How to Index Spark Plugs on Evinrude E-Tec Outboards During Replacement

How to Index Spark Plugs on Evinrude E-Tec Outboards During Replacement

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Properly indexed, the spark plugs for the Evinrude E-Tec outboard motor put the plugs' spark gap where it will fire the fuel and air mixture entering the cylinders, without having the plug "drowned" by the mixture. The process is straightforward. It involves establishing where the gap lies on the plug, where the gap should be when the plug is screwed into its bore in the cylinder head and what to do if everything doesn't quite line up.

Items you will need

  • Marking pen

  • Spark plugs

  • Torque wrench

  • Di-electric grease

Turn the spark plug until the gap between the ground electrode and the anode is facing you. Make a vertical index mark on the plug's white ceramic insulator directly above this gap with a marking pen.

Insert the spark plug into the No. 1 spark plug bore and tighten it with the 5/8-inch spark plug wrench and note the orientation of the index mark on the ceramic insulator. Think of the cylinder bank as the face of a clock. On the starboard cylinder bank, the spark plug's index mark must rest between 12 o'clock and 3 o'clock. On the port cylinder bank, the index mark must rest between 9 o'clock and 12 o'clock. Tighten the spark plug to 15 pound-feet of torque with a torque wrench.

Switch the torque wrench to 30 pound-feet if the plug is close, but not quite indexed properly, and try to move the plug so the index mark is in the correct location. If the index mark is still in the wrong location, move the plug to the opposite cylinder bank.

Apply di-electric grease around the tip on the ceramic of the plug. Install the plug wire.

Repeat for all cylinders.


  • Disconnect the negative cable of your battery before performing any maintenance work on your outboard motor to prevent electrical shock or accidental starting. Remove the nut from the negative post with a 5/16-inch box-end wrench. Lift the cable from your battery, move it outside of the battery box and close the lid of the battery box. After the work is complete, reconnect the negative battery cable.


  • The No. 1 cylinder is always the uppermost cylinder on the starboard side. No. 3 is below No. 1. On the port side, the uppermost cylinder is No. 2, followed by Nos. 4 and 6.
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