Spark Plug: Description and Operation

This engine uses resistor spark plugs. They have resistance values of 6,000 to 20,000 ohms when checked with at least a 1000 volt tester.

Remove the spark plugs and examine them for burned electrodes and fouled, cracked or broken porcelain insulators. Keep plugs arranged in the order in which they were removed from the engine. An isolated plug displaying an abnormal condition indicates that a problem exists in the corresponding cylinder.

Fig. 12 Setting Spark Plug Electrode Gap - Typical:

Spark plugs that have low mileage may be cleaned and reused if not otherwise defective. Adjust the gap between the electrodes to the dimensions specified in the chart at the end of this section.

Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap. Tighten spark plugs to 27 Nm (20 ft. lbs.) torque.