Spark plug check (6000 Mile (10 000 Km) / 6 Month Service)
1 Pull the HT lead from each plug by grasping the end connector. Clean around each spark plug.
Clean around each spark plug ...
Remove each plug
...before using a socket to remove the spark plugs
and check its electrode gap, which should be within the limits stated in Specifications.
2 To adjust the gap, bend the outer electrode with a proper spark plug gapping tool. Recheck the gap using feeler blades or wire gauges.
Measuring a spark plug electrode gap with a feeler blade
Measuring a spark plug electrode gap with a wire gauge
Adjusting a spark plug electrode gap with a special tool
3 Note that the correct functioning of each plug is vital for the correct running and efficiency of the engine. It is essential that the plugs fitted are appropriate for the engine and the suitable type is specified at the beginning of this Chapter. Spark plug cleaning is rarely necessary and should not be attempted unless specialised equipment is available as damage can easily be caused to the firing ends.
4 The appearance of a removed spark plug can give some indication of the condition or state of tune of the engine, but as modern engines run on a weaker fuel/air mixture in order to conform to current emission control regulations, a rather whiter appearance of the spark plug electrode area must be expected than was the case on older cars. As the mixture control is preset during production, a black appearance of the plug electrode will normally be due to oil passing worn piston rings or valve stem oil seals, unless the carburettor has been tampered with.
5 When installing the plugs use a long reach socket, apply a little grease to the threads of the plugs
Lightly grease the spark plug threads before fitting
and tighten them only to the specified torque wrench setting. Overtightening may damage the plug or its seat.