Untitled - The Triple

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Untitled - The Triple
You should take particular pains t o check the toe-In o f your front wheels, the correct
measurement being &" (7.9 mm.). T o carry out this adjustment, slacken the lock
nuts and adjust by the right- and left-hand threads which are provided. Should you
have occasion t o dismantle the rods, particular care should be exercised when reassembling t o make sure the springs behind the cups are fitted in the correct position.
This is most important and a careful study o f the Manual, which explains the point
fully, should be made (pages 16-18.) D o not forget that the triple steering arm which
pivots on the centre o f the axle beam and the steering knuckle pivot pins must receive
very frequent attention. A good quality grease, similar t o Duckham's HBB, should
be pumped into these parts until there are obvious signs o f grease leakage, particularly
at the lower end o f the steering knuckle pivot pins.
There is a tendency for nearly everyone t o adjust the shock absorbers much t o o
tightly, and on frequent occasions we find them locked solid, the inevitable result
being broken mounting brackets. This, in the middle of a race, is very bad indeed,
and may be serious. Therefore, adjust shock absorbers by small degrees only, and
t o make sure they are not over-tight, adopt the measures o f a very large number o f
the crack racing drivers. Jack the car up at four points on the chassis frame, leaving
the axles free, and i f the shock absorbers are correctly adjusted they should be just
tight enough t o hold the axle in any position, o r t o be more explicit, you should be
able t o lift each wheel and it should remain at the highest point. You should then
be able t o push the wheel down t o its lowest point, and it should remain there. This
is a good general rule t o follow. It may seem strange, but oddly enough we have
come across cases where mechanics o r owners have lubricated their shock absorbers !
O f course, on no account must this be done. If you are not satisfied that the absorbers
are working satisfactorily, renew the special discs. This, however, is rarely necessary.
The front axle torque cables should be checked for adjustment occasionally. W i t h
the car in a stationary position the free movement in the centre o f the cable should
be i"(9.5 mm.).
The only warning necessary i n regard t o the pre-selector gearbox, and this warning
cannot be sufficiently stressed, is that gear changes must not be made without use
o f the accelerator in exactly the same way as w i t h the normal manual box. Any
attempt t o change down from a high t o a lower gear without increasing the engine
revs., o r changing up without a slight pause, will most certainly result i n transmission
damage, and although a gear can be pre-selected at any time, a corresponding variation
in engine speed must be made when actually changing, o r as nearly so as possible.
Another very important point we wish t o bring t o your notice, should you for .any
reason wish t o t o w the car, always disconnect the propeller shaft, otherwise there
i s every possibility that damage t o the box will result, since the gearbox oil pump
is engine driven. This is importaot. Furthermore, we wish t o emphasise the importance o f using the correct lubricant in the gearbox. This should be Duckham's N.P.3
o r Wakefield's Castrol " F." The adjustment o f the gearbox is a specialist's job, and
you are well advised, should it give you trouble, t o communicate direct w i t h the
Factory, o r w i t h the makers, Messrs. The E.N.V. Engineering Co., Ltd., 415 Hythe Road,
Willesden, London, N.W. 10.
D o n o t forget that the Hardy Spicer joints on the propeller shaft require
lubrication ; special grease for this purpose is Duckham's Hardy Spicer Grease, obtainable either from the makers o f the shaft o r the Factory. Ordinary grease most
definitely will not do, it must be a centrifugal non-separating grease. The propeller
shaft is very carefully balanced up t o 7000 r.p.m., and should you, by misuse of the
pre-selector box, o r otherwise, over-stress the transmissio~~,
you may put the shaft
Page Four
.
out of balance. This i s indicated by a general roughness a t speed, and should this
condition arise, immediately have the propeller shaft replaced or rebalanced, otherwise
serious damage may result in the use of a racing car at speed with the propeller shaft
out of balance.
Care must be taken when running at high speed not t o throw the gearbox into
neutral suddenly. If, when cutting t o examine plugs, etc., the clutch pedal is held
right down until the car has reached a fairly slow speed before selecting neutral, trouble
will be avoided.
,
Brakes. As the design of these brakes i s novel and should be thoroughly
understood, a somewhat lengthy description is given here. Particular attention
should be made to'method of adjustment.
The brakes are arranged 50 that the smallest possible load on the cables produces
the maximum possible braking effort. To do this, t w o cam levers are used, one
operated by the inner cable and the other by the outer casing, an arrangement which
exactly doubles the force of application for a given cable load. The cams which operate
the brake-shoes take the form of rollers which roll against each other back t o back
under the load, thereby reducing the friction t o a negligible value.
The cable load on the levers i s also taken by a pair of rollers mounted in a dustproof housing on the back plate, packed with grease. These have the same effect as
the' cam rollers in reducing frktion.
To ensure that both shoes always press equally against the drums, a centralising
link is fitted which moves about a centre having a tight friction grip. ~ j l i scentre is
difficult t o move, but the heavy forces from brake application move it quite easily,
thereby bringing the shoes central with the brake-drum at the f i r s t application of
the brakes.
44
Brake adjustment takes the form of a wedge expanding the heels of the shoes
apart. A take-up is provided in the cockpit, enabling limited adjustment t o be made
if necessary. as for example during a race ; but this i s only a provisional measure, the
main adjustment being on the brake back plates.
If the foot brake pedal is getting too near the floorboard, i t is only necessary t o
take up the adjusters one or t w o clicks each, when the brakes will be found t o be
adjusted quite eveniy.
To ensure that the brake-shoes make their first contact with the drum in a perfectly
true movement, small fibre steadying blocks are provided which steady the shoes and
prevent them from rattling or moving sideways.
I t should be noted that only a very small amount of brake adjustment can be
effected in the cockpit. I t will be obvious when the gear is examined that considerable
adjustment at the cockpit control will only result in reducing the available movement
of the cams.
The correct method of adjustment is t o work almost entirely on the adjusters
on the brake back plates. These are set correctly when the car leaves the Works,
and it will be found that they can be turned by slow degrees, each quarter turn producing
a definite click. This renders it possible t o obtain exactly similar adjustment on each
wheel.
Page Five
W h e n other than mlnor correctlon is necessary, the cockpit adjusters should
be slacked right off, and the above-mentioned back plate adjustments carried out.
W e must stress the importance o f suitably lubricating the brake cables and
casings : quite often we inject a syringe o f engine oil t o make sure that they w o r k
freely, followed, o f course, w i t h an application o f thicker gear oil. W h e n carrying
o u t this operation, make sure that the brakes are in the " on " position, as this holds
the end o f the casing tight against the stop, and allows the lubricant t o travel the
cable's length.
The petrol tank capacity is 2 7 i gallons (125 litres), fuel feed i s by electric pumps.
The great point t o bear in mind in connection with the fuel supply is that in no circumstances must a partial failure o f supply be allowed. This is particularly t o be guarded
against in the case o f pressure i f a hand pump is used. The minimum air pressure
permissible is 2 lb. and a failure in pressure will result in lean mixture. This will
cause pre-ignition, and such a condition must be followed by damage t o the engine.
A cracked head will very frequently be the result o f a few minutes' driving w i t h
insufficient petrol in the carburetter.
W h i l e considering the hand pump again, d o not w o r k this w i t h unnecessary
vigour. The results, from the point of view of tank pressure, will not be improved,
and over-energetic use o f the pump may quite easily damage the gauge.
In view of the damage which can be wrought, no apologies are made for reiterating
this instruction. D o watch your air pressure and dbn't risk a lean mixture.
There is very little likelihood o f starvation t o the carburetters when using electric
fuel pumps, but should partial starvation occur from this cause, one o f the first
indications would be an explosion via the explosion valvz.
In passing it may be observed that an alcohol fuel should not be left in the tank
for any length o f time when the car is o u t o f use. Before putting the car away the
petrol tank, carburetters and all the pipe lines snould be carefully drained. W e
consider this an important point, as otherwise there is a likelihood o f trouble w i t h
thesc parts.
W i t h regard t o the facia board instruments, these are quite straightforward.
but be careful not t o leave the Ki-gas injector turned on. As a matter o f fact, experience
has shown that it is very seldom necessary t o use it. W h e n a car has been standing
for some time a couple o f pumps on the injector will be sufficient, after which it must
be screwed right home again.
The supercharger pressure should be between I 0 lb. and 12 lb. There is an o i l
pressure gauge in connection w i t h the oil feed t o the supercharger, and whilst 2 lb.
t o 4 lb. i s an average, watch this carefully, as below I lb. there is a danger, and the
feed should. be checked over immediately, as the result o f insufficient oil fed t o this
unit may result in seizure of the supercharger. The water temperature should not
exceed 90" centigrade and the oil 80" centigrade.
Considering the engine, note again, for entry form purposes, that the bore is
57 mm., the stroke 71 mm. and the capacity 1087 C.C. The compression ratio 6.4 and
the maximum r.p.m. 6500.
a
Page Six
1
Engine lubrication is quite straightforward, t h e sump carries approximately 2
gallons (9.1 litres) and the reserve o i l tank 2 gallons (9.1 litres). W e fit a float-chamber
attached t o t h e sump which automatically maintains the engine o i l level. This oil
is fed f r o m the reserve tank, b u t periodic checking that t h e reserve o i l flows freely
t o t h e sump is advisable, and w e usually check this when renewing t h e engine oil by
putting only I gallons (6.8 litres) in t h e sump and allowing the additional half-gallon
t o flow through f r o m t h e reserve tank. W e recommend that this is always done.
W i t h regard t o the Tecalemit filter, note that absence o f a really tight joint here
w i l l cause trouble. The Tecalemit o i l filter is readily replaceable, and it is important
that a new filter element is fitted f o r every race. Should t h e filter element become
choked f o r any reason, one o f the first indications will be a d r o p i n t h e oil pressure.
Further, when changing t h e filter, care should be taken t o clean t h e whole o f t h e filter
bottle, and it is necessary t o remove t h e filter bottle f r o m t h e engine f o r this purpose.
Generally speak~ng,castor base oils, i.e. Castrol " R," Shell Super Heavy, Pratts'
Racing, etc., are accepted by long experience as being t h e best racing oils. These
oils, however, should invariably be drained while the engine is still warm, and fresh
o i l substituted,.for the next racelheeting. For everyday use mineral oils alone are
suitable, as these, o f course, may be left i n the engine i n the ordinary way. Some
drivers are actually using mineral oils for racing, such as Duckham's Special N.P.5
Aero, Essolube, Castrol XXL, etc., w i t h a considerable measure o f success, b u t until
more experience has been gained, it is preferable that castor base oils should continue
i n use far long-distance track racing.
Valve Gear Adjustment. The correct rocker adjustment is .015" o n t h e
exhaust and .008" on t h e inlet. This measurement should be taken between t h e cam
and t h e heel o f the rocker, the position is illustrated i n the Manual. Particular care
should be taken over this. Also, when tightening u p t h e rocker pinch bolt which
fixes t h e eccentric bush, if a long spanner is used distortion and tightness is likely t o
occur, therefore always use the short spanner-3" o r 4" long-which is provided, and
carefully check afterwards t o make sure that the rocker is perfectly free.
Valve Timing and Ignition. This is fully explained i n the Manual, therefore
w e d o n o t propose t o include it i n these preliminary notes. As explained i n t h e
Manual, there is very little w e can discuss w i t h advantage relative t o valve t i m i n g once
it is carefully set, but you may be able t o get variations i n performance by slight
adjustment o f t h e ignition.
First o f all carefully watch the contact points and make sure that they are clean.
Burning and pitting conditions would indicate a weak condenser, and this should
immediately be renewed. The correct gap setting at the contact points is .012".
Another point that should be watched is t h e attachment o f t h e high-tension leads
t o t h e distributor itself. Keep them free f r o m moisture and oil, and frequent examination is advisable t o detect breaks i n t h e insulation, because it is o u r experience
that these details are often overlooked and can be t h e cause o f mysterious misfiring.
Engine Speed. W h i l s t t h e engine w i l l actually exceed t h e figures given, it
is n o t desirable t o go above t h e following f o r normal long-distance races :5500 o n first and second.
6000 t o b i 0 0 o n t h i r d and top.
Page Seven
For short events o r hill climbs up t o a mile :6000 on first and second, and
6500 on t h i r d and top.
Revolutions du Moteur. Bienque le moteur puisse surpasser actuellement
les revo!utions donnees ci-dessous, il n'est pas desirable d'exceder les suivants pour
les courses de grandes distances.
5,500 revolutions en premiere e t deuxieme vitesses.
6,000 revolutions en troisieme e t auatri6me vitesses.
Pour epreuves courtes, ou courses de c6te, jusqu'8 une mille.
6,000 en premiere e t d e u x i h e vitesses.
6,500 en troisieme e t q u a t r i h e vitesses.
Obviously w i t h regard t o engine revs the most important condition t o avoid
Is valve crash. The r.p.m. at which valve crash occurs varies w i t h different engines,
but it is usually somewhere after 6500 r.p.m.
O n no account crash your valves.
Fuel. Broadly speaking t w o types o f fuel are available. Alcohol mixtures
benzole mixtures. It is
-frequently
referred t o as " dope " o r " fuel "-and
absolutely imperative that no fuels should be used under any circumstances save
those approved for use in an M.G. Magnette K3 by the petrol company supplying.
Alcohol fuel makes a considerable difference t o consumption, being something
like 40 per cent. higher. The water temperature is not affected t o any great extent,
but o i l temperature may be reduced by something' like 10 degrees centigrade. I t
should be observed that suitable carburetter adjustments are necessary w i t h varying
fuels. As a rough guide, benzole mixture requires an RM needle, while the use
o f alcohol calls for an RM2 o r an RM3.
Although each engine has received prolonged bench tests the car should n o t
be raced until 500 miles has been covered. The handling o f the car in its early life
is o f the utmost importance, and strict compliance w i t h the following routine is
advisable.
The engine as it leaves the Factory is tuned for a mixture o f 80 per cent. benzole
and 20 per cent. ethyl petrol, with S.U. RM needle and i:;" jet. The blower oil
feed is correct as set at the Works, and should not be touched. For starting up
and running up t o a maximum o f 2000 r.p.m. K.L.G. LKS5's may be used. The
water temperature should not exceed 90" centigrade and the oil 80" centigrade.
After a hundred miles at 2000 r.p.m. the car should be looked over and checked
by plug inspection for lean mixture. They should show just a trace o f richness.
Another four hundred miles should then be covered at 3000 r.p.m., the plugs i n
this case being K.L.G. 718C's. A t the end o f each hundred miles the car should
be checked over.
W h e n the running-in is completed, the car checked over and the oils changed,
the following procedure should be adopted :Drain petrol tank and refill w i t h the r x i n g fuel decided upon. This w i l l call
for a different carburetter needle, RM2 o r RM3, and K.L.G. 689 plugs. W h e n warmed
up, complete a lap, o r three miles, w i t h maximum r.p.m. 4500.
C u t clean on full t h r o t t l e and stop.
when examined.
Page Eight
Plugs should then be i n a clean condition
Plugs should be examined t o c h e k up mixture strength and the engine looked
over. If the mixture i s approximately correct the plug points will show practically
no trace of burnt oil o r petrol, and will have a white appearance at the actual burning
points, whilst the surrounding body of the plug will be slightly brown. If the
mixture is too rich they will look wet or sooty. If too weak, the whole of the plug
will tend t o have the same whitish appearance mentioned before, and in addition,
there may be whiskers on the electrode and excessive burning, which has resulted
in a large gap. The standard gap i s .018" and should not be greatly exceeded at
any time. These tests should be repeated, increasing the r.p.m. 500 each time up
t o 6000 r.p.m. o r maximum. If everything i s satisfactory, carry out one lap at full
throttle, followed by the usual examination. Afterwards, and with the same
examination, complete t w o laps, or six or seven miles. Finally, give a 12-15-mile
(20-24
kilos.) all-out, again examining at the end of the run.
Almost as important as correct mixture i s theuse of the correct type of sparking
plug. An unsuitable plug will do just as much damage t o an engine as a lean mixture
or unsatisfactory oil.
As a rough guide, a soft plug must be used for starting and warming up, as for
example :Lodge HD14.
K.L.G. L K I o r LKSj.
When using plugs of this description do not exceed 2 lb. supercharge.
For road racing K.L.G. 718C or K.L.G. 690 may be used, the 690 being rather
harder, that is t o say, standing greater heat than the 718. For full-speed track events
use either the K.L.G. 690. 646 o r 689.
It is vitally important t o ensure that the plug used will stand up t o full throttle
before any attempt is made t o run the car all-out for any distance, the reason being
that the slightest pre-ignition would impose such loads on the engine that serious
damage may be done in a very short time, even t o the extent of cracking the head.
O n occasions i t is advisable t o remove the cylinder head t o carry out an internal
examination. This more than in any other way will give you considerable information, and a very direct reading as t o the correctness of your mixture and other
combustion factors. The appearance of the combustion chambers and valves is
usually the best evidence available as t o the condition of the engine from a combustion standpoint. If all is going well the inlet valves should all look alike, the
exhaust valves should all look nearly alike, and the carbon formation on the cylinder
heads should be generally similar on all six. Persistent misfiring on one cylinder
o r any other trouble of such nature will invariably be revealed by the appearance
of the head and exhaust valve of the cylinder concerned. Pratts M.G. I o r Shell
N.3 cause a grey-coloured deposit on the cylinder head ; this deposit i s quite
harmless. If any serious pre-ignition has taken place the heat and pressure may
have cracked the cylinder head between the valve seats. This, of course, will
necessitate either repair o r replacement, dependent upon the extent of the damage.
The head should, after examination of carbon, etc., be cleaned and again examined
generally from a mechanical point of view, valve grinding (the less the better), and
such-like operations being quite normal.
Very special valves indeed are used in these engines, and it i s frequently only
necessary t o give them a very light' polishing i n on the seats t o restore perfect
conditions.
"
.
Page Nine
W h e n reassembling valve gear t h e greatest possible care must be taken t o make
sure t h e circlip fits c o r r e c t l y i n t o its groove o n t h e valve stem. N e v e r use a c i r c l i p
cannot stress this
t w i c e : always fit a new one. It is o f m a j o r importance-we
A
n
experienced
mechanic
t o o highly-that t h e circlip fits snugly i n t o t h e groove.
can detect this q u i t e easily, b u t i f you have any doubts about it use a magnifying
glass, o r any o t h e r means t o make sure this fits correctly. Particularly should you
examine t h e c i r c l i p groove before f i t t i n g a circlip, because any sign o f t h e r o u n d i n g
o f t h e t o p edge, o r o t h e r distortions o r damage t o t h e groove, should be accepted
as an indication t h a t t h e circlip cannot possibly fit correctly, and t h e valves should
be replaced.
If t h e circlips are p r o p e r l y fitted i n accordance w i t h these instructions, you
w i l l never have o n e come adrift. If badly f i t t e d t h e y are almost certain t o fail.
W h e r e a steel gasket is used, as i n t h e case o f t h e standard compression, note
t h a t this m u s t be very carefully f i t t e d . In replacing t h e o l d gasket, after t h e head
has been removed, it is almost impossible t o fit it incorrectly, p r o v i d i n g it is a close
fit o n t h e dowels provided. You must v e r y carefully examine this, and make sure
t h e r e are n o b u r r s r o u n d t h e stud holes, deep scratches o n t h e faces, o r any o t h e r
damage. Y o u w i l l note, w h e n fitting, t h a t an allowance o f h-''(.8 mm.) is provided
r o u n d t h e combustion chamber. This is t h e c o r r e c t amount. Having ascertained
t h a t t h e gasket is i n good c o n d i t i o n and b o t h t h e face o f t h e head and t h e block are
also free f r o m damage, a t h i n layer o f gold size o n e i t h e r face o f t h e gasket is all t h a t
i s necessary t o ensure a sound joint. Particular care should be taken i n pulling t h e
head d o w n equally.
Should f o r any reason you find it necessary t o fit a n e w steel gasket, particular
care m u s t be taken i n l i r ~ i r ~itg up. T h e c o r r e c t procedure is t o lay t h e gasket o n
t h e head and fit t h e t w o d o w e l pegs i n t o t h e large holes at e i t h e r end. T h e n careful
measurements should be taken r o u n d t h e combustion space, and t h e gasket filed
t o give an equal & " (.8 mm.) clearance all round. W e w o u l d stress t h a t t h e d o w e l
pegs which you use f o r this purpose are a g o o d fit, b o t h i n t h e gasket and t h e cylinder
head. T h e purpose o f t h i s recess is t o p r o v i d e a suitable cavity f o r carbon deposit,
which helps considerably t o f o r m a gas-tight seal.
Should y o u experience any difficulty i n making a gas-tight j o i n t t h i s may be
due t o some peculiarity w i t h t h e face o f t h e cylinder block and t h e cylinder head.
It w o u l d be desirable t o have these lapped together, b u t t h i s operation can o n l y
be carried o u t by 2 real e x p e r t i n this t y p e o f w o r k , and w e w o u l d s t r o n g l y recommend
y o u o n all such occasions t o place this operation i n t h e hands o f t h o r o u g h l y e x p e r t
people.
T h e c o r r e c t clearance f o r connecting r o d bearing fit is .000" o n t h e diameter
and .004" side play, and care should be taken t o r e f i t t o these l i m i t s after r e metalling.
A l t h o u g h it may n o t be necessary, w e w o u l d p o i n t o u t t h a t these connecting
rods are re-metalled w i t h t h e highest possible grade o f metal specially suited f o r
racing, and o n n o occasion should l o w grade metal be used.
W h e n r e f i t t i n g piston rings t h e r e is a tendency t o have t h e gap much t o o fine.
T h e c o r r e c t clearances f o r piston r i n g gaps are :-.006"--.010".
Poge Ten
--
L
It may be useful t o note that the average temperature variation between alcohol
fuel and benzole is from 1 0 t o '15" centigrade, the alcohol running cooler. The
petrol consumption varies considerably with various fuels, the alcohol grades having
a consumption higher by something like 35 per cent. t o 45 per cent. in relation t o
petrol, the normal consumption of fuel being in the neighbourhood o f 8; t o 9 miles
per gallon. The use o f a benzole mixture would probably result in a consumption
o f 12 t o 13. When considering the possibility of lean mixture do not forget that
a leak in the blower would cause this, and this would be indicated by a fall in the
blower pressure. It could further be checked by dropping oil around the joints
o f the blower, and seeing i f it was sucked in. The fuel pump seldom gives trouble,
and i n such cases it i s advisable t o suspect air leaks. Under such circumstances the
pump would knock and investigation should be made immediately.
NOTE.-These
instructions are supplementary t o the Manual for the
M.G. Magnette K models (unsupercharged). The Guarantee
post card which accompanies this booklet should be filled in and
returned. On i t s receipt a t the Factory the Manual will be issued.
Page Eleven

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