PLUGS N8

TYPE T.600

PETROL ENGINE

Mk. I.

Working Instructions

and List of Parts

THE

Norman Engineering Co. Ltd.

MILLERS ROAD • WARWICK

TELEPHONE WARWICK H 8»9

FEBRUARY, 1947

INDEX Page No

Crankcase ... ... ... … 14

Intermediate Timing Wheels (Upper and Lower) 14

Magneto Drive 14

Cylinder (Left Hand) 15

Cylinder (Right Hand) 15

Camshaft 16

Connecting Rod 16

Crankshaft ... .... 16

Flywheel; Flexible Coupling and Spider 16

Governor 16

Piston 16

Air Cleaner and Elbow 17

Carburettor 17

Governor Casing 17

Magneto and Sparking Plugs 18

Starting Handle 18

Starter Shaft 18

Miscellaneous 18

Silencer and Exhaust Pipe … 18

Standard Parts 19

ALWAYS QUOTE ENGINE No. WHEN ENQUIRING

FOR

SPARE PARTS.

6 H.P., PETROL ENGINE,

TYPE T.600, MK. I The Engine is complete within itself as a power unit. It can be bolted to any

suitable bedplate to form the driving unit for an auxiliary.

Every precaution has been taken in designing this engine to ensure that the

working parts shall be protected from the ingress of dirt ; outstanding fea-

tures being the provision of covers completely enclosing the Exhaust and

Inlet Valve Mechanism, and an Air Cleaner attached to the Carburettor In-

take.

The Crank Chamber is separated from the Oil Sump by a wall of metal which

allows the engine to be carried in any desired position, even upside down,

without flooding the Cylinders, Pistons, and Timing Case with lubricating

oil.

The Crankshaft, Camshaft, Intermediate Timing Wheels, Magneto Timing

Wheel, and Governor, run on Ball Bearings. A duplex gear type Oil Pump

feeds lubricating oil to the Crankshaft under the pressure of 20 lbs. (30 lbs.

for hot climates) per square inch; the oil passing through a Filter before

reaching the distribution point. Excess oil drains into the Timing Case, and is

withdrawn into the Sump by means of the scavenging gears in the Pump.

The Engine is fitted with a detachable Starting Handle (clockwise rotation)

and an Earthing Switch integral with the Magneto for stopping purposes.

This engine has several desirable features such as: Detachable Cylinder

Heads for rapid decarbonising. Instantaneously adjusted Slow Running de-

vice. Speed Adjustment above or bekpv set speed.

The two latter adjustments, together with replenishing the oil and adjusting

oil pressure, can be made while the engine is running. The Cylinders are

made of close grained cast iron and are provided with side by side valves

and detachable Cylinder Heads.

The Pistons are made from " V " alloy castings Spec. BESA.L.24.

One scraper and two compression Rings are fitted, and the oil return holes

are in the scraper ring grooves only.

The Gudgeon Pins are retained in position in the Piston by Circlips.

The Connecting Rods, of " H " section, have bronze Small End Bushes and

split Big End Bearings of the detachable steel backed white metal type.

The Crankshaft, made from a solid drop forging is of the usual horizontal

twin opposed type, is partially balanced on its outer webs; and mounted on

ball Bearings.

The Camshaft, which is mounted on Ball Bearings above the Crankshaft, is

driven by means of a steel pinion on the Crankshaft through a bronze

idler gear to a steel wheel mounted on the Camshaft. The drivefor the combined pres-

sure and scavenge Oil Pump is through an intermediate gear from the Crank-

shaft.

All idler wheels are mounted on ball Bearings. All Gears in the Timing Case

are of ample dimensions across the face. The two inlet and exhaust Cams op-

erate directly on to the Tappets, whose ends arc hemi-sphcrical in shape. The

usual method of tappet adjustment is adopted. Single Valve Springs are fitted

and these together with the Tappets arc enclosed in easily detachable alumin-

ium casings. Cast iron Valve and Tappet Guides are used.

The Sparking Plugs are screwed into the Cylinder Heads on the flywheel side

of the engine to ensure that they will receive the benefit of the Fan Cooling.

The Flywheel is of aluminium alloy and its spokes form efficient blades of a

cooling fan to create a draught over the Cylinder Heads and under the Crank-

case, which is finned for oil cooling purposes.

Lubrication is provided by a combined pressure and scavenge gear Pump of

equal size ; the former draws oil from the Sump and delivers it via a fine Fil-

ter under the influence of an adjustable spring-loaded Relief Valve through

passages in the Crankcase to a distribution bearing on the end of the Crank-

shaft, which is drilled for the passage of oil from here to the Big End Bear-

ings. The normal oil pressure shown on the gauge is 20 lbs. per square inch

(30 lbs. for hot climate). If an oil indicator is fitted ; it is normally set for 30

lbs. pressure. The oil flows out to the bottom of the Crankcase proper,

through the timing wheels, into the outer reservoir, whence it is conducted by

the scavenge Pump into the Sump proper. A screwed Filling Plug is incorpo-

rated in the Sump.

A spring loaded copper disc outlet Non-return Valve releases pressure from

Crankcase via Breather Pipe.

The Ball Valve in Crank chamber is to ensure that no compression takes

place in the Oil Sump, so that it is possible to fill the Sump with lubricating

oil without stopping the Engine.

A Centrifugal Governor is driven from the front end of the Crankshaft and

the control arm connected to the Throttle is mounted eccentricallv in an ad-

justable fulcrum bush, so that the controlled speed can be adjusted for slow

running by rotating the Knurled Knob.

The Magneto is fitted with fixed ignition, and a very simple Switch for stop-

ping the Engine is incorporated.

Starting is effected by rotating the detachable Crank Handle which engages

with the end of the Camshaft, and therefore is geared up to 2/1 to the Crank-

shaft

.INSTRUCTIONS FOR RUNNING THE ENGINE

The references in these instructions appear in the Photographs of the En-

gine—Plates 1, 2, 3, 4.

1—. LUBRICATION.—Unscrew Oil Filler Cap indicated by " A " on the

photograph of Engine and fill sump with Vacuum Mobiloil B.B., Shell Tri-

ple, or Essolube 50, Oil. The recommended oil for the engine is Mobiloil

B.B. Capacity of Sump : 3 pints. For second choice, use Shell Triple.

2.— TO' START ENGINE.—Turn on Petrol and flood Carburettor ; but not

excessively. While facing the Starting Handle, close Air Strangler Lever " B

" on the Air Filter Elbow by moving upwards ; i.e. to the right. It is not

necessary to observe the above instructions when starting up a warm engine.

(See Note 12).

3—. The Ignition is normally switched on : to stop engine, press button on

Magneto.

4.— Fit Starting Handle " D," to Shaft, and engage Dog with Pin by pushing

Handle in and compressing Spring. Rotate Handle smartly in a clockwise di-

rection, commencing with the handle in the orthodox staring, position. Note.

Should the starting be facilitated by use of the control Knob ." E " the nor-

mal r.p.m. can be obtained by rotating this Knob to the LEFT when facing

Starting Handle. See instruction 5).

5.— SLOW RUNNING.—This Engine is fitted with a slow running device.

To obtain slow running, rotate Control Knob " E " to the RIGHT while fac-

ing Starting Handle. Full slow running is obtained after rotating Knob

through 180 degrees and the location for maximum position is by ball and

spring which can be felt to click into, position.

6—. To readjust the full load speed, rotate knob to the LEFT, until ball is felt

to be in position again. The action of adjusting for slow running does not af-

fect the initial full load speed.

7.— To adjust the engine speed above or below that at which it is set, rotate

the small Knurled Nut " F " in an anti-clockwise direction to increase the

speed, and in a clockwise direction to decrease the speed.

8—. OIL PRESSURE.—The Pressure Release Valve is situated on the left-

hand lower side of the Crankcase, facing the Starting Handle. To adjust the

oil pressure, first remove the domed hexagon cap, revealing the adjusting

screw and locknut. Hold screw with screwdriver, and slack off locknut (R.H.

thread), and rotate screw in a clockwise direction for increasing the pressure,

and a reverse direction for decreasing the pressure. This operation is better

carried out while engine is running as it facilitates reading the Pressure Gauge.

Oil pressure to be set at 20 lbs. per square inch (30 lbs. for hot climates). If

Oil Pressure Indicator is fitted, push in the button and rotate screw until but-

ton projects. Oil pressure is then correct setting.

9.— OIL FILTER.—This is situated and is indicated by the Hexagon Cap

next to the Pressure Release Valve. After the cap has been unscrewed, the

Filter Tube and gauze can be withdrawn by inserting a finger in the orifice.

DO NOT DO THIS WITH THE ENGINE RUNNING.

10— The Oil Sump is separate from the Crank Chamber to facilitate the car-

rying of the Engine in any desired position without flooding the Cylinders

and Timing Case with lubricating oil. The Oil Sump can be replenished

while the Engine is running, if required.

11—. TO STOP ENGINE.-Press Magneto Earthing Button.

SPECIAL NOTES 12. TO RESTART ENGINE after it has warmed up it should not be neces-

sary to close the Air Strangler." B " or flood the Carburettor. Should the En-

gine fail to start, do not. close the Air Strangler as excess of petrol may be

deposited in the induction passage entrance, which will give too rich a mix-

ture for starting. In this event it is recommended that the Slow Running Con-

trol Knob " E" should be rotated to the right into its maximum position. This

operation does not give such a vigorous strangling as when using the Air

Strangler " B." When the Engine commences to run,, rotate the Knob " E " to

"the left until the Locating Ball is felt to click into position again. The move-

ment from " set running to " slow running " position is 180°.

ENGINE MAINTENANCE VALVE TIMING. —All four Valve Operating Cams are on a common Cam-

shaft. It is therefore only necessary to set one timing, the remainder being

automatically set.

NOTE.—The Timing Wheels are marked at the correct setting.

IGNITION TIMING.—Set at 4% before Top Dead Centre measured round

periphery of Flywheel in direction of rotation.

Top Dead Centre is marked on face of Flywheel for checking settings.

Top Dead Centre is marked " T.D.C.",Ignition is marked " IGN."

VALVE CLEARANCE.—.003" for Inlet Valve when cold. 004* for Exhaust

Valve when cold. ^

OIL FILTER.—Unscrew hexagon-headed Cap situated on

side of Crankcase underneath L.H. Cylinder. Insert finger and

withdraw Filter Tube. Clean thoroughly in petrol, taking care not to perfo-

rate gauze. Replace, and screw in Cap tightly. This should be done every

twelve hours of running approximately.

LUBRICATING OIL.—Unscrew Oil Filter Cap " A." Empty, Oil Sump.

Flush out Sump with clean oil, and fill up with recommended oil, about three

pints. Mobiloil B.B. is recommended for this engine. The Sump should be

cleaned and replenished with fresh oil every 50 hours of running.

Warning.- Do not use paraffin or petrol to flush out bump.

PETROL PIPE AND CARBURETTOR.—Unscrew hexagon head Filter

Screw from Carburettor end of Petrol Pipe. Withdraw gauze sleeve from Fil-

ter Screw. Clean gauze and wash out Screw in petrol. Unscrew Nut at Tap

end of Petrol Pipe and wash out Pipe with petrol. Open Petrol Tap and al-

low small quantity of petrol to flow through to wash out any foreign matter.

Remove Carburettor Float Chamber by taking out two square-head set

screws from top of Float Chamber cover. Hold Float Chamber in left hand

whilst doing this. When screws are removed, Float Chamber and main jet

stand will drop down and can be removed from main body of Carburettor.

The Float is loose in the Chamber. Carefully remove this. Carefully remove

brass Pilot Jet situated between Chamber and Main Jet and on a level with

top of Float

Chamber. Carefully remove Main Jet Cap by applying spanner to TOP

hexagon. Remove Main Jet. Thoroughly wash, with petrol, all foreign matter

from Float Chamber and petrol passages. Wash the two Jets and Jet Cap in

petrol. Jets must not be cleared of foreign matter by any method except blow-

ing air through them.

Any damage done to the Jets by reason of contact with a hard substance may

seriously affect the engine performance. Replace :1. Main Jet. 2. Jet Cap. 3.

Pilot Jet. 4. Float. 5. Float

Chamber to upper half of Carburettor. 6. Petrol Pipe to Carburettor with Fil-

ter Screw and Gauze. 7. Petrol Pipe to Tap.

SPARKING PLUGS.—Detach High Tension Leads from Plugs. Remove

Plugs and clean Points with brass wire brush. Adjust gap between Central

Electrode and Point to .020" by using feeler gauge, and pressing in or open-

ing out gap with small screw driver.

BREATHER PIPE.—Unscrew hexagon-head set-screw situated between

FlywTheel and Cylinder on left-hand side of Crankcase. Breather Pipe can

now be removed and should be cleaned together with screw, in petrol. Re-

place—screwing up nut fairly tightly.

TAPPET ADJUSTMENT—Unscrew knurled-headed screws and take off top

half of each Valve Cover. Adjust each pair of Tappets separately. Tappet

clearance must be adjusted with Valves closed. Flats are provided on Tappets

for holding with special spanner. Whilst holding each Tappet with spanner,

slack off hexagon nut immediately on top of Tappet. Now insert leaf of

feeler gauge, on spanner, between Tappet Adjusting Screw and Valve Stem

to ascertain whether clearance is too great or too small. By holding on Tappet

flats again with spanner and rotating hexagon-headed Tappet Adjusting

Screw, it is easily ascertained, by feel, whether the clearance is being opened

or closed. When the correct clearance is obtained, lock up the nut on to the

Tappet by holding the Tappet Adjusting Screw with one spanner and locking

up with the other. Check clearance as locked up.

MAGNETO (B.T.H.) A little attention given periodically about every three to six month will en-

sure satisfactory operation of the Magneto.

(a)— Contact Breaker.'

(i) —Remove the Contact Breaker Cover which is secured by a Spring Blade

attached to a Pillar.

(ii)— Lubricate the Cam Wick located in the lower part of the Cam Ring

with one or two drops of light machine oil and smear the Cam Track with oil.

Wipe off any surplus oil as this may find its way on to the Contacts and

cause misfiring.

(iii)— Slightly raise, and move to one side, the Contact Lever Retaining

Spring and allow one drop of oil to soak into the Wick in the Bearing Pin.

Remove

all surplus oil and replace the Retaining Spring.

(iv)— With the. Feeler Gauge provided on the Magneto Spanner, check the

contact gap when the Lever heel is on the high part of the Cam. Make sure

that the Gauge is quite clean before inserting between the Contacts. If the

gauge is very slack or very tight between the Contacts when they are fully

open, readjust, so that the s:au£e (0.012 in. thick) is just a comfortable fit.

Otherwise, do not interfere with the Contact Gap Setting.

If it is necessary to remove the Contact Breaker from the Magneto, unscrew

the centre screw with the spanner, when the Contact Breaker Assembly can

be withdrawn. When replacing make quite sure that the Feather Key on the

tapered boss of the Contact Breaker locates correctly in keyway in the end of

the Magneto Armature Shaft.

(b)— Cleaning high-tension components. The components in the high ten-

sion circuits of the Magneto should be examined and cleaned as follows :—

(i)— Remove the Collector or Pick-up Mouldings and wipe over with a clean

cloth moistened with petrol, to remove dust, carbon, or oily deposits.

Examine the Carbon Brushes to see that they move freely in the Brush

Boxes. Do not remove the Brushes unnecessarily. If it is required to

withdraw or replace a Brush, turn it in a clockwise direction and pull out

gently. This tends to wind up the Spring and free it from the sides of the

Brush Box, thus avoiding undue extension of the Spring which would alter

the Brush pressure.

To remove oily or carbon deposits from the Slipring Track or Flange (on the

Armature) insert a corner of a clean cloth in the Pick-up Aperture and press

lightly against the Slip-ring Flanges whilst slowly turning the Engine or

Magneto Shaft. Do not use any implement to exert pressure

with the cloth as this may result in damage to the Slip-ring.

(c) —Location of Faults.

If the Engine fires irregularly and faulty ignition is suspected as the cause,

examine the ignition system for the following defects

(i) —Ascertain that the short-circuiting device is functioning satisfactorily.

To do this remove the Contact Breaker Cover when, if this device is at

fault, Engine operation should be satisfactory.

(ii)— H. T. Cable loose, detached, or insulation perished. In the case of

Braided Cable, examine for faulty braiding and consequent breakdown of the

inner insulation.

(iii)— Sparking Plugs: Gaps too large, correct gap 0.02 in.

(iv) —Contact Breaker: incorrect contact gap setting, oil or dirt on contact

faces. To clean or trim up Contacts, use dead smooth file or oil stone.

(v)— High tension components: (a) Carbon Brushes sticking, (b) carbon or

oily deposits on the molding surfaces, (c) Brushes worn too short.

If this examination does not locate the fault and the trouble is not due to

other causes apart from ignition, the Magneto should be examined by a quali-

fied repairer.

MAGNETO (WICO) INSTALLATION.—When installing the Series "A" WICO Magneto on a

base mounted application, care should be taken to see that there is a proper

alignment between the driving members and the lugs of the magneto drive

cup. Before tightening the screws firmly this alignment should be checked by

cranking the engine, at the same time ascertaining that the float member has

sufficient play endwise during every turn of the cycle.

TIMING TO IMPULSE SPARK.—When the impulse sparkis to be used in

timing the magneto to the engine, and in the absence of other information

from the engine manufacturer, first remove the distributor cap. Then turn the

magneto shaft over in the proper direction of rotation until the impulse cou-

pling has just tripped.

Note which tower of the distributor cap the distributor arm is

nearest and the cylinder to which this tower is connected by the spark plug

cable ; then turn the engine over to top dead centre on this cylinder, on the

compression stroke, and-couple the magneto to the engine.

TIMING TO ADVANCE SPARK.—Where the engine flywheel is marked with the position of advanced or running spark, a different procedure is fol-

lowed.

For multi-cylinder engines, turn the magneto shaft in a direction opposite to

its ordinary rotation until the distributor arm is at the tower of the distributor

cap to which is connected the spark plug cable leading to cylinder number

one. By means of a thin piece of paper between the points, the exact instant

of breaker opening can be determined. At this point the magneto is in posi-

tion where a spark will be delivered to cylinder number one. Turn the

engine over until the advance spark mark on the flywheel is correctly located

on the compression stroke of cylinder number one and couple the magneto in

this position.

BREAKER POINT OPENING.—The breaker point opening should be ad-

justed to .015", by means of the screw head eccentric acting on the fixed con-

tact. Admission to the breaker box is accomplished by removing the distribu-

tor cap and the gear housing on multi-cylinder machines, and by taking off

the breaker box cover on the single cylinder.

IMPULSE COUPLING. —The impulse coupling is designed to give a spark of high intensity for starting. It automatically cuts out at about 165

KPM. The engine should not be run continuously below this speed, as this

would cause an unnatural strain and wear on the impulse parts.

The impulse also provides a retarded spark for starting, automatically ad-

vancing it as the engine gets up to speed. Any advance from 5° to 36° be-

yond impulse spark can be obtained by shifting the position of the impulse

stop from one to another of the three holes in the end plate. The end plate as

a whole may be shifted in its mounting slot to provide intermediate ranges

between the holes.

FLUSHING OF IMPULSE.—If the impulse becomes clogged with dirt, the necessity for flushing it is evidenced by the trip arms failing to engage or dis-

engage, or by sluggishness in the action of the impulse when it trips. The im-

pulse should be flushed out thoroughly with paraffin, taking care, however,

not to allow any of the paraffin to work its way into the magneto housing.

When a dust cover over the impulse is provided on the magneto, it must first

be removed by loosening the clips at either side.

LUBRICATION.—The magneto is provided with two spring oilers, one on each side of the main housing, so that whichever way the magneto faces the

engine, one oiler will always be convenient.

Once every two hundred hours of operation, these oilers should be filled to

overflowing with Castrolite. On multi-cylinder engines it is necessary to lu-

bricate the distributor gears in a similar manner after every 1000 hours of

service by removing the oil plug located just below the distributor cap.

After every 1000 hours of service it is necessary to re-lubricate the cam oil

pad. This is done by removing the pad and squeezing and working into it,

some stringy grease. A summer grade of automobile transmission grease will

very closely resemble that used at the factory. Do not use ordinary grease,

REMOVAL OF MAGNETO COVER.—Pull out the secondary interlead from the cover terminal, loosen the four screws holding the cover to the main

housing and pull off the cover.

REMOVAL OF COIL.—With the magneto cover off and the breaker box exposed, loosen the screw holding the primary lead to the condenser case in

the breaker box. Straighten the curved end of this primary lead so that it will

draw through the opening in the housing provided for it. Remove the two

screws holding the core clamps with their lock washers. Turn the rotor of the

magneto over until the magnetism no longer grips the coil core to the main

housing. Pull the coil and the coil core free. If the coil is to be replaced with

a new one, this is held on the coil core by a wedge, and it will, therefore, be

necessary to press with considerable force to remove the same from the core.

If the coil is being removed for testing, great care should be exercised during

this operation, in order to avoid damage to the winding. In replacing the coil

and coil core be sure the ground surface of the core is against the housing,

that the primary to condenser lead is properly located and that the primary

ground lead is fastened under the coil core clamp screw.

REMOVAL OF CONDENSER.—When the breaker box exposed by re-moving the gear case in a multi-cylinder machine by taking off the breaker

box cover in the case of a single cylinder magneto, take out the screw hold-

ing the primary and ground lead to the bakelite condenser. The entire breaker

box may then be removed by unscrewing the two fillister head screws at ei-

ther side of it, holding it to the main housing. The condenser is then taken

from the box by removing the two fillister head screws fastening it down. In

replacing the breaker box be sure the locating mark at the top is lined up with

the corresponding mark on the magneto housing.

REMOVAL OF DISTRIBUTOR.— Wedge the distributor clips out with a screw driver and pull the cap off. The distributor arm can then be pulled di-

rectly off its stud. The cap should be free of any dust or dirt before being re-

installed.

REPLACEMENT OF BREAKER POINTS.—It is recommended that if the points need replacing, both the fixed and moving points be replaced at the

same time. The breaker arm is integral with the spring and spring terminal

and the moving contact point. To remove it, take off the breaker arm clamp

screw, lock washer and clamp washer and the breaker arm spring terminal

screw and lock washer and pull the assembly off the breaker arm pivot.

In re-assembling, be sure that the steel breaker arm spacer is in place.

With the breaker arm assembly off, the fixed contact plate may be taken off

the breaker arm pivot, after the fixed contact screw has been removed.

FAILURE TO START AND LACK OF COMPRESSION 1—. Petrol Tank empty.

2.— Air lock in petrol system. Unscrew hexagon-head Filter Nut from Car-

burettor. Slack off and allow a small quantity of petrol to run through pipe to

clear air lock. Tighten Filter Screw. Air hole in Petrol Tank Filler Cap may

be blocked with foreign matter.

3.— Dirt in Carburettor. Clean out as per previous instructions.

4.— Fouled Sparking Plugs. Remove Plugs and clean Points with brass wire

brush. Wash out with petrol. Attach Plug to H.T. lead and earth same by lay-

ing on cylinder barrel and turning starter handle. If Plug does not spark, try

new one. If still no spark, remove Contact Breaker Cover from Magneto and

check gap between Points fully open. These should admit feeler gauge on

Magneto Spanner. Clean points by inserting a piece of paper between them

when closed and move backwards and forwards.

Clean Cam Ring by wiping round with a petrol-moistened cloth. Lubricate

Cam Ring with an oil-moistened cloth, taking great care not to allow any oil

to be deposited on points.

5.— Choked Exhaust Silencers.

6—. Lack of compression caused by insufficient Tappet clearance. Adjust

as per previous instructions.

7.— Cylinder Heads not tight or Gaskets defective. Try each Cylinder Head

nut for tightness. All these nuts should be equally tightened to prevent Cylin-

der Head distortion.

8—. Dirt under Valve seatings. Usually this can only be cured by removing

Valves and cleaning seatings on Valves and in Cylinder ports.

9—. Sparking Plugs loose, tighten up. All other causes of failure to start

should be investigated by a competent mechanic.

DECARBONISING 1. Remove high tension leads from sparking plugs.

2. Remove sparking plugs.

3. Unscrew seven special nuts from each cylinder head (R.H. thread).

4. Carefully remove cylinder heads, taking care not to damage gaskets.

5. Remove cylinder head gaskets.

6. Clean carbon deposit from inside of cylinder heads and both gaskets.

7. Care should be taken not to distort the gaskets in cleaning, and it is recom-

mended that fine emery cloth should be used for finally cleaning the com-

pression spaces and both sides of the gaskets. Wipe away all traces of em-

ery powder.

8. Carefully clean and polish the crown of the pistons.

9. Remove two knurled head set screws which secure the two halves of the

valve cover together.

10. Take off the top half of each valve cover.

11. Remove valves from cylinder, noting carefully that they are to be re-

placed in the same position when assembling.

12. Clean carbon deposit from combustion space in top of cylinder, taking

care not to damage valve seats.

13. Smear a small quantity of valve grinding paste on each of the valve seats,

and replace valve, rotating same in cylinder. The valves should be rotated

backwards and forwards until the seating is uniform width all round the port.

14. The valves should now be cleaned carefully, so that all trace of paste is

removed, and replaced in the cylinder.

15. The gasket is to be replaced on cylinder after both sides have been treated

with liquid shellac. (A suitable jointing compound such as " Osotite " is pref-

erable).

The above instructions do not cover the decarbonising of

Piston Rings and Grooves, etc.

Front View showing H° gallon Fuel Tank mounted on Engine and Pep-

per

Pot Type Exhaust Silencers. Specification V.