Occasionally check the condition of the battery by taking hydrometer readings of the specific gravity of the electrolyte in each of the c-ells. Readings should not be taken immediately after "topping up" the cells. The specific gravity readings and their indications are as follows:
1.280-1.300 (260 Baumé) Battery fully charged.
About 1.210 (220 Baumé) Battery about half discharged.
Below 1.150 (18 Baumé) Battery fully discharged.

These figures are given assuming the temperature of the solution is (30 degrees F. (15.5 degrees C). If the electrolyte temperature exceeds this, .002 must be added to hydrometer readings for each 5 degrees F (3 degrees C) rise to give the true specific gravity at 60 degrees F (15.5 degrees C). Similarly .002 must be subtracted from hydrometer readings for every 5 degrees F (3 degrees C) below 60 degrees F (15.5 degrees C).

The readings for all cells should be approximately the same. If one cell gives a reading very differently from the rest, it may be that acid has been spilled or has leaked from this particular cell or there may be a short circuit between the plates. In this case the battery should be examined by a Lucas Service Depot or Agent.

Never leave the battery in a discharged condition for any length of time. Have it fully charged and every fortnight give it a short refreshing charge to prevent any tendency for the plates to become permanently sulphated.


The dynamo is of the compensated voltage control type and operates in conjunction with the regulator Unit which is housed along with the cut-out in the control box.
The regulator causes the dynamo to give an output which varies according to the load on the battery and its state of charge. When the battery is discharged, the dynamo gives a high output so that the Battery receives a quick recharge which brings it back to its normal state in the minimum possible time.

Fig. 35. Taking Hydrometer

On the other hand, if the battery is fully charged, the dynamo is arranged to give only a trickle charge which is sufficient to keep it in good condition without any possibility of causing damage to the battery by overcharging.

The regulator also causes the dynamo to give a controlled boosting charge at the beginning of a run which quickly restores to the battery the energy taken from it when starting. After about 30 minutes running, the output of the dynamo falls to a steady rate, best suited to the particular state of charge of the battery.
Many years of experience with this type of dynamo have shown. that normally the brush gear and commutator will not require any attention by the owner. When the car is undergoing a general overhaul, say after about 50,000 miles (80.000 Km.), it is advisable to have the dynamo checked for brush or commutator wear by a Lucas Service Depot or Agent.

Occasionally inspect the dynamo driving belt and adjust if necessary to take up any undue slackness - by turning the dynamo on its mounting (see page 65). Care should be taken to avoid overtightening the belt and to see that the machine is properly aligned, otherwise undue strain will be thrown on the dynamo bearings.

Ammeter Readings.
When noting ammeter readings, it must be remembered that during daytime running when the battery is in good condition, the dynamo gives only a trickle charge so that the charge reading will seldom be more than three or four amperes.

A discharge reading may be given immediately after switching on the headlamps. This usually happens after a long run, when the voltage of the battery is high. After a short time, the battery voltage will fall, and the regulator will respond, causing the dynamo output to balance the load.

When starting from cold, the charging current will rise until it reaches a steady maximum at a speed of say, 2Q m.p.h. (35 k.p.h.) after which it will remain fairly high for about 10 minutes and then fall to a steady charge which is most suitable for the particular state of charge of the battery.

It will be noticed from the ammeter readings that the dynamo does not charge at very low engine speeds. This t~ because it is not rotating fast enough to generate sufficient energy to charge the battery. The cut-out which is an automatic switch connected between the dynamo and the battery allows the flow of current from the dynamo to the battery only. It closes when the dynamo is running fast enough to charge the battery and opens when the speed is low or the engine is stationary, thus preventing current flowing from the battery through the dynamo windings.

Fig 36 Control Box

This unit is mounted on the scuttle under the left-hand bonnet top panel and houses the cut-out, dynamo voltage regulator and two fuses, which protect the circuits of the auxiliary accessories.
The fuses are accessible without removing the cover protecting the regulator and cut-out.

The cut-out and regulator are accurately set before leaving the works and they must not be tampered with. The cover protecting them is sealed.

Fuse marked "AUX". This fuse protects the accessories which are connected so that they operate irrespective of whether the ignition is on or off.

Fuse marked "AUX IGN". This fuse protects the accessories which are connected so that they operate only when the ignition is switched on.

A blown fuse is indicated by the failure of all the units protected by it, and is confirmed by examination of the fuse, which can easily be withdrawn from the spring clips in which it fits. If it has blown, the broken ends of the wire will be visible inside the glass tube.

Before replacing a blown fuse, inspect the wiring of the units that have failed for evidence of a short circuit or other fault which may have caused the fuse to blow and remedy the cause of the trouble.
Spare fuses are provided and it is important to use only the correct replacement fuses. The fusing value is marked on a coloured paper slip inside the glass tube of the fuse.

Fig. 37. A Blown Fuse

If the new fuse blows immediately and the cause of the trouble cannot be found, have the equipment examined at a Lucas Service Depot.

When starting, observe the following points -.

1. See that the controls are properly set. (See Page 16).
2. Operate the starter switch firmly and release it as soon as the engine fires.
3. Do not operate the starter when the engine is running. If the engine will not fire at once, allow it to come to rest before operating the switch again. (See Page 17).

Do not run the battery down by keeping the starter on when the engine will not start.
In the event of the starter pinion becoming jammed in mesh with the flywheel, it can usually be freed by turning the starter armature by means of a spanner applied to the shaft extension at the commutator end. This is accessible by pulling off the small gap which is secured by two screws.

As in the case of the dynamo, the starter brush gear and commutator will not normally require attention by the owner but should be checked by a Lucas Service Depot or Agent when the car is undergoing a general overhaul.

Replacement of bulbs.
Lucas Genuine Spare Bulbs are sold by any reputable garage and are specially tested to ensure that the filament is in the correct position to give the best results with Lucas Lamps. To assist in identification Lucas Bulbs are marked on the metal cap with a number. When fitting a replacement see that it is the same number as the original bulb.
It is advisable to replace bulbs after long service before they actually burn out, as often the filament may sag.

Replacement Bulbs: Lucus Volt Watt Type

Headlamp (Home models) RH. No. 23 12 48 Single pole
  No. 54 12 36 Single pole
Headlamp (Home models) LH. No. 171 12 36 Double filament
Headlamps (Export models) No. 171 12 36 Double filament
Foglight No. 192 12 48 Single pole
Sidelamps No. 207 12 6 Single pole
Stop and tail lamps No. 189 12 24/6 Double filament
Reverse lamps No. 199 12 24 Single pole
Rear number plate lamps No. 989 12 6 Single pole
Instrument panel lights No. 207 12 6 Single pole
Interior (roof) light No. 207 12 6 Single pole
Ignition and mixture control warning lights No. 970 2.5 5 M.E.S.
Traflicators No. 256 12 3 Festoon

The lamps should be set as shown; check them by placing the car in front of a blank wall at the greatest possible distance taking care that the surface on which the car is standing is not sloping relative to the wall.

Export models are fitted with dual-filament bulbs in both lamps and Home models with a dual-filament bulb in the left-hand 'side only.

The headlamps must be set so that the main beams of light are parallel with the road and with each other. If adjustment is necessary, slacken the fixing nut at the base of the lamp and move the lamp on its adjustable mounting to the required position. Finally tighten the locking nut.

Foglight. (Home models).
The lamp must be set so that the beam does not rise above the horizontal when the car is standing on level ground. To ensure this, dip the lamp very slightly to compensate for road inequalities, and also tilt the lamp to the right to allow for road camber. In addition the lamp can be swung slightly to the left to give additional illumination on the left-band side of the road. If adjustment is necessary slacken the single fixing nut and move the lamp on its adjustable mounting to the required position. Finally tighten the locking nut.

Foglight (Export models).
The lamp must be set so that the beam does not rise above the horizontal when the car is standing on level ground. To ensure this, dip the lamp, very slightly to compensate for road inequalities and also tilt the lamp to the left or right to allow for road camber.

If adjustment is necessary slacken the 'single fixing nut and move the lamp on its adjustable mounting to the required position. Finally tighten the locking nut.

Fig. 38. Lamp Setting.
To enable the best light to be obtained from the headlamps the bulb filaments must be as near as possible to the focal points of the reflectors. If a bulb is out of focus, the lamps will have a poor range and will cause dazzle to approaching traffic. Before lamps leave the Works, the bulbs are focused to give the best results and provided that Lucas Genuine Spare bulbs are fitted as replacements, it should not be necessary to alter the setting. If, however, an ordinary bulb has to be fitted, it may he necessary to re-focus by slackening the screw on the clamping clip and moving the bulb backwards and forwards until the best lighting s obtained.

When focusing, it is an advantage to cover one lamp while testing the other. If the lamp does not give a uniform long range beam without a dark centre, the bulb needs adjusting. Tighten the clamping clip after the best position for the bulb has been found.
The foglight is fitted with a pre-focus bulb which is accurately positioned in relation to the reflector and no focusing is required when a replacement bulb is fitted.

Fig. 39. Lamp Focusing


To remove the lamp front bottom of the lamp pull forward the fixing clip at the and swing it downwards. Remove the front from the bottom of the lamp first. The reflector is secured to the lamp body by means of a rubber bead and can be withdrawn when this is removed. When replacing fit the rubber bead over the rim of the reflector and the edge of the lamp body so that the thinner lip of the bead is in the groove at the front of the lamp body. When refitting the lamp front, locate the top of the rim first, then press at the bottom and secure by the clip.

Fig. 40 Removing
Headlamp Reflector
This lamp incorporates a Lucas Light Unit which consists essentially of a combined reflector and front rim assembly. The bulb is correctly positioned in relation to the reflector and no focusing is required when a replacement bulb is fitted. To fit a replacement bulb unscrew the single securing screw at the bottom of the lamp rim which is split to facilitate removal, and remove the Rim and Light Unit Assembly. The bulb can be removed from the back of the Light Unit when the spring clips attached to the bulb are pressed inwards.

Fig. 41 PassLight (Home models) or Foglight (Export models)

Fix the spring clip to the replacement bulb and place the bulb in the holder taking care that the marking "TOP" is uppermost'
When replacing the Light Unit, the metal tongue on the inside must be engaged with the slot in the lamp body. Finally secure the rim by tightening the fixing screw.

To detach the front for bulb replacement, remove the screw at the back of the lamp; the bulb is then, accessible.

Rear Number Plate Lamps.
To remove the cover for bulb replacement, slacken the securing screws and swing open the, cover; 'the bulbs are then accessible in the lamp body.

Cleaning Lamps.
The reflectors are protected by a transparent and colourless covering which enables any accidental finger marks to be removed with chamois leather or a soft cloth without affecting the surface of the reflector. Metal polishes must not be used for cleaning reflectors or chromium-plated lamp bodies. The lamp bodies must be -washed in plenty of water and when the dirt is completely removed they must be polished with a chamois leather or a soft dry cloth.

For operation see Page 15.
Replacement of Bulb.
Withdraw the screw on the underside of the arm and slide off the metal plate; the burnt-out bulb may then be renewed. To replace the metal plate, slide it on in an upwards direction so that the side plates engage with the slots on the underside of the spindle bearing. Finally secure the plate by means of its fixing screw.

All horns before being passed out of the Works are adjusted to give their best performance and will give a long period of service without any attention; no subsequent adjustment is required.

If one of the horns fails or becomes uncertain in not follow that the horn has broken its action, it does down. First ascertain that the trouble is not due to some outside source, e.g., a loose connection or short circuit in the wiring of the horn. If both horns fail or become uncertain in action, the trouble is probably due to a discharged battery or blown fuse. If the fuse has blown, examine the wiring for the -fault and then replace the fuse.

It is also possible that the performance of a horn may be upset by the fixing bolt working loose, or by some component near the horn being loose. If after carrying out the above examination the trouble is not rectified, the horn may need adjustment, but this should not be necessary until the horns have been in service for a long period.

NOTE: Adjustment merely takes up wear of moving parts-it does not alter the pitch of the note.
When making adjustments, disconnect one horn, ensuring that the end of the cable does not come into contact with any part of the engine or chassis. It is also advisable to short circuit the fuse during this operation. If while adjusting, the horn does not operate release the push immediately.

Fig. 42. Horn Adjustment

Remove the horn cover after withdrawing the fixing screw and detach the cover securing bracket by springing it from its fixing.
Slacken the lock-nut on the fixed contact and rotate the adjusting nut until the contacts are just separated (indicated by horn failing to sound). Turn the adjusting nut half a turn in the opposite direction and secure in this position by tightening the lock-nut.

Finally, if the note is still unsatisfactory do not dismantle the horn but return it to a Lucas Service Depot or Service Agent for examination.

To start the wipers it is only necessary to move the switch to the "ON" position. Parking of the arms is effected by switching off at the end of the stroke.

Renewing the High Tension Cables.
The high tension cables are those connecting the coil to the distributor and the~ distributor to the sparking plugs. - When these cables show signs of perishing or cracking they must be replaced by 7 m.m. rubber-covered ignition cable.

The method of connecting H.T. cable, to the coil is to thread the knurled moulded nut over the cable, bare the end of the cable for about 0.25 in. (7 mm.), thread the wire through the washer removed from the end of the original cable and bend back the wire strands. Screw the nut into its terminal.

Fig. 48. Connecting H.T. Cable
To connect cables to the distributor, unscrew the pointed fixing screws on the inside of the moulding and push the cables, which should not be bared but cut off flush to the required length, well home into their respective terminals. The screw securing the centre cable is accessible when the carbon brush is removed.

On some early models the high tension cables to the distributor are held by a moulded cover secured by screws. The cables, which should be cut off flush, are located in recesses in the distributor moulding and are pressed on to pointed terminal studs which pierce the insulation to make good contact with the core.

The Coil.
The coil requires no attention beyond keeping its exterior clean, particularly between the terminals and occasionally checking that the terminal connections are quite tight.

The Ignition Switch and Warning Light.
The ignition switch, besides forming a means of stopping the engine, is provided for the purpose of preventing the battery being discharged by the current flowing through the coil windings when the engine is stopped. A red warning light on the instrument panel appears when the ignition is switched on and the engine is running very slowly or is stationary.

Should the warning lamp bulb burn out, this will not in any way affect the ignition system, but it should be replaced as soon as possible in order to safeguard the battery.

Mixture Control Warning Light.
The amber mixture control warning light on the instrument panel appears when the engine reaches normal working temperature, indicating that the "COLD START" control should be pushed right in to the normal running position.

If the warning lamp bulb burns out, it will not affect the operation of the mixture control, but it should be replaced as soon as possible to ensure that the control is pushed "home" at the earliest possible moment, and so safeguard against unconscious driving with the mixture control in an intermediate position, with consequent high petrol consumption and dilution of the engine oil.