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• Cleaning and Regapping
Carefully' clean the spark plugs in an abrasive type cleaner. US,e a pin type feeler gauge to check spark plug gap. Reset gaps to specification. Before setting spark plug gap, file centre electrode flat, make adjustment by bend ing ground (side) electrode, never bend the centre electrode.
When installing spark plugs, tighten to specified torque.
Carburettor Idle Speed and Mixture
It is strongly recommended that a reliable exhaust gas analyzer and an accurate ignition tachometer are used when making these adjustments.
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• Procedure using tachometer and gas analyzer
(1) Warm up the engine by idling with engine hood up for 15 to 20 minutes. Ensure that choke is fully open.
NOTE: Vehicles fitted with BIAS must have an engine compartment temperature of at least 38°C (100°F) before any adjustments are made (i.e. snorkel flap valve fully open).
(2) Set the ignition timing to specification.
(3) Check that the air cleaner is fitted correctly. (4) Place transmission in neutral.
(5) Turn off all vehicle lights and air conditioner.
(6) It is important that the two idle mixture screws are both turned out the same amount from the seated position.
(7) Connect tachometer.
(8) Switch on the analyzer, allow it to warm up then calibrate according to manufacturers' instructions.
(9) Insert the probe of the gas analyzer in the tail pipe as far as possible.
NOTE: It is essential that the probe and connecting tubing of the analyzer are in good condition, as any leaks would lead to erroneous readings. If a garage exhaust system is used to conduct the exhaust gases away during the operation, it will be necessary to fit a plenum chamber (or other means) to reduce the vacuum of the system to a reading of 12 mm (l inch) or less on a water gauge.
(10) Set the idle speed to specification.
(11) Adjust the mixture screws to obtain a carbon monoxide level of 0.2 to 0.8% on all models except those with 8 cyl. man. trans. Eight cyl. man. trans. models should be set at 0.5 to 1.0% CO.
IMPORTANT: When setting the idle mixture do not tum the adjusting screws more than 1/16 tum at a time. The exhaust analyzer is so sensitive that the ratio must be changed by very small amounts if accurate readings are to be obtained.
(a) Adjust the mixture screws 1/16 tum richer (anti clockwise) and wait 30 seconds before reading the analyzer.
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(b) If necessary repeat step (a) until analyzer indicates a definite increase in richness. This step is very important since some analyzers (thermal conductivity type) reverse readings and indicate a richer mixture as the carburettor is set too lean.
(c) When it has been established that the analyzer is indicating a richer reading when the idle mixture screws are turned in the rich direction, proceed to adjust the car burettor to achieve a carbon monoxide level of 0.2 to 0.8% on all models except those with 8 cyl. man. trans. Eight cyl. man. trans. models should be set at 0.5 to 1.0% CO.
(d) If the idle speed changes as the mixture screws are turned, adjust the speed back to the specified r.p.m, then readjust the idle mixture to obtain above specified ratio.
(e) Race engine at 2000 r.p.m. for 5 seconds, then recheck idle speed and analyzer reading. Readjust if necessary.
(0 Increase idle speed to specified value if this differs from the mixture setting speed.
NOTE: As mixture screw is turned clockwise (leaner) air/fuel ratio increases and %CO de creases. As mixture screw is turned anti-clock wise (richer) air/fuel ratio decreases and %CO increases.
• Procedure using tachometer only
(1) Warm up the engine by idling with engine hood up for 15 to 20 minutes. Ensure that choke is fully open.
NOTE: Vehicles fitted with BIAS must have an engine compartment temperature of at least 38°C (100°F) before any adjustments are made (i,e. snorkel Bap valve fuDy open).
(2) Set ignition timing to specification.
(3) Check that the air cleaner is fitted correctly. (4) Place transmission in neutral.
(5) Tum off all vehicle lights.
(6) It is important that the two idle mixture screws are both turned out the same amount from the seated posi tion:
(7) Connect tachometer. Back off throttle kicker adjust ment (8 cyl. man. trans. with E.L.B.)
(8) Remove idle limit caps.
(9) Adjust idle speed/solenoid screw and mixture screws to best idle at X R.P .M. (refer chart).
(10) Without touching speed screw tum mixture screws clockwise (lean) equally to reduce speed to Y R.P .M.
NOTE: On eight cylinder manual transmission vehicles (except where fitted with E.L.B. system), tum the mixture screws anti-clockwise until engine speed just rises to the specified curb idle (850 R.P .M.).
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REV. OCT. '78