had the valve seats converted for this fuel. Valve clearances should be checked annually or every 12,000 miles.
The rule of 9
(4cyl engines); rule of 13 (6 cyl engine)
Standard practise is to number the valves from the radiator. Turn the engine in the normal direction of rotation (a starter handle is useful here) and watch for when one valave is fully down. Note its number, sutract from 9 (or 13 for 6cyl engine) and that is the valve that can be chacked and adjusted if necessary. The procedure is to slacken off the locknut, turn the screw until the correct thickness feeler gauge is a close sliding fit between rocker and valve stem, then tighten the locknut whilst holding the adjusting screw in position with the screwdriver. Practise improves the technique and it is essential to re-check after the locknut has been tightened. As an aid to not setting the 0.010in clearance too wide, it is useful to have both the 0.010in and 0.012in feeler gauges open and to check that the latter cannot enter the valve clearance space at all. Also, make sure that the feeler gauge surfaces are clean and not having grit particles on them.
Series Land Rover Engine valve clearances
1595cc petrol Inlet 0.010in (0.25mm), exhaust 0.012in (0.30mm) hot or cold
1997cc petrol Inlet 0.010in (0.25mm), exhaust 0.012in (0.30mm) hot or cold
1997cc diesel Inlet & exhaust 0.010in (0.25mm) hot or cold
2286cc petrol Inlet & exhaust 0.010in (0.25mm) hot or cold
2286cc diesel Inlet & exhaust 0.010in (0.25mm) hot or cold
2625cc petrol Inlet 0.006in (0.15mm), exhaust 0.010in (0.25mm) hot
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