MG Magnette KA Instruction Manual page 39

Coil.-The coil unit is not adjustable i n any way, and requires no attention
beyond seeing that the terminal connections are kept tight, and t h e moulded coil
t o p is kept clean.
W a r n i n g Lamp.-A warning lamp is provided i n the instrument panel, which
gives a red light when the ignition is
"
ON "
and the car is stationary.
The
warning lamp w i l l also light when the engine is running very slowly, due t o the fact
that t h e dynamo is not running at sufficient speed t o generate a high enough voltage
t o actuate the cut-out.
T h e D e t e c t i o n a n d R e m e d y o f I g n i t i o n Faults.-If a failure o f ignition o r
misfiring occurs, unless the cause is at once apparent t h e owner is strongly recom-
mended t o proceed i n accordance w i t h the following routine, which should quickly
enable him t o locate t h e trouble.
Before proceeding w i t h the examination, make sure that the trouble is not
due t o defects i n t h e engine, carburetter, petrol supply, sparking plugs, etc.
E n g i n e
will
n o t Fire.-Switch on t h e ignition, t u r n the engine and observe
the ammeter reading. The engine should be turned by hand i f it is known that
the battery is i n a l o w state o f charge.
I f an ammeter reading is given which rises and falls w i t h t h e closing and opening
o f the contacts, then the low-tension wiring is i n order. If the reading does not
fluctuate in this way, a short i n the low-tension wiring is indicated, o r the contacts
are remaining closed. W h e n no reading is given, a broken o r loose connection i n
t h e low-tension wiring is indicated, o r t h e battery may be exhausted.
Examine the high-tension cables, i.e. cables from t h e coil t o t h e distributor,
and from t h e distributor t o t h e plugs. I f the rubber shows signs o f deterioration
o r cracking, t h e cable should be renewed. Remove the distributor moulding and
examine the contacts ; i f necessary, clean them as described on page xxxi.
T u r n
t h e engine over by hand, and see that the contacts come together.
If a fault is indicated in t h e low-tension wiring, examine the cables from t h e
switch o r junction box t o coil, and from coil t o distributor. See that the battery
terminals are tight and that the cables from the switchbox t o the battery are secure.
The battery may be dismissed as the cause o f the trouble i f the lamps w i l l light.
Test the coil independently o f the distributor as follows :-Remove the cable
from the centre distributor terminal, and hold
it
about
$
in. from some metal part
o f t h e chassis and t u r n the engine. The sparking should be strong and regular i f
t h e coil is functioning correctly.
M i s f i r i n g a n d B a d Starting.-Examine t h e high-tension cables and the plugs.
If necessary, adjust the gaps t o the correct setting (about
20
thousandths o f an inch).
Sooty o r oiled plugs may be dismantled and washed out w i t h petrol.
The plugs and high-tension cables may be tested by removing the plugs i n t u r n
and allowing them t o rest on the cylinder head and observing whether a spark occurs
at the points when the engine is turned by hand. I t should, however, be noted
that this is only a rough test, since
it
is possible that a spark may not take place when
t h e plug i s under compression.
Remove the distributor moulding and see that t h e electrodes and contacts are
clean. I f necessary, clean them as described on page xxxi. See that t h e contact gap
setting is correct.
If after carrying o u t t h e examination suggested, the trouble cannot be found,
we advise that the equipment should be examined by t h e nearest Lucas/Rotax Service
Depot, t h e addresses o f which are given later.
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