MG MGA Twin Cam Workshop Manual page 103

Fig. D.9 The piston lifting pin
When both carburetters are correctly adjusted for mixture set the throttle adjustment screw of each to
give the required slow running. Adjust the link between the mixture levers so that each lever is moved
the same amount when the mixture control is used.
Slow running and synchronization
Turn the throttle adjustment screw of each carburetter to give a fast idling speed, taking care to turn
each screw the same amount. Next unscrew each throttle lever adjustment screw an equal amount, a
fraction of a turn at a time, until the desired slow-running speed is obtained.
Accuracy of synchronization can be checked by listening at each carburetter air intake in turn through
a length of rubber tubing and noticing if the noise produced by the incoming air is the same at both.
Any Variation in the intensity of the sound indicates that one throttle is set more widely open than the
other.
When the same intensity of sound is given by both carburetters the coupling shaft clip should be
tightened to ensure that the throttles work in unison.
Note that a small peg in one lever fits loosely in a hole in the other lever to form a connection between
the two spindles. When tightening the lever clamping nut make certain that the peg is located centrally
in the hole when both throttles are closed.
Since the delivery characteristics when both carburetters are working together vary somewhat from
those existing when each is working separately, it will be necessary to check again for correctness of
mixture strength by lifting each piston in turn as indicated in "Adjusting the jets' and adjusting as
necessary.
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