According to Haynes SU manual:

1 Set the throttle adjusting screw. Run the engine to working
temperature, then switch off.

2 Where necessary, remove the air cleaner or plenum chamber.

3 Unscrew the throttle adjusting screw until it is just touching its
stop with the throttle valve shut.

4 Where applicable, check that the cold start lever is fully closed
(cold-start device out of action), and that the fast idle adjusting
screw is well clear of the cam. Failure to observe this may result in
the throttle being held open when, by external examination, it appears
closed.

5 Turn the throttle adjusting screw 1 1/2 truns clockwise to set the
throttle to its initial position.

6 Set the jet height. Remove the suction chamber and piston with
reference to Section 9. ( I'm not going to type Section 9 buy the
book)

7 Check that the needle guide is flush with the bottom face of the
piston.

8 Turn the mixture adjustment screw until the top of the jet is flush
with the top of the jet guide. Now turn the screw 2 turns clockwise.
If the mixture adjusting screw is covered by a small blue or red
tamper proof plug, hook this out with a small screwdriver and discard
it.

9 Refit the piston and suction chamber, together with the damper, with
reference to Section 10.

10 Set the idle speed and mixture. Refit the air cleaner or plenum
chamber. Note that where these items conceal the carburettor
adjustment screws, do not refit them but position them near the
carburettor and reconnect the vacuum hoses.

11 Connect a tachometer to the engine, and a CO exhaust gas analyser
to the exhaust tailpipe. if the exhaust gas analyser is not available,
it will not be possible to adjust the mixture setting accurately,
although a reasonable adjustment may be possible.

12 Run the engine at a fast idle speed until it reaches its normal
operating temperature. Where an electric cooling fan is fitted, this
must have started and stopped at least once. Continue to run the
engine for a further five minutes before commencing adjustment.

13 Increase the engine speed to 2500 rpm for 30 seconds and repeat
thisi at three-minute intervals during the adjustment procedures. This
is necessary to clear both the inlet manifold and exhaust system.

14 (electronic stepper motor instructions deleted)

15 If the cooling fan is running, wait until it stops, then turn the
throttle adjusting screw to give the desired idle speed. (electronic
carb. instructions deleted)

16 (electronic carb. instructions deleted)

17 With the engine idling, slowly turn the jet adjusting (mixture)
screw clockwise (to enrich)  or anti-clockwise (to weaken), until the
fastest idle speed which is consistent with even running is obtained.
Now slowly turn the scew anti-clockwise until the engine speed just
begins to drop. If an exhaust gas analyser is being used, adjust the
screw to obtain the desired CO percentage reading (typically 2.5 +or-
1.0%).

18 Reset the idle speed if necessary, then switch off the engine.

19 Set the fast idle speed (manual choke carburettors). Pull out the
choke control knob until the arrow on the fast idle cam is aligned
with the fast idle adjusting screw.

20 Start the engine and check that the fast idle speed is as desired
(typically 1100 to 1300 rpm). If neceassary, turn the fast idle
adjusting screw to obtain the correct speed.

21 Switch off the engine, and push in the choke control knob. Make
sure that the mixture lever is fully returned, and the choke cable
correctly adjusted.

22-26 (electronic carb. instructions deleted)

27 On all models, refit the air cleaner or plenum chamber where
applicable, then make a final check that the idle speed and mixture
are correct.

Cheers,

Kelley