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Spark plug gap erosion

 Spark plug gap erosion

  • The spark carries with it a portion of the electrode, part of which is deposited on the other electrode.
  • The remainder is blown off in the combustion chamber. As the air gap is enlarged by erosion, the resistance that the spark must overcome in jumping the air gap also increases.
  • This means that the magneto must produce a higher voltage to overcome the higher resistance.
  • With higher voltages in the ignition system, a greater tendency exists for the spark to discharge at some weak insulation point in the ignition system.
  • Since the resistance of an air gap also increases as the pressure in the engine cylinder increases, a double danger exists at takeoff and during sudden acceleration with enlarged airgaps.
  • Insulation breakdown, premature flashover and carbon tracking result in misfiring of the spark plug and go hand in hand with excessive spark plug gap.
  •  Wide gap settings also raise the coming in speed of a magneto and therefore cause hard starting.

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