HANDBOOK

FOR

25-30 H.P.
ROLLS-ROYCE CAR
CHASSIS SERIES
(In order of Issue)

GUL GRM GAN GRO GRP GAR

GYL GXM GWN GHO GMP GGR
GHL GGM GUN GMO GLP GZR

Liable to alteration without notice

PRICE £ 1. 5. 0

PUBLISHED BY

ROLLS-ROYCE, LIMITED

D ERBY , C REWE ,
AND AT 14 AND 15, C ONDUIT S TREET, L ONDON

CONDENSED EDITION
NO. XVII
 Front Brake
Front Axle Control Adjustment

Steering Pivot
Front Hydraulic
Damper
Cross Steering Tube ROLLS-ROYCE LIMITED.
Dynamo Side Steering Tube

Carburetter Air London Office and Showroom :

Carburetter Silencer 14 & 15, CONDUIT STREET, LONDON, W.
Steering Box
Crankcase Oil Filter Distribution Box and TELEGRAMS: “ROLHEAD REG. LONDON.”
Output Regulator TELEPHONES: MAYFAIR 6201 (7 lines)
Chassis Oil Pump Fuel Pumps CODES USED: A B C (5TH EDITION), BENTLEY’S, MARCONI
MOTOR TRADE, WESTERN UNION
Starter Motor Pinion Speedometer Drive
Housing
Accelerator Pedal
Clutch Pit Inspection Main Service Station:
Cover
Starter Switch Hythe Road, Willesden, London N.W. 10
Servo Motor
TELEGRAMS: “SILVAGOST, WESPHONE, LONDON”
Switch Box
TELEPHONE: LADBROKE 2444
Grouped Instruments Hand Brake Lever

Universal Joint
Gear Lever
Crewe Repair Depôt:
Foot Brake Equaliser Strangler Control Pym’s Lane, Crewe
TELEGRAMS: “ROYCRU, CREWE”
Brake Rods Ignition Control TELEPHONE: CREWE 3271 (10 LINES)

Throttle Control
Brake Ropes

Hand Brake Authorised Paris Service Station:

Equaliser
Spring Gaiter Franco-Britannic Autos Ltd.
Rear Hydraulic 25 Rue Paul Vaillant Couturier, Levallois, Seine
Damper
TELEGRAMS: “FRANCOBRIT-LEVALLOIS-PERRET-FRANCE”
Universal Joint
TELEPHONE: PERIERE 60-24
Battery

Rear Axle Filling

Plug Rear Brake
Adjustment
Fuel Tank Filler
Fuel Gauge Unit

Fig.1. - Plan View of Chassis.

 CONTENTS
PAGE
SERVICE FACILITIES fOR ROLLS-ROYCE CARS ... ... ... 4
THE
LEADING PARTICULARS OF CHASSIS ... ... ... ... 5
SECRET OF SUCCE S S F U L
CHAPTER I.- STARTING THE ENGINE AND DRIVING THE CAR 7
RUNNING. Starting the Engine - Ignition Control-Throttle Control-Change-
over Switch for Fuel Pump- Fuel Gauge-Gear Changing-Con-
trollable Shock Dampers-Lighting Control and Switch-Radiator
Shutters-Overheating-Fitting of Snow Chains.
Before a Rolls-Royce chassis is sold it is very
carefully tested and adjusted by experts. It will run best CHAPTER II.- PERIODIC LUBRICATION AND ATTENTION ... 13
if no attempt be made to unnecessarily interfere with Lubricants Recommended-Capacities-Centralised Chassis Lubri-
adjustments. cation System-Daily Maintenance-Every 2,000 miles-Tappet
Adjustment-Every 5,000 miles-Every 10,000 miles-Every
20,000 miles-Care of Wheels and Hubs-Replacement Tyres-
An owner would do well to instruct his driver as Balancing Road Wheels.
follows:-
CHAPTER III.- FUEL SYSTEM ... ... ... ... ... ... 30
Lubricate effectively, in strict accordance with the The Fuel System - Fuel Pumps - Petrol Filters - Action of the
advice given in this Handbook, and do not neglect any Carburetter-Accelerator Pump-Economiser Jet-Strangler Con-
trol for Starting - Adjustment of Carburetter-Setting of Idling
part. Adjustment-Diagnosis of Faults-Float Feed Mechanism-”Hot
Spot”-Air Silencer and Cleaner.
Inspect all parts regularly, but take care not to alter
any adjustments unless really necessary. CHAPTER VI.-ADJUSTMENT OF BRAKES ... ... ... ... 40
General-Adjustment of Foot Brakes-Adjustment of Hand Brakes
-Adjustment of Servo.

CHAPTER V.- THE CLUTCH ... ... ... ... ... ... ... 45
Adjustment of Clutch.

CHAPTER VI.- COOLANT SYSTEM ... ... ... ... ... 46

Coolant Pump-Radiator Shutters-CoolantLevel-Frost Pre-
Cautions-Fan.

CHAPTER VII.- ELECTRICAL SYSTEM ... ... ... ... ... 50

General-Battery-Battery Ignition-Sparking Plugs-Electrical
Fault Location

GUIDE TO MAIN SERVICE STATION ... ... ... ... ... 55

GIUDE TO CREWE SERVICE STATION ... ... ... ... ... 56

 SERVICE FACIL I T I E S
FOR ROLLS-ROYC E C A R S

Our interest in your Rolls-Royce car does not cease L E A D I N G PA RT I C U L A R S O F C H A S S I S .

w h e n y o u t a k e d e l i v e r y o f t h e c a r. I t i s o u r a m b i t i o n t h a t
every purchaser of a Rolls-Royce car shall continue to be Engine.
more than satisfied. Six cylinders, 3½” (89m/m.) bore, 4½” (114 m/m.) stroke, 4.257 c.c.,
29.4 H.P. on R.A.C. rating. Unit construction with gearbox, monobloc
Wi t h t h i s e n d i n v i e w, w e h a v e a p p a o i n t e d S p e c i a l with detachable head, overhead valves operated by pushrods, Rolls-
Retailers throughout the world, who have established Royce battery ignition with automatic advance, forced lubrication,
p r o p e r l y e q u i p p e d S e r v i c e S t a t i o n s , s t a ff e d b y m e n w h o h a v e cooling by pump circulation, down-draught carburetter.
been specially trained in servicing Rolls-Royce cars.
Electrica l E q u i p m e n t .
I n a d d i t i o n , o n t h e s t a ff o f R o l l s - R o y c e L i m i t e d , t h e r e Twelve-volt Rolls-Royce dynamo, starter motor, and other units.
are experts whose sole duty it is to maintain contact with Approximately 60 ampere-hour battery.
the Special Retailers, and they are available at all times to
b e c a l l e d i n f o r c o n s u l t a t i o n o n a n y m a t t e r s a ff e c t i n g y o u r
Clutch.
c a r.
Single dry plate.
If, therefore, you should require any assistance, Gearbox.
we ask that you should immediately contact our nearest Four-speed and reverse, side control; speedometer and brake servo-
S p e c i a l R e t a i l e r, w h o w i l l o n l y b e t o o p l e a s e d t o p l a c e h i s motor drives incorporated.
facilities at your disposal. If necessary he will call in for Rear Axl e .
consultation our expert in that area. It is earnestly hoped Hyphoid gears, full floating, rosd wheels entirely carried on axle
that this arrangement will prove of mutual benefit, as we tubes.
will thus be kept in constant touch with our Customers, who Br akes.
may be spared the trouble of a long journey to one of our Internal expanding, servo operated, on all four wheels. Independent
C o m p a n y ’s S e r v i c e S t a t i o n s . hand brake operating on rear wheels.
Road Spr i n g s .
In the event of it being more co n v e n i e n t t o c a l l o n u s Semi-elliptic, front and rear.
d i r e ct for assistance, o u r M a i n S e r v i c e S t a t i o n a t H y t h e W heels.
R o a d , Wi l l e s d e n , L o n d o n N . W. 1 0 , a n d t h e o n e a t o u r Wheels with 19” well-base rims and Dunlop C type tyres, size
factory at Crewe, will be ready at all times to help. (See 6.00-19 are fitted.
maps at end of Handbook.)
W heelbase. STARTING THE ENGINE AND DRIVING THE CAR 7
132”
CHAPTER I
Tr a ck .
56 5/16 ”
Starting the Engine and Driving the Car
Tu r n i n g C i r cles. Starting the Engine - Ignition Control-Throttle Control - Change -
Centre of outside front tyre:- over Switch for Fuel Pump - Fuel Gauge - Gear Changing-
R.H., 47’ 5” diameter; Controllable Shock Dampers - Lighting Control and Switch - Radiator
L.H., 42’ 0” diameter Shutters - Overheating - Fitting of Snow Chains.
O v e r w i n g s above centre line of front axle:- Starting the Engine.
R.H., 48’ 6” diameter; To start the engine, first check that the change gear lever is
L.H., 43’ 1” diameter in neutral, set thumb lever on instrument board to Start, switch on
the ignition by turning the right-hand thumb lever on the switchbox
F u e l Ta n k . to I.& C. - on later models to On- retard the ignition about one-
Eighteen gallons capacity, at rear of chassis. Supply by electric quarter from top of quadrant, and set hand throttle lever at bottom
pumps. of the quadrant. Now depress the starter button firmly and to its full
extent.
As soon as possible after the engine starts, set the hand throttle
C h a s s i s L u b r ication. lever a little over half-way up its quadrant and move thumb lever to
Centralised system, pedal-operated pump. Run. At the same time, advance ignition hand lever to the top of
its quadrant.
We i g h t . When making a start with a warm engine, leave thumb lever at
Chassis complete with tyres, battery, fuel, oil and water, but Run and set hand throttle lever a few notches up its quadrant and
ignition lever fully advanced.
excluding spare wheel, lamps and other accessories - approximately
The action of switching on the ignition also switches on the electric
2,930 lbs. fuel pumps, and a few pulsations of the latter may then be heard.
An appreciable pause must be made between the operations of switching
on the ignition and depressing the starter button, especially when making
a start from cold. This is necesary in order to give time for the pumps to
fill the float chamber of the carburetter.
A small red warning lamp on the instrument board will be illumi-
nated when the ignition is switched on, but will be extinguished when
the engine speed is sufficient to cause the cut-out contacts to close.
On no account should the accelerator pedal be “jiggled” when
using the starter motor-or indeed at any time. Such movement brings
into action the accelerator pump provided on the carburetter and
causes liquid fuel to be injected into the carburetter.
The thumb lever control on the instrument boardis arranged to
provide a suitably rich mixture for starting from cold, and it should
only be turned to Start under these conditions. Normally, it should
stand at Run. It is not intended for varying the mixture strength
under running conditions.
8 ROLLS-ROYCE 25-30 H.P. CAR STARTING THE ENGINE AND DRIVING THE CAR 9
It will be observed that when starting from cold the hand throttle Occasionally a few miles’ running should be done with the
lever is set in the closed position, i.e., at the bottom of its quadrant. The switch moved to “A” position, which cuts out one half of the pump.
reason for this is that there is an interconnection between the throttle lever At moderate throttle openings, no difference in running should be
on the carburetter and the instrument board thumb lever which causes noticeable. The test should then be repeated with the switch in the “B”
movement of the latter to Start, to open the throttle simultaneously the position, which cuts out the other half and switches on the half first cut
required amount. out.
As soon as the engine starts, the hand ignition control may be In the circumstances described, failure or defective running of the
fully advanced. engine only evident when the switch is on one side, indicates that one
When starting the engine for the first time in the day it is a good half of the pump is faulty, and Messrs Rolls-Royce Ltd., or one of their
plan to form the habit of depressing the chassis oil pump pedal once at Special Retailers, should be consulted at the earliest opportunity.
this stage. Subsequently it should be depressed once every 100 miles. If The connections of the change-over switch are shown in the
the car is to be driven only a few miles, however, half a pumpful will be Electrical Wiring Diagram, Fig. 23.
sufficient at the first starting. Fuel Gauge
When the engine is cold a high oil presure will be shown on the The electrical fuel gauge on the instrument board is graduated
gauge, due to the greater viscosity of the oil at low temperatures. The to register the total amount of fuel in the main tank. The gauge is
pressure will fall, however, as soon as the oil becomes warmer. inoperative when the ignition is switched off.
A starting handle is carried in the tool kit. In the event of it being Special contacts carried by the tank unit cause the green warning
used, it should be removed afterwards from the bracket and returned to lamp to light when only about two-and-a-half gallons of fuel remain in
the tool kit. The ignition must be fully retarded when starting by hand. the tank.
Gear Changing
Ignition Control. The position of the gear lever for each of the four speeds and
When driving the car, the ignition lever should normally be fully
advanced. The actual amount of advance is controlled partly by the reverse is shown in Fig.*2. When
reverse is required, the top of the
hand, as previously indicated, and partly automatically by means of lever must be depressed. This
a centrifugal governor operating on the distributor drive. This is releases a catch and enables the
capable of meeting 90 per cent. of the conditions due to varying road lever to be moved into the gate
speeds, leaving only extreme conditions to be met by moving the marked R.
hand control on the steering wheel. A special synchronising device
is provided in the gearbox to
Throttle Control. facilitate the changes between top
Under normal running conditions, the hand throttle control should and third gears and from second
be carried right back in the closed position. An adjustable stop is to third. All that it is possible to
provided on the carburetter for the throttle lever, which is so adjusted that ensure by such a synchronising
the engine will idle reliably in these circumstances when the accelerator mechanism, however, is that the
pedal is released. gear members to be engaged cannot
be brought together until they are
Change-over Switch for Fuel Pump. both rotating at the same speed.
In addition to the ordinary ignition switch, which also switches It does not sychronise the engine
on the pumps, a change-over switch is arranged on the instrument board and clutch shaft speeds. This must
in order to provide a ready means of checking that each half of the be done by the driver before re-
double fuel pump is operating correctly. engaging the clutch, otherwise
there will be an unpleasant jerk,
Normally, the switch would stand at Both when both halves of causing unnecessary wear and tear
the pump should be working. of the clutch and strain on the trans-
mission.
10 ROLLS-ROYCE 25-30 H.P. CAR STARTING THE ENGINE AND DRIVING THE CAR 11
It is necessary to depress the clutch pedal fully when changing I and C ... Ignition on, fuel gauge and fuel pumps on, and
gear. The gear lever should then be moved gently into the required connections closed to enable the dynamo to
gear position and, before re-engaging the clutch, the engine should charge the battery .
be speeded up when changing down, or allowed to slow down when On the later models a modified form of switchbox is provided
changing up, so that its speed shall suit the car speed on the required incorporating a master switch.
gear. The unit is carried on the right-hand end of the instrument board
Other changes, namely, those both up and down between second and includes:-
and first and that down from third to second, must be made in the usual (a) Master switch and lamp switch combined.
manner, double clutching when changing down. (b) Ignition switch.
Controllable Shock Dampers. (c) Push-button switch for starter motor.
In order to provide comfortable riding at all speeds, a centrifugally (d) Socket for inspection lamp plug.
-controlled pump is fitted which causes the damper loadings to increase (e) A lock which can be locked and the key withdrawn either:-
with the road speed. In addition, there is a lever above the steering (i.) When the master switch is in the “Off” position;
wheel, marked Riding Control, the effect of which is superimposed or (ii.) When the master switch is in the P.L. (“parking
on that of the governor. lights”)position;
For ordinary town work or touring with moderate speeds, it will No attempt must be made to lock the switch in other positions.
be found that the damper loadings as set by the governor are adequate With the master switch in the “off” position, most circuits and
when the hand lever is either at Soft or mid-way. On the other hand, accessories such as horns, starter motor, ignition, windscreen wiper,
at high speeds or with heavy loads, improved riding comfort will be instrument lamps etc., are rendered inoperative. Movement of this
obtained by moving the lever to Hard. master switch to the “on” position renders these accessories available.
Lighting Control and Switch The various combinations conrolled are clearly indicated as
Two types of switchbox are fitted, those on the earlier models follows:-
are as under:- OFF ... ... All circuits off, except for clock.
Carried on the right-hand end of the instrument board, this unit ON ... ... Accessories available
includes:- S and T ... Side and tail lamps on and accessories available.
(a) Lamp switch. H, S and T ... Head, side and tail lamps on and accessories
(b) Ignition and charging switch. available.
(c) Push-button for instrument board lamps. P.L. ... ... “Parking lights”, side and tail lamps on, acces-
(d) Socket for inspection lamp plug. sories off.
(e) A lock which can be locked and the key withdrawn with A separate ignition switch is provided, marked ON and OFF
the switches in only two positions:- Normally, this switch can be left in the “on” position, and the switching
to start and stop the engine can be carried out on the master switch.
(1) When both ignition and lamp switches are at the No independent charge position is provided owing to the presence
off position. of the output regulator. Whenever the master switch is on, connections
(2) When ignition is at the off position, but the lamp are made which cause the dynamo to charge the battery through the
switch is at the S and T position. regulator, as elsewhere described.
Do not try to lock the switch in other positions. Radiator Shutters.
The switches (a) and (b) are operated by thumb levers, and the The radiator shutters are controlled automatically by means of a
various combinations controlled by each are clearly indicated by the thermostat in the upper radiator tank.
letters as follows:- A themometer is provided on the instrument board to indicate
OFF ... ... No circuits in action. that the shutters are operating properly and that there is no shortage of
S and T ... Side and tail lamps on. coolant.
H, S and T ... Head, side and tail lamps on. The hand-operated ventilators on the sides of the bonnet should
be left open in hot weather.
12 ROLLS-ROYCE 25-30 H.P. CAR

Overheating.
If on long ascents which call for full throttle, “boiling” should
occur due to abnormal conditions of atmospheric temperature, and,
or, following winds, etc., it is preferable to change into a lower gear
and reduce the throttle opening.
Adjustment of the fan belt may be necessary, and this should
receive attention.

Fitting of Snow Chains.

In the event of snow chains being necessary, they should be
fitted to the rear wheels only.
A Parsons’ chain, known as the “Special Rolls-Royce Type”, is
available. It is recommended that these be obtained through Messrs.
Rolls-Royce Ltd., or one of their Special Retailers, in order to ensure
the supply of the correct type.
When fitting these special chains, it is essential to commence
by fastening the one hook on the inside of the wheel and always to
take up the adjustment on the outside, where two fastening clips are
provided. The tensioning springs which are supplied to go on the
outside of the wheel must always be fitted.
 PERIODIC LUBRICATION AND ATTENTION. 13

CHAPTER II

Periodic Lubrication and Attention

LUBRICANTS RECOMMENDED
Rolls-Royce Limited recommend a first quality oil of viscosity
S.A.E. 30 for the engine and gearbox all year round.
NOTE.- The recommended oil for use in the engine may require
slight modification if the engine is in very poor condition, in which case use
of an S.A.E. 40 viscosity oil may be to advantage.
Any of the following oils are suitable:-
“A” “B” “C”
Engine. Gearbox Hand-oiling
S.A.E. 30. S.A.E. 40. Points.
Price’s Energol ... 30 40 30 20
Wakefield’s Castrol ... X.L. X.X.L. X.L. Castrolite
Shell ... ... ... X. 100 X.100 X. 100 X. 100
S.A.E. 30 S.A.E. 50 S.A.E. 30 S.A.E. 20
Duckham’s Adcoidised NP NP NP NP
“Thirty” “Fifty” “Thirty” “Twenty”
Essolube ... ... 30 40 30 20
Gulf Oil (Great Britain) Speedolene Speedolene Speedolene Speedolene
Ltd. T B T 20
In the instructions which follow, reference is made to Oil “A”,
“B” or “C”.
Rear Axle.
Wakefield’s Special Castrol Hi-press S.C. (No other oil is recom-
mended, but in extreme circumstances, if this is unobtainable, use a first
quality hypoid oil. Do not mix.)
Steering Box, Chassis Oil Pump and Starter Motor Gears.
Viscosity 30 as under “A” above.
Hydraulic Shock Dampers.
As under “C” above Do not mix.
Front and Rear Hubs.
Belmoline C, Retinax R.B., or similar type of ball-bearing grease.
Propeller Shaft, Contact Breaker Cam and Wheel Hub Shells.
Retinax C.D., Mobilgrease No. 2, or a similar type of grease.
 Front Axle Control
PERIODIC LUBRICATION AND ATTENTION. 15
Front Spring Shackle (ZT.3) and Shock
(ZS.2) Damper Connec- Distributor Lubricator
Front Brake Operating tions (ZE.3)
Shaft (inner
As under “C”
Front Ball Joint of Side
bearing) (ZT.1)
Steering Tube Water Pump
Front Brake Camshaft (Supplied Direct)
(S.1) Belmoline A, Retinax P, or a similar type of grease.
Upper Pivot Bearing
Front Brake Operating
Shaft (outer (S.2) CAPACITIES
bearing) (S.0) Ball Joints of Cross Engine ... ... ... ... ... ... I¼ gallons
Steering Tube
Supply to Front Axle (Supplied Direct) Gearbox ... ... ... ... ... 5 pints
Front Spring Pin and Rear Axle ... ... ... ... ... 2 pints
Spring Leaves(ZS.1) Cooling System ... ... ... ... ... 3¾ gallons
Steering Lever Shaft Fuel Tank ... ... ... ... ... 18 gallons
Foot Operated Oil Pump and Ball Joint (ZE.1)
for Chassis System Chassis Oil Pump ... ... ... ... 2 pints
Clutch Thrust Race
Fulcrum and Countershaft of (ZT.00) CENTRALISED CHASSIS LUBRICATION SYSTEM
T-shaped Balancing Lever
(ZT.0) Pedal Shaft (ZT.0) General
Front Brake Equaliser A foot-operated pump,with which is combined an oil reservoir, is
and Shaft (ZS.2)
located on the front of the dashboard, and supplies oil under pressure for
Cylinder of Servo Clutch Withdrawal
Damper (ZE.0) Shaft (ZT.2 chassis lubrication.
Foot Brake Equaliser Hand Brake Lever A diagram of the complete system is given in Fig. 3, the piping
(ZS.0) Fulcrum (ZT.0) being coloured red. . Red discs indicate the position of drip plugs, and
Hand Brake Equaliser Foot Brake Equaliser the rating of each is given in parentheses against the description of the part
Shaft (ZE.00) Shaft (ZT.00)
lubricated.
Hand Brake Equaliser
(ZE.00 Foot-operated Oil Pump.
The chassis oil pump is shown in Fig 4. Normally no attention
to the system is necessary beyond filling of the reservoir with engine
Rear Spring Pin oil after removal of the filler cover, A. This should be done every
and Spring Leaves 2,500 miles, as directed on page 20. It should not be filled above I
(ZS.2)
inch from the top of the filler cover.
Supply to Rear Axle When the reservoir is nearly empty it will be found that the
Rear Brake
Intermediate Levers pedal returns instantly after depression, due to the presence of air in the
(ZE.0) system.
On the other hand, if the pedal takes an abnormal length of time
Rear Shock Dampers
Connections to return to its raised position, this may indicate that the felt strainer
(Supplied Direct) located at the botom of the reservoir is choked. Under these circum-
Rear Brake Lever
Shaft (ZS.1) stances a new felt strainer must be fitted.
This is arranged at the bottom of the reservoir and is removed
Rear Brake Camshafts by disconnecting the two unions, B, and unscrewing the cap, C. An
Foot Brake (TS.3) aluminium distance washer, the felt strainer pad, and a wire gauze
Hand Brake (ZT.3)
support can the be taken out.
When replacing the parts, the wire gauze support should be
Rear Spring Shackle re-fitted in the cap first, followed by a new felt pad, and, finally, the
(ZS.3)
RR 25/30 NO XVII aliminium distance washer with its recessed face towards the felt pad.
Fig. 3.- DIAGRAM OF CHASSIS LUBRICATION SYSTEM Packing washers are provided on either side of the aluminium washer
and it should be observed that these are in position.
16 ROLLS-ROYCE 25-30 H.P. CAR PERIODIC LUBRICATION AND ATTENTION. 17
Normally, the felt strainer pad should be discarded and a new one
fitted every 20,000 miles, as directed on page 24.
It should never be necessary further to dismantle the pump.

Fig. 5. - STRAINERS ON FRONT AXLE

The felt strainers should be renewed every 20,000 miles, as directed
on page 24, the procedure being as follows:-
I. Carefully clean the outsides of the fittings with a brush and
Fig. 4. - FOOT-OPERATED CHASSIS OIL PUMP paraffin to prevent the ingress of dirt during dismantling.
Drip Plugs. 2. Unscrew the outer plug, G, with a box spanner.
The drip plugs are non-adjustable and non-demountable, and 3. Unscrew the inner plug , J, with a box spanner. This plug
are lettered and numbered to indicate their shapes and relative rates of carries the felt strainer, K, which should be removed and
oil emission respectively, a higher number indicating a greater rate. discarded.
The drip plugs never require cleaning, and, being non-demountable
All parts should be carefully cleaned and freed of every trace of
no attempt must be made to take them apart. If one is suspected of being
grit before replacing. The perforated backing washer, L, must be
defective, it should be replaced with a new plug of the same rating.
replaced in the inner plug, J, before fitting the new felt strainer, K,
Front Axle System. with its gauze-covered side towards the washer.
The arrangement of the front axle system renders it necessary to Two aluminium packing washers are provided, one, JI, between
provide separate strainers. For convenience these are located on the ends the inner plug, J, and the bottom of the recess in the axle, and the
of the axle, as shown in G, Fig. 5, which also shows the component other, GI, under the shoulder of the outer plug, G. Care must be
parts inset. taken to replace these.
 PERIODIC LUBRICATION AND ATTENTION. 19

SUPPLY TO DYNAMO

OIL DISTRIBUTING MAIN

OIL LEVEL INDICATOR

DRIVE GEAR

OIL FILLER
Points of Regular Attention according to

MAIN BEARING
CONNECTION
PUSH RODS
OIL RETURN
use of Car

FRONT END ELEVATION

DAILY.
Engine Oil.
When engine is not running, inspect level indicator on left side of
crankcase and maintain quantity of oil at one-and-a-quarter gallons.
If necessary, add oil through filler by means of a strainer funnel.
SUPPY TO ROCKER SHAFT
PRESSURE GAUGE ON
HOLLOW ROCKER SHAFT

OVERFLOW FROM RELIEF VALVE

Do not run engine with indicator showing less than three-quarters
INSTRUNEMT BOARD

OIL JET TO TIMING

DRAIN
PLUG
of a gallon.
GEAR

OIL PUMP
Radiator.

RELIEF VALVE
Inspect coolant level and maintain half-way up return pipe. (See

Fig. 6. - ENGINE LUBRICATION SYSTEM

L, Fig.21.)
Chassis Lubrication.
DELIVERY PIPE
Depress oil pump pedal once while engine is being started for
SUCTION PIPE
first time in the day, and subsequently once every 100 miles. (If car is
to be driven only a few miles, half a pumpful will be sufficient at first
OIL DISTRIBUTING MAIN

starting.)

EVERY 2,500 MILES

OIL RETURN
PUSH RODS

Dynamo Bearings
DRAIN PLUG

Inject two or three drops only of oil “C” with the oil can into each
lubricator.
Battery Ignition Governor.
Inject a few drops of oil “c” with the oil can into spring-lid
OIL LEVEL (1¼ GALLONS)

lubricator.
OIL STRAINER

Cam of Battery Ignition Contact Breaker.

Smear a trace only of grease on cam surface.
Water Pump Bearing and Gland.
Remove lubricator cap, fill one-third full of recommended grease
CAMSHAFT

and screw right down, preferably when engine is warm.

OIL PRESSURE

Steering Box.
GAUGE

Remove plug and fill with oil “A” to mouth of plug orifice.
20 ROLLS-ROYCE 25-30 H.P. CAR PERIODIC LUBRICATION AND ATTENTION. 21
Chassis Lubrication.
Inspect oil level in reservoir and add more oil “A” if necessary. As each contact screw is adjusted, its locknut should be securely
Only fill to one inch from top of filler cover. tightened up.
Valve Rocker Clearances. Fan.
Check and reset if necessary. These should be .006” for both the Tension on the belt should be such that one side, at a point equi-
inlet and exhaust, when engine is cold. distant from the pulleys, may be moved transversely with the fingers
through about ¾”.
Check and adjust if necessary. (See Fig. 22.)
Brakes.
Adjust if necessary. (See page 40.)
Wheels
Test hub nuts for tightness with the spanner.
Battery.
Inspect level of acid in each cell (see page 51). This is most im-
portant. (In tropical climates it should be done more often.)

EVERY 5,000 MILES

Starter Motor
Remove plug on side of reduction gear casing and fill to plug
orifice with oil “A”.
Gearbox
Inspect oil level by means of dip stick when gearbox is warm.
Level should stand at notch in flat of stick, UI, Fig. 8. Add oil “B”
if necessary.
Fig. 7.- ADJUSTING THE VALVE ROCKER CLEARANCES.
Rear Axle
The method of adjusting the valve rocker clearances is illustrated
in Fig. 7. Inspect oil level when axle is warm by removing overflow plug
The ball ended contact screw, V, is screwed into the rocker and on rear near side of casing. Warm oil thoroughly and add through
locked bu a nut, U. On releasing the nut the screw can be turned filler plug hole at top of casing until it just commences to run out of
by means of the special spanner provided. overflow hole.
A feeler gauge is provided in the tool kit, and is shown in position See that washers are in position on plugs before replacing.
None but the recommended oil must be used (See page 13.)
at W for measuring the clearance. The exhaust rockers are marked
EX. Fan
Before commencing to adjust a valve rocker, it should be ascertained Inject a few drops of oil “C” into lubricator, A (Fig. 22).
that that particular tappet roller is well away from the cam, which Contact Breaker of Battery Ignition
is best done by turning the crankshaft by hand until the valve has Move aside spring which retains rocker arm and lubricate pivot pin with
opened and closed, and then cranking round half a revolution beyond one drop of oil “C” (See page 51.)
this point.
22 ROLLS-ROYCE 25-30 H.P. CAR PERIODIC LUBRICATION AND ATTENTION. 23
Shock Damper Control.
Bonnet Ventilators, Fasteners and Locks Inspect oil level by removing plug from filler spout. Use only
Carefully lubricate with the oil “C” to avoid squeaks and rattles. correct oil. (See page 13.)
Brake Connections etc. Dynamo.
Lubricate with oil “C” by means of the oil can, all joints and pins Remove cover, clean away brush dust and inspect brushes.
of brake ropes, rods, and connections on both axles, on servo and on Universal Joints.
brake equaliser shafts, countershafts, etc.
Turn propeller shaft so that lubricators S (Fig. 8) are at bottom and
Control Mechanism. air release plugs, T, at top. Remove plugs then inject recommended
On steering wheel (small oil hole), steering box, engine, carburetter grease with gun until it commences to flow freely from plug hole.
and ignition tower; accelerator pedal and countershaft near steering Carefully replace plugs. On no account operate gun with vent plugs
box (lubricators); also radiatot shutter control, shock damper control in position,
and pedal connections. Apply a drop of oil “C” with the oil-can to
each bearing and joint.
Engine Oil Strainer
When engine is warm, drain crankcase and remove and clean
crankcase oil strainer. (See Fig. 6.) Refill with fresh oil to correct
level.
Fuel Strainer.
Remove and clean gauze strainer on fuel inlet to carburetter float
chamber taking care, first, to see that ignition is switched off and fuel
pumps are therefore inoperative.
Air Cleaner.
Remove cleaner element and carefully wash in petrol or paraffin.
When touring on the Continent this should be done every 2,500 miles.
Fuel Tank.
Release (but do not remove) drain plug at bottom of main tank to allow
any accumulated water to escape
Spark Plugs.
Remove and clean. Set gaps to .020”.
Wheels.
Remove , grease interiors and hubs, and replace. Fig. 8.- GEARBOX AND FORWARD UNIVERSAL JOINT

EVERY 20,000 MILES

EVERY 10,000 MILES
Gearbox and Rear Axle.
Hydraulic Shock Dampers. Drain out all the oil when warm by removing drain plugs and
Inspect oil level and add more oil if necessary, using the small filler plugs provided the correct oils are available for refilling. (See
syringe. Use only correct oil. (See page 13.) page 13,) (There are two drain plugs in gearbox.)
24 ROLLS-ROYCE 25-30 H.P. CAR PERIODIC LUBRICATION AND ATTENTION. 25
Refill with fresh oil to correct level. Removal of Wheel.
Use only correct oil for cleaning out casings. Do not use petrol, Dunlop detachable wire wheels are fitted, and a special spanner is
paraffin or other oil solvents. provided in the tool-kit for removing and replacing them.
Chassis lubrication System. In Fig. 9 the spanner is shown in postion on a wheel.
Remove and discard three felt strainer pads located, respectively Before using the spanner, the central screw, P, must be unscrewed
one at base of chassis oil pump (see Fig. 4) and one at each end of as far as possible. After jacking up the car, the spanner can be placed in
front axle (see Fig. 5). Replace with new pads. position by pressing the levers, Q, to clear the shoulder on the hub nut.
Brake Servo. On releasing these levers, it should be noticed that they fit correctly into
the groove provided for the purpose.
Test adjustment and readjust if necessary.
Air Cleaner.
Renew cleaner element. (See page 30.)
Fuel Strainer.
Remove and clean gauzes of strainer on rear frame cross member
in front of tank. Drain strainer sump and wipe out with a piece of
clean, damp wash-leather. (See page 30.)
CARE OF DUNLOP WHEELS AND HUBS.

Fig. 9.- REMOVING DETACHABLE WHEEL. Fig. 10. - SECTION OF FRONT HUB.
26 ROLLS-ROYCE 25-30 H.P. CAR PERIODIC LUBRICATION AND ATTENTION. 27
Screw P should then be turned until the serrations of the locking
plate R, are seen to be clear of those on the hub nut. The latter The locking plate should now be allowed to come forward by
can then be turned in an anti-clockwise direction and the wheel turning the small lever, P, in an anti-clockwise direction, in order that
withdrawn, the hub nut remaining in the spanner. its serrations shall engage those of the hub nut.
The thread of the hub nut is right-handed for all wheels. It should be observed that when jacking up a rear wheel care is
When replacing a wheel, care must be taken that the engaging necessary that the head of the jack is arranged in the proper position. It
surfaces, serrations and threads of both hub and wheel are free from should be imediately under the axle, between the two “U” bolts which
road grit and other foreign matter. Preferably, they should be slightly secure the axle and spring together.
greased. Care of Wheels.
Every 2,000 miles, the hub nuts should be tested for tightness with
the spanner.
On no account should the car ever be run with a wheel even slightly
loose, as this will cause irreperable damage to the serrations and screw
threads.
It is necessary to try each hub nut periodically with the spanner,
and tighten if necessary. In order to tighten the hub nut, it is necessary
for the locking plate to be forced back by means of rotation of the small
lever, P, until its serrarions are disengaged from those of the hub nut.
Lubrication of Wheel Bearings.
The wheel bearings are filled with ball-bearing grease in the first
instance, and should run a long period without attention.
Sections of the front and rear hubs are given in Figs. 10 and 11
respectively.
Replacement Tyres.
Wheels are 19” well-base rims and Dunlop C type tyres, size
6.00-19, are fitted.
With regard to inner tubes, it is only necessary to state the size
and to mention “well-base”. Tubes made for flat-base rims should
not be used.
Inflation of Tyres.
The pressure for the 6.00-19 Dunlop C tyres should be as
follows:-
Front tyres, open and closed cars ... 30 lbs. per sq. inch.
Rear tyres, open and closed cars ... 35 lbs. per sq. inch.
Balancing the Road Wheels.
It is most important, in view of the high speeds attainable, that the
road wheels should be properly balanced. Therefore it is necessary to
Fig. 11 - SECTION OF THE REAR HUB. have all wheels balanced and to re-balance a wheel after changing its
tyre.
The hub nuts must be tightly screwed up by means of the special An out-of-balance effect is usually present in the complete wheel
spanner, and the use of the mallet in conjunction with it, to ensure and tyre due to:-
absolute tightness.
28 ROLLS-ROYCE 25-30 H.P. CAR PERIODIC LUBRICATION AND ATTENTION. 29
(a) The valve and its patch on the inner tube; 3. Lead balancing washers, T3, up to seven in number on any
(b) The joint of the inner tube; and one bolt.
(c) Unavoidable irregularities in the outer cover due to move- 4. Steel washer, T4.
ment of the material during vulcanising. 5. Nut, T5, for retaining lead washers.
6. Cover, T6.
7. Steel Washer, T7.
8. Cap nut, T8, for retaining cover.
To balance a wheel, all the lead washers should first be removed
from each bolt, the other parts being fitted as indicated above.
The front axle being jacked up, the wheel must be turned gently
and allowed to come to rest.
The lowest point of the tyre should then be marked.
The operation should be repeated, and if the original mark returns
to the bottom position, one or more lead washers should be added to
the bolt on the opposite side of the wheel.
If the mark made on the tyre is adjacent to the bolt, then one lead
washer should be fitted on each of the other two bolts.
On the other hand, if no bolt should lie on the vertical centre line
through the marked point on the tyre, the washers of the two bolts
furthest from the mark must be altered, for instance, if the distance of
one bolt from the centre line is approximately twice that of the other,
two lead washers should be fitted on the bolt nearer to the centre line
and one lead washer on the other bolt.
This process should be continued until the wheel will remain in
any position in which it may be brought to rest, the number of lead
washers being kept down to a minimum consistent with good balance
of the wheel.

Fig. 12 - WIRE WHEEL WITH BALANCE WEIGHTS.

A red spot on the outer cover wall indicates its lightest part, and
the cover should be fitted so that the red spot is at the valve position.
To correct such out-of-balance, three bolts are provided, spaced at
equal intevals around the wheel rim, as shown at S, T and U in Fig.
12, and each carries a number of lead washers, enclosed by a metal
cover.
One of the bolts, T, is shown with its cover and washers dismantled.
The parts are assembled on the bolt in the following order:-
I. Rubber washer, TI, which acts as a seal against the ingress
of water.
2. Special steel washer, T2, which forms a firm base for the
cover and the lead washers.
30 ROLLS-ROYCE 25-30 H.P. CAR FUEL SYSTEM 31

CHAPTER III

Fuel System
The Fuel System - Fuel Pumps - Petrol Fillers - Action of the
Carburetter - Accelerator Pump - Economiser Jet - Strangler Control for
Starting - Adjustment of Carburetter - Setting of Idling Adjustment -
Diagnosis of Faults - Float Feed Mechanism - “Hot Spot” - Air Silencer
and Cleaner.
The Fuel System.
The fuel supply from the 18 gallon tank at the rear of the chassis is by means
of a double electric pump mounted on the front of the dashboard.
A filter is arranged on the rear frame cross member immediately in
front of the fuel tank, and the supply pipe is carried along the off-side frame
member, to another filter and thence to the carburetter float chamber.
A green warning lamp on the dashboard, operated by special contacts
on the tank unit of the level gauge, is illuminated when the fuel level falls to
about two-and-a-half gallons.
Fuel Pumps.
The fuel pumps are of the electric solenoid-operated, diaphragm type. Fig. 13. - FUEL STRAINER DISMANTLED.
Both pumps deliver into a common chamber and are simul-taneously
rendered operative when the ignition is switched on. When refitting the cover, C, care must be taken that the cork
Duplicate pumps are provided primarily for reliability. washer, Cw, is sound and properly in position and the nut, E, tightly
Failure of fuel supply to the carburetter is likely to be indicated by screwed up. Any leaks on this - the suction-side of the pumps, although
audible and rapid operation of the pumps. they may not be apparent by leakage of fuel, will impair the proper
Petrol Fillers. functioning of the pumps by admitting air to the latter.
The rear filter is provided with two circular gauzes located above a large In addition, a small gauze filter, shown at B in Fig. 16, is arranged
settling sump. Fuel passes upwards through these gauzes, and dirt settles on on the carburetter. This should be removed and cleaned every 5,000
their lower faces and in the sump. miles, as directed on page 22.
The filter is shown dismantled for cleaning in Fig. 13. It should be Removal is effected by unscrewing the plug, BI, when the gauze,
cleaned every 20,000 miles, as directed on page 24. B, can be removed and cleaned in petrol.
To do this, the wing nut, E, must be released, stirrup, F, swung When refitting the parts, care must be taken that the aluminium
washer is in position on the plug.
forwards, and the cover, C, removed. The knurled nut, Fn, should
then be unscrewed and removed, carrying with it two gauzes, Fg. Action of the Carburetter.
These are held apart by a distance piece, Fd, and retained on the nut The carburetter is a down-draught model of the plain tube type
by a spring ring, Fr, and washer, Fw. The spring ring should be re- with an economiser jet. It is provided with a mechanically operateed
moved and the gauzes taken off and cleaned in petrol. Before replacing accelerator pump and an extra jet coupled with the throttle control, for
them, the filter sump should be drained by removing the plug, Sp, and acceleration and for full power running conditions, respectively, as
wiped out with a clean, damp washleather. will be described.
32 ROLLS-ROYCE 25-30 H.P. CAR FUEL SYSTEM 33
The action of the carburetter will be understood by reference
to the accompanying illustrations, in whci Fig. 14 is a diagrammatic
sectional view, Fig. 15 shows the carburetter partly dismantled, and in
Fig. 16 it is seen in position on the engine. Like references are used
for the same parts in all three illustrations.
Referring more particularly to the diagram, Fig. 14, fuel flow to
the float chamber, J, is controlled by the usual float, JI, and needle
valve, J2. The main fuel metering orifice, K, is located at the base
of the emulsion jet, KI, which projects into the throat of the small or
inner venturi tube. Air is admitted through a “bleed” orifice, K2, and
this air is mixed with the fuel forming an emulsion within the jet, KI.
The main air flow is downwards, from the silencer, and by means of
the inner venturi tube the velocity of the air is raised considerably
and the emulsion drawn from the jet, KI, is effectively pulverised and
mixed with the ingoing air. Air also passes around the inner venturi
between its outer walls and the inside of the outer venturi tube, thus
forming an annular blanket of air around the central core of mixture.
This serves to keep the mixture in the centre of the airstream and the
liquid fuel from depositing on the walls until the “hot spot” is reached.
The main metering jet, K, the air bleed, K2, the two venturis and
the size and location of the air bleed admission holes in the sides of
the jet, KI, are all so proportioned that the required quality of mixture
is maintained between small and large throttle openings.

Fig. 14 - DIAGRAMMATIC SECTIONAL VIEW OF CARBURETTER.

J- Float Chamber. N- Accelerator pump plunger.
J1- Float. N1- Pump metering and delivery jet.
J2- Needle valve. N2- Pump coupling link.
J3- Fulcrum pin of float. N3- Lever fixed on throttle spindle.
K- Main metering jet. O- Economiser metering jet.
K1-Emulsion jet. O1- Economiser valve.
K2-Main air bleed. O2- Fuel passage from economised jet.
L- Pilot or slow running jet. O3- Tappet for economiser valve.
L1, L2- Slow running discharge holes. P- Strangler valve.
L3- Slow running mixture adjustment. P1- Projection on strangler operating lever.
L4- Anti-syphonic air bleed. P2- Strangler control valve.
M- Throttle valve. P3- Cam coupling strangler control to throttle.
M1-Throttle stop screw. P4- Lever free on throttle spindle. Fig. 15. - CARBURETTER PARTLY DISMANTLED
34 ROLLS-ROYCE 25-30 H.P. CAR FUEL SYSTEM 35
In order to get from slow running and idling, under which The result is instantaneous response to throttle opening and good
conditions the air velocities through the main venturi tubes are too acceleration or “pick-up”.
low to effect reliable carburation, a pilot or slow running jet, L, is
arranged to deliver mixture to two holes, LI and L2, in the carburetter There are two alternative positions provided for connection of the
body adjacent to one edge of the throttle valve, M, when this is in link, N2, with the lever, N3. That recommended as being the more
the closed position. Bleed air is admitted to the idling system by an satisfactory is the inner hole, as the link is shown connected in Fig. 14.
adjustable needle valve, L3, which also serves as a means of adjusting Economiser Jet.
the quality of the slow-running mixture. In addition another and A further characteristic feature of the carburetter is the provision of
non-adjustable air bleed, L4, is provide in order to prevent flooding what is known as an “economiser jet”. This consists of an additional jet
through the slow running holes by syphonic action in the event of the which is only brought into action when the throttle is well opened.
adjustable air bleed, L3, being inadvertently screwed right in to shut
off the bleed air at the point. It is well known that there is a considerable difference in the fuel
mixture strength necessary, on the one hand, for the most economical
The size of the pilot jet, L, in conjunction with the sizes and running, and on the other, for maximum power.
positions of the two holes, LI and L2, are selected to ensure smooth,
slow running and an uninterrupted change-over from the pilot to the The presence of the economiser jet enables both conditions to be
main jet as the throttle is opened. met, the main metering jet, K, being selected for economical cruising
conditions, gives a mixture on the lean side consistent with smooth
Accelerator Pump. running, full power requirements being met by additional fuel from the
Under conditions of running when the throttle is moderately or economiser jet.
fully open, the insides on the induction passages are wet with fuel The economiser metering jet is shown at O, in Fig. 14. It is
deposited from the main mixture stream. The condition is unavoidable controlled by a valve, OI, normally kept closed by a spring. When the
and is not detrimental with a correctly designed manifold and “hot throttle is nearly fully opened, the stem of this valve is depressed by
spot”. Under closed-throttle conditions, however, the passages are the same member as that which operates the accelerator pump. The
dry, or more nearly so, owing to the reduced pressure in the induction additional fuel flows to the main jet by way of passage, O2.
system in conjunction with the smaller quantity of mixture flowing.
The precise throttle position at which this jet is brought into
Sudden opening of the throttle, therefore, may cause a temporary action is carefully predetermined and should never need adjustment.
breakdown in the carburation due to the disposition of liquid fuel or A useful guide in the event of re-setting becoming necessary, due, for
“wetting” of the interior surfaces robbing the mixture stream, and instance, to accidental derangement, is as follows:-
until this “wetting” has taken place the mixture equilibrium in the
manifold will not be stabilized. The condition is aggravated by the A ⅜” diameter rod or mandrel should be inserted into the lower
inertia of the fuel in the various passages. or outlet end of the carburetter, between the throttle valve and the
To meet these conditions, a pump, known as the accelerator pump, barrel. The throttle should then be lightly closed against the rod and
is provided, which is coupled to the throttle operating mechanism in the adjustment, O3, provided on the economiser jet operating arm, so
such a manner that opening movement injects the necessary amount set that the valve spindle and operating tappet are just in contact.
of additional fuel into the mixture chamber. Strangler Control for Starting.
The pump plunger, N, is arranged in a compartment of the float To ensure asy staring from cold, a strangler or choke valve is
chamber. It draws fuel from the latter through a disc valve and arranged on the upper or inlet end of the carburetter. It is of a special
delivers it past a ball valve and a metering jet, NI. The plunger is kind designed to eliminate the risk of over-strangling or “choking”.
coupled by a rod and link, N2, to a lever, N3, fast on the throttle Control is from a thunb lever on the instrument board, the dial plate
spindle. Closing movement of the throttle, M, raises the plunger of which is marked Start and Run.
positively and draws fuel into the plunger cylinder. Opening movement
of the throttle, however, does not positively force the plunger down- The strangler valve is shown dotted at, P. Its spindle is mounted
wards to expel the fuel, but does so through the medium of a spring. off-centre and a projection, PI, on the operating lever is kept in
The tension of this is such that a very sudden opening movement contact with an arm of the control lever, P2, by a light spring. As a
compresses it against the plunger which subsequently falls more or result, suction of the engine, or more correctly, atmospheric pressure,
less gradually, thus ensuring that the mixture is maintained in proper tends to open the valve, acting against the larger offset area of the
proportions until the main emulsion jet comes into action. valve and against the spring and separating the projection, PI, from
36 ROLLS-ROYCE 25-30 H.P. CAR FUEL SYSTEM 37
the control lever arm. As an additional safeguard against over- To ensure the correct amount of opening and thereby to relieve
strangling a lightly spring-loaded disc valve is fitted in the strangler the driver from the need for precise setting of the hand throttle control,
valve itself which also tends to open under engine suction. with the risks of false starts, the strangler control is interconnected
An engine usually starts more easily from cold if the throttle be set with the throttle lever to cause the throttle to open the required
a certain small amount open, this degree of opening being invariably amount when the instrument board control lever is set to Start.
more than that required for normal idling when the engine is warm. The strangler control lever, P2, carries a roller which makes
contact with a cam, P3, forming part of another lever. The latter
is coupled by a rod with a lever, P4, freely mounted on the throttle
spindle. A projection on this lever makes contact with a projection
on the accelerator pump operating lever, N3, and causes the throttle
to be opened by a predetermined small amount when the strangler
control is set to Start.
There is consequently no need for the driver to set the hand throttle
lever open when using the strangler. On the contrary, it is necessary
hat the hand control should be at the bottom of its quadrant in order
to avoid interference with the degree of opening as determined by the
operating cam.
An adjustment of this degree of opening movement is provided at
the point where the rod is coupled to lever, P4. Readjustment should
not normally be necessary, but if the original setting is disturbed it
may be restored as follows :-
Release throttle stop screw, MI, until the throttle is entirely
closed and then bring the screw back until it just makes contact with
the throttle lever without moving the latter. Next, set the adjustment
between the rod and the lever, P4, so that operation of the strangler
control causes the throttle to be opened by an amount equivalent to a
gap of .060” between the stop screw and the throttle lever.
It will subsequently be necessary to re-set the stop screw as later
described.
Adjustment of Carburetter.
There should be no necessity for any variation of the adjustments
of the carburetter as fixed by the makers. Great care is taken during
testing of the car to secure the best settings, and these should not,
under normal circumstances, be altered.
All jets and air bleeds are marked with a number indicating the
size of the orifice. These orifices should not be reamed or tampered with
in any way. If replacements are required, application should be made to
Rolls-Royce Ltd. for parts with the same numberings.
There are certain external adjustments, however, which are dealt
with in the following paragraph.
Setting of Idling Adjustments.
The idling adjustments should only be re-set when the engine
is well warmed up. There are two adjustments, namely, the throttle
stop screw, MI, and the idling mixture adjustment screw, L3. The
Fig. 16. - CARBURETTER IN POSITION ON ENGINE latter is locked by a lock nut.
38 ROLLS-ROYCE 25-30 H.P. CAR FUEL SYSTEM 39
With the hand throttle in the closed position, the throttle The standard setting of the fuel level is ⅝” below the top face
stop screw, MI, should be adjusted to give the desired engine speed. of the float chamber. Normally, it should not be necessary to alter
The mixture regulating screw, L3, should then be turned in and out this. If readjustment should at any time become necessary, however,
until a position is found where the engine rhythm is most regular. alteration can be effected by carefully bending the float arm where
Screwing in gives a richer mixture, and screwing out a weaker one. If it meets the float. Bending the float up will raise the level, and vice
a satisfactory position cannot be found, the idle discharge holes, LI versa.
and L2, should be inspected by removing the small plugs seen in “Hot Spot”.
Fig. 15. The pilot jet, L, may be removed for inspection by taking
off the float chamber cover. A “hot spot” is provided in the induction manifold immediately
After seting the mixture adjustment screw, it may be found opposite the carburetter by virtue of the fact that the induction
necessary to re-set the throttle stop screw. manifold is bolted direct to the exhaust manifold at this point. The
joint should not be disturbed.
Diagnosis of Faults. A fuel drain, T, Fig. 16, is arranged which incorporates a non-
In the event of faulty running or misfiring developing, a systematic return valve normally kept closed by engine suction. The pipe is
investigation of possible causes should be made, e.g. the correct united with that from the float chamber cover and also with another
functioning of the ignition system, cleanliness and setting of the ignition one from the tray, U, Figs, 15 and 16, below the carburetter to trap
plugs, sufficient fuel in the tank, cleanliness of the fuel strainers and any leakage fuel.
correct operation of the fuel pumps; all these should be checked.
Air Silencer and Cleaner.
If such investigations leave the carburetter itself under suspicion, A cleaner is arranged within the front end of the air silencer to
the following points should be investigated:- prevent the passage of dust and grit to the engine.
For loss of maximum speed. - Check that the throttle valve can The cleaner compises a composite gauze and cotton fabric
be fully opened, and see that the economiser jet, O, Fig. 14, and element through which the air passes on its way to the carburetter. It is
valves are free from obstruction. To exract these parts, remove removed by unscrewing the three small set screws on the front end of
float chamber cover and float, withdraw split pin from link, N2, the silencer and taking off the end cover of the latter.
and take out link and withdraw pump plunger, N. The econo- Every 5,000 miles, as directed on page 22, the cleaner element
miser valve may then be unscrewed and withdrawn. should be removed and carefully washed in petrol or paraffin.
Flat spot at small throttle opening. - Adjust idling to give more When touring on the Continent this should be done every 2,500
even engine rhythm (see page 37). If flat spot is still evident, miles.
examine idle holes, LI and L2, and pilot jet, L, for stoppage. Every 20,000 miles, as directed on page 24, the element should be
Flat spot at half throttle opening. - withdraw main jet, K, and renewed.
examine fro stoppage. Check accelerator pump for stoppage. A short pipe connects the carburetter intake with the silencer
and it should be noticed that this pipe can be removed by merely
High fuel consumption. - Check fuel levels in float chamber. releasing the bolt, V, Fig. 16. There is no need to disturb the large
(See below.) If correct, and all jets are as set by makers, the serrated nut on the other end of the pipe.
most probable cause is a sticking or leaking economiser valve.
Remove and examine for foreign matter, which may be removed Care must be taken not to overtighten the bolt, V as this may
by blowing through valve orifice. distort the carburetter body and cause the strangler valve spindle to
bind in its bearings.
Float Feed Mechanism.
The float chamber is held in position by three screws and is
provided with a cork joint washer. A special form of vent, Q, Fig.16,
is fitted, and also a drain pipe to carry off fuel if flooding occurs.
The float can be removed by unscrewing the fulcrum pin, J3,
Figs. 15 and 16.
A flexible pipe, R, conveys fuel to the float chamber. On no
account must the fittings on the pipe itself be disturbed.
40 ROLLS-ROYCE 25-30 H.P. CAR ADJUSTMENT OF BRAKES 41

in the off position. Screwing on the nut through a further 90º, that
is a total of half a turn, alows the shoes to return to an off position
which is half a turn of the adjustment nearer to the drum. The
CHAPTER IV adjustment is self-locking.

Adjustment of Brakes
General - Adjustment of Brakes - Adjustment of Hand Brakes -
Adjustment of Servo

General.
The only points in the sytem where any adjustment is provided
or is necessary are the following: -
I. Foot brakes, front and A wing nut adjustment (Figs. 17 and
rear. 18), which is for hand operation only.

The threaded rods coupled to the cam

2. Hand brake ... ... operating levers below the rear axle
(Fig. 18).
3. Servo ... ... ... The serrated adjusting nut on the end
of the servo shaft (Z, Fig. 19).
These adjustments are dealt with in detail in the succeeding
paragraphs.
It is very important to observe that under no circumstances
should adjustment be attempted at any other points, for instance, by
altering the lengths of other brake rods or any of the ropes. These
are carefully determined during the erection of the chassis, with a
view to utilising to the best advantage the lengths of various levers,
taking into consideration the total movement of such levers, from the
time when the brakes are new until the facings are completely worn
out.
Any alterations to the lengths of these rods or ropes will virtually
shorten the lengths of some of the levers, and will interfere with the Fig. 17. - FRONT WHEEL BRAKE ADJUSTMENT.
correct functioning of the system. When making or testing the adjustment, it is preferable that the
Adjustment of Foot Brakes. wheel should be jacked up and rotated by hand. One is then able both
The wing nut adjustment for the front brakes is shown at Wf, to hear and to feel when the shoes make contact with the drum.
Fig. 17, and that for the rear foot-operated brakes at Wr, Fig. 18. The nut should be screwed up until the cam action described
prevents fyrther rotation with the fingers, owing to the shoes being
Only the fingers must be used in turning these nuts, They are formed applied to the drums. The setting will then be correct, and the
with cam-shaped bosses bearing on cylindrical trunnions in such a way adjustment locked if the nut be turned back one-quarter of a turn.
that the roration of the nut through 90º from the position shown causes
the brake shoes to be moved towards the drum as the cams ride over It must again be emphasised that on no account must force be
the trunnion. This movement is carefully predetermined, and is equal used in turning the nuts, as this will defeat the object of the described
to the normal clearance between shoes and drum when the shoes are arrangement and result in badly adjusted, probably dragging brakes.
42 ROLLS-ROYCE 25-30 H.P. CAR ADJUSTMENT OF BRAKES 43
Care should be taken to replace the pins, K, securing them with
split cotters and collars, then to re-tighten the nuts, M, and finally the
locknuts, HI.
Adjustment of the Servo.
The servo is of the dry, disc-clutch type, and should run 20,000
miles without the need of any adjustment.
If adjustment is necessary, it is effected by screwing up the nut,
Z, below.

Fig. 18. - REAR BRAKE ADJUSTMENTS.

It should be noted that the movement of the brake pedal when

the car is standing does not apply the front brakes, which are operated
solely by the action of the servo. Under such circumstances, pressure
on the pedal will only apply the rear brakes.
Adjustment of Hand Brakes.
All adjustment of the hand brake is effected at the outside rods
beneath the rear axle, one of which is shown at H above.
Fig. 19. - THE SERVO MOTOR AND ITS CONNECTIONS.
With the hand brake lever right off, the adjustment should be
tested by pulling the brake rope, J, with the hand and measuring
the travel of the rope necessary to just apply the brake. This travel This nut is locked by 25 rounded serrations formed on its face,
should not be less than 1”. which engage similar serrations on a washer, which is secured against
Adjusting is effected by removing the pin, K, from the jaw, L, rotation relative to the shaft. The depth of these serrations is carefully
this pin being secured by a collar and split cotter, releasing the locknut, proportioned to give the correct clearance of the servo, the nut being
HI, slackening the small nut, M, and screwing the jaw further on turned so that the teeth lightly ride over each other and engage again.
to the rod, H, to an extent depending on the amount of adjustment On no account should force be used in this operation, as such
required. treatment would nullify the object of the teeth, namely, to determine the
Usually this should be the same on both sides. correct clearance.
44 ROLLS-ROYCE 25-30 H.P. CAR THE CLUTCH 45

After effecting adjustment in this way, care should be taken to see

that the serrations are in proper engagement.
The adjusting nut should not be screwed up more than one ser-
ration - that is, 1/25 of a turn - without testing the servo adjustment.
To do this the pedal should be depressed lightly by hand sufficiently
to engage the servo and compress the buffer springs, ZI, but just short
of moving the lever A2 rotationally. CHAPTER V
The pedal travel should then be not less than ½” measured at the
top of the pedal towards the dash.
It must be realised that this movremnet is entirely due to operation
of the servo, and does not alter the rear brake clearances. Hence,
The Clutch
lever A2 is not moved rotationally, as mentioned.
After adjustment, the servo clearance should always be checked Adjustment of Clutch
again by measuring the pedal movement, as explained.
Emphasis is laid on this point, as obviously a dragging servo, due
to abuse of the adjustment provided, would result in dragging of the Adjustment of Clutch.
brakes on all wheels. The only point where any adjustment is provided is at link, D,
coupling the pedal lever to the clutch operating lever.
There must always be a certain amount of “free” or idle movement
of the pedal, as is easily tested by pressing the pedal lightly. It should
be possible to move it 1”, as illustrated, measuring horizontally
towards the dashboard, before the withdrawal sleeve is felt to be in
contact with the toggle levers.
The link, D, , is coupled to
the jaw, E, by means of a screwed
sleeve, F, having left- and right-
hand threads and provided with a
hexagon, F2.
To effect an adjustment, the
foot and floor boards must be re-
moved to gain access to the link, G
the locknuts, D1 and F1, released.
The sleeve, F, can then be rotated
with a spanner to obtain the correct
free movemnent, the locknuts F1 E
being subsequently retightened. F2

When testing and setting this D

adjustment, the aluminium pedal D1
plate must be in position, because F
it is this part which acts as the
stop limiting upward movement of
the pedal under the action of its
external spring, G. Fig. 20. - CLUTCH ADJUSTMENT
46 ROLLS-ROYCE 25-30 H.P. CAR COOLANT SYSTEM 47
Radiator Shutters.
CHAPTER VI The thermostat which operates the radiator shutters is shown at T, in
Fig. 21, and is arranged to maintain an average coolant temperature
of approximately 78ºC.
Coolant System Reference to the instrument board thermometer will indicate that
the thermostat is operating correctly and that there is no shortage of
coolant.
Collant Pump - Radiator Shutters - Coolant Level - Frost Precautions In the event of faulty operation of the thermostat, the latter
- Fan. may be quickly disconnected from the shutters. This is effected by
Coolant Pump. raising the spring-loaded pin, R, and disengaging the end of the lever,
The centrifugal coolant circulating pump is fitted with a special RI from the thermostat rod. A knob, U, is provided to facilitate re-
double packing gland. engagement.
A screw-down greaser is provided for lubricating the gland and The shutters should then be pushed open by means of the lever,
bearings. RI. They must not be moved by direct hand operation of the shutters
It should be filled one-third full of grease every 2,500 miles, themselves.
as directed on page19, and screwed right down, preferably when the Coolant Level.
engine is warm. The coolant level should be inspected daily and maintaned about
half way across the upper radiator pipe, as shown bu the white line, L,
Fig. 21.
If an anti-freeze mixture is being used, the level should be main-
tained so as to just cover the upper tubes of the radiator core.
Frost Precautions.
Where plain water is being used as the coolant medium., and there
is any liklihood of the car being exposed to low, frosty temperatures,
with the engine not running, it is of vital importance that the cooling
system should be drained by opening the drain tap on the pump inlet
pipe and releasing the radiator cap. Also, after a frost and before
attempting tp start, or even move, the engine again, hot water should
first be poured over the water pump, as otherwise damage may be caused
to the pump rotor by the presence of particles of ice within the casing.
Warm water can be used with advantage for refilling the radiator.
A suitable anti-freeze mixture is made by mixing soft water with
either inhibited ethylene glycol or “Bluecol” in proportions dependent
on the degree of frost likely to be encountered.
The following table gives an approximate indication of the amount
of frost protection ensured by different strengths of mixture.
Freezing point ... ... ... 22º F. 12º F. 2º F. -3º F.
Degrees of frost ... ... 10º F. 20º F. 30º F. 35º F.

I Inhibited Ethylene Glycol ... 4½ pts. 6¾ pts. 10 pts 11 pts.

2”Bluecol” ... ... ... ... 4½ pts. 6¾ pts. 10pts 11pts.
Fig. 21. - THERMOSTAT CONTROL OF RADIATOR SHUTTERS.
48 ROLLS-ROYCE 25-30 H.P. CAR COOLANT SYSTEM 49
When changing from water to anti-freeze, the radiator system The rubber connections must be carefully examined and replaced
must be drained. New anti-freeze of the required amount should be if unsound, as any leakage will necessitate replenishment with anti-
mixed with an equal quantity of soft water before being poured into the freeze mixture.
radiator, the radiator being finally topped up with soft water. When using an anti-freeze mixture as described, a similar mixture
The engine should then be run until normal operating temperature should beused for topping up purposes.
is reached, to ensure uniform distribution of the anti-freeze throughout
the system. Fan.
The fan and its bracket are shown in Fig. 22. A spring lid lubri-
cator, A, is provided, and a few drops of oil “C” should be injected
every 5,000 miles, as directed on page 21.. At the same time the joints
of the belt tensioning device should be lubricated with the oil can.
The tension of the belt should be such that one side, at a point
equidistant from the pulleys, may be moved transversely with the
fingers about ¾”.
The adjustment should be checked every 2,500 miles, as directed
on page 21.
Adjustment is effected by slackening the hexagon locknut, B, with
a spanner and screwing down the knurled nut, C, with the fingers until
the correct tension is obtained, afterwards securely relocking nut B.

Fig. 22. - FAN BELT ADJUSTMENT.

50 ROLLS-ROYCE 25-30 H.P. CAR ELECTRICAL SYSTEM. 51
Exide. P. & R.
First charge current ... ... 3 6
Normal charge current ... ... 5 6
CHAPTER VII Capacity when fully charged: -
Starting for 5 minutes ... ... 117 amps. 210 amps.
Lighting at 3 amperes ... ... 24 hrs. approx. 24 hrs. approx.
Electrical System Voltage across terminals ... ... 12 12
General - Battery - Battery Ignition - Sparking Plugs - Electrical Never allow the liquid in the cells to fall below the tops of the
Fault Location. separators.
Inspect the battery at regular intevals, and top up with distilled
General. water, so as to maintain the level of the liquid at ½” above the tops of
The equipment comprises a dynamo, distriution box with the plates.
fuses and automatic cut-out, automatic output regulator, switchbox, Do not inspect the battery with the aid of a naked light, and on no
ammeter, a 12-volt approximately 60-ampere-hour battery, a starter account disconnect any of the battery terminals or connections when
motor with relay-operated switch, electric horn and fuel gauge, dual any charge or discharge current is passing, for such a course incurs
electric fuel pumps and battery ignition consisting of non-trembler risk of explosion and involves personal risk.
coil with ballast resistance, and combined low-tension contact breaker
and high-tension distributor and the necessary wiring encased in Battery Ignition.
metal tubing. The battery ignition is in a very accessible position, as shown
Incorporated with the battery ignition is a governor, which effects in Fig. 24, and consists of an ignition coil, W, and combined low-
automatic control of the battery ignition timing, the effect of the hand tension contact breaker, X, and high-tension distributor, XI.
control being superimposed. A ballast resistance, RI, is connected in series with the low-tension
winding of the coil. Its function is to limit the current taken by the
The wiring diagram, Fig. 23, shows the units with their electrical coil at slow speed, or if the ignition switch be accidentally left on
connections, the various wires being indicated in colours to correspond while the engine is stopped. It also secures practical equality of
with those of their actual coverings. intensity of secondary spark at all speeds.
Battery. A condensor connected across the contact points is located in a
The battery recommended for use on this car is either: - pocket, X2, of this apparatus, the condensor case and the main body
Exide ... ... ... ... 6-XCMRII-IRL or of the contact breaker unit being together in direct electrical con-
Peto & Radford ... ... 6-HZDII-S nection with the chassis frame.
The insulated terminal of the condensor is connected to the
insulated contact, and they are brought out together to the insulated
Specific Gravity of acid (at 60º F.) terminal to which the external low-tension connection is made.
In setting the points the gap opening should be .015” to .018”.
In climates with Ordinarily below Frequently above Every 5,000 miles, as directed on page 21, the pivot pin of the
air temperatures 90º F. (32º C.). 90º F. (32º C.). low-tension rocker arm should be lubricated by moving aside the
retaining spring and putting one drop of oil on the exposed end of the
Filling in acid for Exide 1.340 1.260 pivot.
first charge P & R 1.350 1.260 A few drops of oil “C” should be injected into lubricator, Z,
every 2,500 miles, as directed on page 19, in order to lubricate the
centrifugal ignition timing mechanism. In addition, the oil so injected
Fully charged Exide 1.280 1.201 serves to maintain an oil seal arranged at the base of the ignition tower
P & R 1.280 1.210 to protect the contacts from oily vapour from the crankcase, which is
liable to cause pitting.
52 ROLLS-ROYCE 25-30 H.P. CAR ELECTRICAL SYSTEM. 53
The high-tension distributor requires no attention beyond an If the timing of the battery ignition should have been deranged,
occasional wiping of the interior with a clean, dry rag. due, for instance, to removal of the cam operating the low-tension
It is important that theoutside of the coil casing should be kept rocker, it can be re-set by reference to the flywheel markings which
clean. Also, the cover should occasionally be removed and the top of can be seen on removal of the clutch pit cover.
the coil cleaned with a dry rag. Misfiring is some times caused by an To carry out this operation, the crankshaft should be turned until
accumulation of dirt around the terminals and on the coil casing. the mark B.A.I. (battery, advanced ignition) on the flywheel registers
with the mark on the casing when No. I piston is approaching its
firing stroke.
Owing to the fact that a friction-damped spring drive is used for
driving the valve gear and all auxilliaries, and that the starting handle
operates to turn the crankshaft through the medium of this spring drive,
it is important that the crankshaft be rotated for timimg purposes from
the flywheel end. Also, the starting handle should not have been used
at all since the engine was last running.
Fully advance the ignition lever, and then set the contact breaker
cam to be just on the point of causing contact break (when turning
forward) corresponding to cylinder No. I.
A convenient method of determining precisely when the break
takes place is by reference to the ammeter. With the ignition switched
on, and someone watching the ammeter, the cam should be slowly rotated
on the tape of its shaft in the normal direction of rotation until the
required peak breaks contact as indicated by the reading of the ammeter.
The screw securing the cam should be tightened.
A spare ignition coil is provided as shown at Wr, Fig. 24. It is put
into commission by interchanging the high-tension terminals, H and
Hr, and changing over the two low-tension leads, one of which is seen
at G, from one coil to the other.
A small casing on the dashboard, marked “Ignition Spares”,
contains a spare low-tension rocker arm complete with springs and
contact point, and also a spare contact screw.
Sparking Plugs.
Either K.L.G. Type F.L.B. 30X or Champion Type LB.8, 14
m/m sparking plugs are recommended for this car. Plugs should be
removed and serviced on special plug cleaning and testing machine,
which should be available in all service stations, every 5,000 miles.
Reset gaps to .020”.
Electrical Fault Location.
An electric torch hand-lamp should be carried when much night
running is being done, in addition to an inspection lamp with a plug
which may be connected to the switchbox.
In case of faulty operation, proceed to investigate as follows: -
I. Failure of any part of the system separately may be due to a
Fig. 24. - IGNITION COILS, DISTRIBUTOR AND BALLAST RESISTANCE. blown fuse in the distribution box.
54 ROLLS-ROYCE 25-30 H.P. CAR
2. Failure of incorrect operaton of the system may be due to the
fusing of the emergenct battery fuse due to an earth
Repeated failure of a properly fitted fuse indicates a fault
on the system.
If the dynamo does not charge: -
1. Ascertain whether dynamo or regulator is at fault by removing
regulator cover and connecting terminal I to E, and terminal
A to +. This will short-circuit the regulator. Then, start
engine gently and increase speed slowly. If dynamo is in
order, the output will be delivered and the defect will lie in the
regulator.
2. Dynamo brushes may be sticking, due probably to oiliness.
Clean brushes and holders with a rag moistened with petrol.
3. Cut-out contacts may be burnt or sticking.
4. Inspect armature fuse, No. 2, in distibution box.
If dynamo oputput is low, this may bedue to battery being fully
charged, but if low with lights on, i.e. ammeter indicates an abnormal
discharge, the regulator may be sticking in such a manner as per-
manently to insert the field resistance.
If dynamo gives an excessive charge and blows fuse (No. 2), when
speeded up, this may be due to regulator sticking or to a break in the
regulator shunt coil circuit. Check regulator wiring connections.
In the case of defective operation which is traceable to the regulator, the
unit must be removed and returned for rectification to Rolls-Royce Ltd.
If, with the fuses intact, and the lights in order, the ignition: -
(a) Misses.
1. First confirm right condition of sparking plugs.
2. Assure correct condition of contact breaker points, and adjust
gap .015” to .018”, if necessary.
3. If missing still continues, test ignition circuit as below
4. Dirty ignition coil casing.
(b) Fails.
1. With battery ignition switched on, see by ammeter, while engine
is cranked, that the coil is taking current intermittently. If no
current, test availability of battery voltage on ballast resistance
terminals then at coil terminals.
If, with battery in order, starter motor is sluggish or does not turn,
examine commutator and brushes. Clean oily brushes and holders
with a rag moistened with petrol. If motor turns without turning
engine, examine Bijur drive.
If battery will not retain charge: - Fig. 25. - GUIDE TO LOCATION OF MAIN SERVICE STATION.
1. Ascertain that no circuit is left switched on.
2. See that no cell of the battery leaks acid.
Fig. 26. - GUIDE TO LOCATION OF CREWE SERVICE STATION.