OCTANE SELECTOR.
The timing of the ignition is controlled automatically by mechanism in the distributor. In addition, an octane selector is fitted. This is a vernier adjustment attached to the distributor (Fig. 7) fitted with a sliding portion controlled by an adjusting screw and a calibrated scale marked R (retard) and A (advance) with a number of divisions between. The standard setting for the ignition is with the long line of the scale on the sliding portion against the mark on the selector body, thus leaving one division further possible advance and four divisions retard.
This setting is correct for 75 octane fuel and with a clean engine, but should pinking develop as a result of the need for decarbonising, the control can be retarded a little by turning the screw in an anti-clockwise direction. Do not forget to return it to the original position after decarbonising.
In certain countries very low grade fuel is supplied, in which case it may be necessary to adjust the octane selector to avoid pinking, even with a clean engine.

FLYWHEEL MARKINGS.
The flywheel markings and timing pointer are visible when the inspection cover on the right-hand side of the flywheel housing is removed. (Fig. 6).
The markings and their meanings are as follows -
(1) The line against which the letters T.D .C. are stamped, when brought dead opposite the pointer, means that No. 1 piston is on Top Dead Centre, i.e., at the top of its stroke.
(2) The line against which the letters F.A. 15o are stamped, when set opposite the pointer, indicates the firing-point of No. 1 cylinder when the octane selector is set in the standard position on the sliding scale (i.e., the point at which the distributor points should be just opening, with the rotor in the firing position for No. 1 or No. 4 cylinder). It is 15o before T.D.C. (4 flywheel teeth). Disregard the other F.A. marks at 7o,8o, and 11o on certain flywheels.
(3) The line against which the letters E.P. are stamped, when set opposite the pointer, indicates the point at which No. 1 exhaust valve should be at the peak of its lift (fully open). It is 114o before T.D.C. (31 flywheel teeth).

VALVE TIMING.
If the timing chain and hydraulic tensioner should have been removed, the procedure to re-time the engine is as follows. (See Fig. 11).
(1) Set the exhaust tappets as Instructed on Page 38 and slacken the inlet tappet adjusting screws as far as possible.
(2) Rotate the camshaft in the running direction until No. 1 exhaust valve is fully open.
The use of a dial indicator is the only reliable method of determining this point. It should be mounted on a stud adjacent to No. 1 exhaust rocker and with its aid the possibility of an error in determining the exhaust peak is eliminated. It is possible to do the job correctly without a dial indicator, but much time is wasted and the possibilities of an error very much magnified.
(3) Rotate the engine in the running direction until the E.P. mark on the flywheel is in line with the pointer.
(4) Fit the timing chain, ensuring that there is no slack on the driving side (G).
(5) Hold the ratchet pawl (E) clear and replace the complete pulley (C, F and H), meshing the pulley with the chain.
(6) Check the timing and correct if necessary. The camshaft chainwheel (A) is made with three irregularly spaced keyways, so that if the timing will not come correct in the first position tried, alternatives are provided.
(7) Replace the hydraulic tensioner (D), comprising cylinder, piston and spring; these items must be assembled dry to prevent the formation of an air lock. Retain at its upper end with a split pin. Fit the circlip at (H), retaining the jockey pulley assembly. Engage the ratchet (E, F).
(8) Set the inlet tappets as instructed below.

Fig. 11. Timing gears

A: Camshaft chainwheel
B: Crankshaft chainwheel
C: Jockey pulley
D: Hydraulic tensioner
E: Pawl
F: Ratchet
G: Timing chain
H: Jockey pulley arm

IGNITION TIMING.
(1) Check the contact breaker clearance and adjust if necessary, using the combined feeler gauge and screwdriver supplied in the tool kit. The correct gap with the points fully open is .012 in. (0,30 mm.).
(2) Rotate the engine in the running direction until the FA150 mark on the flywheel is in line with the pointer, with both valves on No. 1 cylinder closed.
(3) The rotor of the distributor will now correspond with No. 1 cylinder high tension lead terminal.
(4) Set the octane selector to the standard position on the sliding scale.
(5) Set the distributor points just breaking by slackening the j in. pinch bolt at the base of the distributor head and rotate the distributor bodily in the required direction. Do not forget to re-tighten the pinch bolt.

TAPPET ADJUSTMENT.
The firing order is 1, 3, 4, 2. The correct tappet clearance is .010 in. (0,25 nim.) on the inlet valves and .012 in. (0,30 mm.) on the exhaust valves, with the engine either cold or at running temperature. Adjustment for this clearance is provided by a set-screw and lock-nut on the rocker. (See Figs. 12 and 13). When adjustment is required, slacken the lock-nut and rotate the set-screw to give the correct clearance by means of a screwdriver. The lock-nut should be securely tightened after adjustment, great care being taken to ensure that this operation does not upset the clearance.

Fig. 12. Inlet tappet adjustment.

Fig. 13. Exhaust tappet adjustment.

A-Tappet adjusting screw.
B-Lock-nut.
C-Feeler gauge.

The tappet clearance should be set with the engine either cold or at running temperature and it is essential to ensure that the valve to be adjusted is really closed. To do this, set the valve receiving attention fully open and then move the engine one complete turn to bring the tappet on to the back of the cam. It cannot be urged too strongly that the clearance must be correct if the best results are to be obtained.

SPARKING PLUGS

Lodge HLNR sparking plugs are fitted as standard equipment. Every 3,000 miles (5.000 Km.) or 100 hours, the plugs should be removed and cleaned and the electrode gaps re-set to .023-.026 in. (0,60-0,65 mm.) if necessary.

CLUTCH

The clutch should be used purely for starting the car from rest and when changing gear. It is bad driving and detrimental to any clutch to " coast hills with the clutch pedal depressed, or to make a habit of slipping the clutch when rounding corners, etc.
The clutch pedal adjustment is correct when there is 0.75 in. (20 mm.) free movement measured at the pedal pad and the linkage should be re-set when the movement falls below this 'figure. Adjustment is provided by a nut on the end of the rod connecting the pedal to the clutch operating lever on the bellhousing; this nut is machined so that it locks itself at every half turn against the joint-pin in the pedal lever. To increase the tree pedal travel, turn the nut in an anti-clockwise direction half a turn at a time and make sure that the nut is against the pin, before checking the pedal movement. (Fig. 14).

Fig. 14. clutch adjustment.

A-Clutch adjustment nut.
B-Clutch pedal shaft.
C-Brake master cylinder.
D-Brake pedal shaft.
E-Stop light actuating spring.
F-Brake pull-off spring.

COOLING SYSTEM

The system is designed to give very efficient cooling under all operating conditions, provided that the service attentions listed on Page 43 are carried out at regular intervals.

RADIATOR.
The radiator, which is constructed with cooling gills of a special design, is cooled to shroud the four-bladed fan mounted on the water pump spindle. Evaporation and consequent loss of coolant when operating at high temperature is prevented by pressurisation of the system by means of a sealed type filler cap. The cap incorporates a relief valve which opens and allows steam to escape at a pre-determined pressure; by this means the boiling-point of the coolant is raised appreciably above the normal 1OOC. (212F.). It is most unlikely that such a high temperature would be reached under the most exacting conditions and even if it were, the relief valve permits the engine to be kept running without risk of damage. A vacuum valve is also fitted to the filler cap to relieve the depression resulting when the engine has cooled down after running at extremely high temperatures.

Fig. 15. Radiator filler cap.

A-Pressure relief valve (steam escape)
B-Depression relief valve

The standard radiator cap incorporates a relief valve which opens at approximately 5 lb. per sq. in. (0,35 Kg/cm2.). A special cap is available as an item of extra equipment for use when the vehicle is employed under very hot conditions or for prolonged periods of stationary work the relief valve in this pattern opens at approximately 15 lb. per sq. in. (1,05 Kg/cm2.).
When removing the filler cap, first turn it anti-clockwise to the stop and allow all pressure to escape before pressing it down and turning further in the same direction to lift it off.
The radiator block drain tap is situated at the bottom on the right-hand side.

WATER PUMP.
The centrifugal pattern water pump is designed to give maximum service between overhauls and no adjustment is provided or necessary. It is mounted on the front of the cylinder block and, together with the fan, is driven by a pulley and "V" type belt from the crankshaft. (The belt also drives the dynamo). The sealed double-row ball bearing, integral with the pump spindle, is pre-packed with high melting point grease and requires no further lubrication throughout its life.

THERMOSTAT.
The thermostat is fitted in the housing at the front of the cylinder head above the water pump casing, to which it is con nected by a tube and rubber joint ring. Its purpose is to provide rapid warming-up by causing the coolant to circulate only round the engine until a pre-determined temperature is reached, when it opens to allow full circulation through the radiator. The unit operates at 167-190F. (75-88C.) and this setting cannot be altered in any way.
If overheating of the engine should occur, check that the thermostat is functioning correctly; to do this, remove the thermostat from its housing and run the engine ; if the overheating is eliminated the unit is faulty and must be replaced.

FAN BELT.
As the belt is of the "V,' type, the drive is on the sides of the belt and it is not therefore necessary to adjust it tightly and so put an excessive load on the water pump and dynamo bearings. The tension is correct when it is possible to depress the belt by thumb pressure approximately 0.5 in. to 1 in. (12 mm. to 25 mm.), at a point midway between the fan and crankshaft pulleys.
Adjustment of the belt tension is provided by slackening off the two nuts on the dynamo pivot bolts and the set-bolt retaining the adjusting link to the dynamo, moving the dynamo outwards until the setting is correct and re-tightening the nuts and set-bolt.

DRAINING THE COOLING SYSTEM.
The cooling system should be flushed out at least twice each year. It can be completely drained by opening the taps on the radiator block and on the right-hand side of the cylinder block at the rear; remove the radiator filler cap to prevent a vacuum which may impede thorough draining. When the water has ceased to flow, a piece of wire should be inserted in each tap to make sure that a blockage has not been caused by rust or scale from the system. Place a hose in the radiator filler neck and adjust the flow of water to equal that draining from the two taps; start the engine and allow it to run until the whole cooling system has been thoroughly washed out. Switch off the engine, close the taps, refill the radiator with clean water to the bottom of the filler neck and replace the filler cap. When filling, use soft water for preference (rain water will do), as this prevents to a great extent furring up of the inside of the radiator, cylinder jackets and pipes. The capacity of the system is 17 pints (9,5 litres).

CLEANING RADIATOR.
In the event of the cooling gills of the radiator becoming blocked with dirt, straw, etc., they should be cleaned by means of compressed air or water pressure applied from the rear, so forcing the foreign matter out through the front of the radiator. Never use a metal implement for this purpose or serious damage may result to the radiator core.

SERVICE ATTENTION.
It is a good plan to always inspect the cooling system at the same time as the engine oil level is checked, i.e., daily under normal conditions. This care would largely prevent the possibility of a sudden and costly delay due to coolant loss and consequent engine failure. The inspection need only take a few moments and should include the following points -
(i) Water level in radiator-should be to the bottom of the filler neck.
(ii) Condition of all water hoses-freedom from cracks and hose clips tight.
(iii) Fan belt tension-a loose belt will lower the efficiency of the pump and fan and cause overheating.
(iv) Check for water leaks.

FROST PRECAUTIONS.
In cold weather, when the temperature may drop below freezing point, precautions must be faken to prevent freezing of the water in the cooling system.
As a thermostat is fitted to the Land-Rover, it must be appreciated that it is possible for the radiator block to freeze when running in cold weather, even though the engine temperature is quite high; for this reason the use of an anti-freezing mixture is absolutely essential.
As some anti-freezing solutions have a corrosive effect upon the thermostat and other portions of the cooling system, we have found it necessary to recommend only pure ethylene glycol or good- glycol-base solutions such as "Bluecol"; for your own protection we advise you, wherever possible, to use nothing else.
Anti-freezing solutions are far more "searching" at joints than water; before using them in your Land-Rover, it is therefore important to ensure that the cooling system is leak-proof. If any doubt exists regarding the condition of hoses, etc., they should be replaced. The table below gives the percentage volume of Bluecol required to safeguard against temperatures down to 400F. (-40C.).

COOLANT STRENGTH

Above 32F. (0C.). 100% water. 17 pints (9,5 litres).
To 12F. (- 11C.) 86% water. 14% Bluecol. 14.5pints (8,0 litres). 2.5 pints (1,5 litres).
To -4 F. (-2OC.) 80% water. 20% Bluecol.18.5 pints (7,5 litres). 3.5 pints (2,0 litres)j.
To -20F. (-290C.) 76% water. 24% Bluecol. 13.0 pints (7,0 litres). 4.0 pints (2,5 litres).
To -40F. (-400C.) 70% water. 30% Bluecol. 11.75 pints (6,5 litres). 5.25 pints (3,0 litres).

The anti-freezing mixture should be well mixed to the required strength in a separate container and added after thoroughly flushing out the system (do not simply add the correct amount of glycol through the radiator filler); run the engine for a short while to assist good circulation.

It is important when the winter is over, that steps he taken not only to drain off the mixture, but to flush the system through several times with very hot soda water in order to remove all traces. Failure to take this precaution may eventually, after a season or two of neglect, lead to the complaint of boiling.

If the vehicle is to be stored in cold weather, unless it is kept in a well-heated garage or anti-freezing solution has been added to the coolant, the system must be completely drained as instructed under "DRAINING THE COOLING SYSTEM" above. After the water has drained out, it is well to run the engine at a fast idling speed for not more than half a minute, so as to dry out any water that may have been retained in the bottom of the jacketing.