CARBURETTERS N OTE.~On dust-proofed carburetters, identied by a transverse hole drilled in the neck of the suction chambers and no vent hole in the damper cap, the oil level must be a} in. below the top of the hollow piston rod. (2) Warm up the engine as described in Tuning conditions. Turn the throttle adjusting screw until the idling speed given in TUNING DATA is obtained. (3) During the following prbcedure, just before the readings of the tachometer and exhaust gas analyser are taken gently tap the neck of the suction chamber with a light non-metallic instru- ment (e.g. a screwdriver handle). Turn the jet adjusting nut up to weaken, down to richen, until the fastest speed is recorded on the tachometer. Turn the jet adjusting nut very slowly up (weaken) until the engine speed just commences to fall, then turn the nut one at down (rich). Check the idling speed against the gure given in TUNING DATA, and adjust if necessary using the throttle adjusting screw. SET JET RESTRICTOR HERE ENGINE SPEED JUST COMMENCING TO FALL ENGINE . RPM. -4 -3 -2 -1 . +1 +2+3 +4 JET ADJUSTING NUT-FLATS D 0476 (4) Using the exhaust gas analyser, check that the percentage CO reading is within the limits given in TUNING DATA. If the reading falls outside the limits given, reset the jet adjusting nut by the minimum amount necessary to bring the reading just within the limits. If an adjustment exceeding two ats is required to achieve this the test equipment should beelmelred for correct calibration. Engine Emission. Issue 3. 24062 427 (5) Hold the jet adjusting nut (1) to prevent it turning, and rotate the adjustment restrictor (7) round the nut until the vertical tag contacts the carburetter body on the left-hand side when viewed from the air cleaner ange (see illustration). In this position, bend the small tag on the adjustment restrictor down so that the restrictor locks to the nut and will follow its movements. Paint the small tag of the jet adjusting nut restrictor and the adjacent at of the jet nut to identify the locking position. (6) (7) Reconnect the mixture control wire (8) with ap- proximately 113 in. free movement before it starts to pull on the jet lever (9). (8) Pull the mixture control knob until the linkage is about to move the carburetter jet and adjust the fast-idle screw (4) to give the engine fast-idle speed (9) Check and if necessary adjust the throttle damper setting-if tted (see TUNlNG DATA). 4-11