Sunbeam ALPINE I SERIES: APLINE II SERIES, Workshop Manual

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WSH. 124
Section C (Fuel System)
4. Screw in front carburettor throttle stop screw
(2) until it just touches its abutment as the
throttles are held closed; then screw in a fur­
ther 1½ turns in a clockwise direction.
5. Screw In the volume control screw (1) or the
slow running air control screws (4) by hand.
A screwdriver must not be used as It would
damage the screw seatings. Screw back screw
(1) three-quarters of a turn or screw (4) one
and a quarter turns in an anti-clockwise
direction.
6. With the engine warmed up to its normal
operating temperature adjust the control
screws (1) or (4) on the front carburettor to
give the smoothest possible idling. Then adjust
the rear carburettor in a similar manner. Re­
adjust front carburettor if necessary. Rotation
of screw (1) in a clockwise direction weakens,
and anti-clockwise rotation enrichens the slow
running mixture. Rotation for the screw (4)
is exactly opposite.
7. If Idling speed is now Incorrect, increase or de­
crease speed as required by adjustment of the
front throttle stop screw (2). This correction
of idling speed may require slight re-adjustment
of the screws (1) or (4).
Idling speed must always be adjusted by the
throttle stop screw (2) and idling 1)11Xture by
the screws (1) or (4).
8. The correct slow running speed for a HOT
engine Is 750 to 850 r.p.m. with the slow run­
ning mixture set just off of the rich ("hunting")
condition.
When the slow running is correct, adjust the
rear carburettor slow running throttle stop
screw (2) until it just touches its abutment.
This must be very carefully carried out. The
screw must actually touch the abutment but
not so hard as to increase the slow running
speed.
A final check of the slow running should be
made after replacing the air cleaners.
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9. After the slow running is correct a check must
be made to ensure that under full throttle con­
ditions the rear carburettor does not reach its
full throttle stop, before the front carburettor.
If this occurs undue strain will be placed on the
throttle coupling which can upset throttle syn­
chronisation. The full throttle stops on the rear
carburettor can be filed if necessary.
10. If "hesitancy" occurs when accelerating under
traffic driving conditions, it is an indication that
the carburettors are not properly synchronised.
Synchronisation can be checked by holding a
suitable length of carboard tubing over each car­
burettor intake, after removing the air cleaners
and listening for the "progression hiss" as the
engine speed is increased from idling to about
1,000 r.p.m. Both carburettors should make the
same sound which is quite distinct to hear.
If necessary the clamping bolt (3) can be
loosened off and the throttles adjusted to
obtain this condition.
After retightening the clamping bolt (3) it is
important to ensure that both throttle screws
(2) come against their abutment when the
engine is idling.
11. A very useful and inexpensive gauge known as
the "Synchro-Test" can be used to balance the
carburettors. This gauge saves a lot of time and
may be obtained under reference number B.91
from:-
Crypton Equipment Limited,
Bridgwater, Somerset, England.
Full operating instructions are supplied with
each gauge.
Throttle, fast idle for starting (See Fig. 16)
This adjustment ensures that the throttle is open
to the best position for cold starting when the
strangler is fully closed and can only be made with
carburettor removed from the engine.
To make this adjustment slacken the set screw on
the fast idle rod connection on the strangler-