Boy, thanks, Bill

 

Never would have even occurred to me to watch out for mushrooming fine wire electrodes – the knowledge and experience on this list is fabulous!!

 

Ed

 

 

Mark,
One thing to watch out for on the fine-wire plugs, is NOT to run dual lead coils. Some of the systems for the 20B fire both plugs at the same time. This isn't a problem, but some of the engine management systems use 3 coils with dual high-tension leads to make things simpler. Since most of the dual-lead coils use a floating secondary one plug fires normally and the other fires BACKWARD sidewire to center electrode. The plug that fires backward will wear the center electrode out faster. That isn't a problem with standard plugs, but on the high end platinum or iridium plugs the center electrode will erode or mushroom on the end. We saw this all the time on 4 cylinder motorcycle engines where they always used 2 dual lead coils to make the system cost less. The newer high performance bikes have gone to coil on plug designs, and switch the low tension side to eleiminate the problem.
Bill Jepson 


-----Original Message-----
From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Tue, Jul 7, 2009 7:25 am
Subject: [FlyRotary] Re: SAG - NKG