It could be a case where the lead accelerates the corrosion of the copper, while leaving deposits that degrade the
ignition system.  Pilots that feel they have enough glider time in nominally powered aircraft always seem to choose to
change out the plugs, rather than fully exploring the extent of what is going on.  Only the very edge of the onset of
this problem has been explored.

If the lead is helping to destroy the copper center electrode while at the same time conspiring to put a wet blanket on
the spark, would a high power ignition simply allow the plug to work until the center electrode is completely corroded
and burned away?  IOW, would a low power ignition actually make more sense in this case, as it would allow for a gradual
onset of the problem and enable the pilot to fly an RV with the performance of a Cessna trainer until the plugs could be
changed out.

 

As I have proffered in the past, with the high performance system you might never suffer the SAG, but if you choose to fly for a large number of hours until the center electrode is gone, once the high powered ignition quits jumping that gap, the show is over for that plug. It is not going to fire again, maybe not even if the throttle is reduced.

 

This would require a shamefull lack of attention to maintenance. And if that be the case, probably spark plugs will not be your biggest problem.

 

I used to look at plugs after every session, or 20 minutes of operation with the Fiat at 14:1 compression. (Champion N-57G). To be sure we were rich enough. I have had the center electrode shoot straight up out of the plug taking off the plug wire. And that was on 110 avgas.

 

With the rotary just twice per weekend to be sure the gap had not wondered off that magic .010" Never power up one of these ignition systems with a plug wire off of a plug. They can commit suicide if you do that.

 

Lynn E. Hanover

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