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Date: Tue, 25 Jan 2005 13:13:55 -0500
From: WRJJRS@aol.com
To: flyrotary@lancaironline.net ("Rotary motors in aircraft")
Subject: Re: [FlyRotary] Re: FW: Re: Plugs and Mags
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Ed,
Do you know what type of plugs Tracy uses, el-cheapo or platinum?  You
said that he runs mo-gas so I assume he doesn't have the lead-fouling
problem you and others have.  So, I assume Tracy's plugs are actually
worn out after 100 hours?  If that's the case, it seems that the
platinum, or iridium plugs might give longer life.

Mark S.

Mark, A comment bearing on all the "fine wire" plugs. If you use coils with dual leads,(two wires out), don't use them. Tracy is now suggesting the LS1 coils which are single output coils. Several of the same-time-fire systems use the dual lead coils. The problem is that one plug fires BACKWARD arcing from the side wire to the center electrode. The center electrode wasn't intended to be the receiving end of the arc.
 When I worked for Kawasaki on bikes they found the platinum plugs started out great but failed SOONER due to the center electrode being eroded and mushroomed. Lead effects can't do anything but make this worse. Motorcycles have used the wasted spark on exhaust stroke forever to prevent the need for a high-tension distributor. The secondary of the coil "floats". It isn't grounded. Both plugs are needed to complete the circuit.
Bill Jepson