MG Magnette KA Instruction Manual page 33

T o afford a richer mixture for slow-running, the jet adjusting nut should be
unscrewed.
By screwing the jet adjusting nut upwards, the petrol consumption can be
cut down i f the owner is satisfied w i t h a lesser degree o f acceleration and speed,
and sometimes i n hot weather general all-round better carburation can be obtained
by thus cutting down the petrol supply. Screwing up t o o much may cause popping
through too weak a mixture.
A
little machine oil should be injected into the dash-pot o r suction chamber
brass cover screw every thousand miles, t o lubricate the piston guide rod ; three
drops o f machine oil is advised for this purpose.
Under no circumstances should the body o f the suction disc o r piston be
lubricated.
By inserting t h e finger through the air inlet t o t h e carburetter, the piston
can be lifted inside t h e body o f the carburetter, and should rise and fall freely.
The use o f the strangler, or, as it is correctly called, t h e jet control, is intended
only for starting when the engine is cold, and should be employed as little as possible.
The effect o f using the jet control is t o enrich the mixture when starting. If
it
is
left in operation longer than is necessary the cylinder walls w i l l be bathed w i t h
surplus petrol, which will soon have a damaging effect on the pistons and other
parts o f the engine as well.
Reference t o Illustration No.
5
shows the jet control lever in position. The
jet adjusting nut is in point o f fact only a stop against which the jet head rests
when t h e jet control lever is pulled backwards, so that
it
stands t o reason that i f
any adjustment o f the jet has t o be effected, this has t o be carried o u t on each
separate carburetter. I t follows that as all the three jet control levers are coupled
up, and i f only one jet nut is unscrewed, unless the jet controls are slackened off
first, all the other carburetters will have been adjusted similarly t o any individual
one.
The t w o screws that hold the piston body in which the piston and suction
disc operate should be removed, so that the piston and its guide rod can be cleaned.
Extreme care should be exercised in removing the pistons, so as not t o damage
t h e taper jet needle in any way. Mark t h e suction chamber before removal and
replace
it
t h e same way as originally fitted. D o not change the suction chambers
from one carburetter t o another.
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