Perry, I did mention this before but if the platinum plugs you are running are on the trailing (leading?) side of a floating secondary coil, ie there are two wires and the coils secondary is not grounded, then one plug fires backward. The plug that fires from the side wire to the center will damage the center electrode. Testing proved this problem existed on motorcycles.

Motorcycles used these coils before cars because it was a way to make a cheaper ignition. The coils
themselves have improved with hotter spark, but still ususlly have a floating secondary. On bikes we
tested to be sure by installing new platinum plugs, running until the performance was affected,
about 30 hours on the crappy bike ignitions.  One of the plug center wires would have a mushroom
shape. Not really pronounced but visible. Replacing that one plug would restore performance.
switching the wires between plugs would "move" the problem to the other plug of the pair. The
temperature of the rotary would probably

make the problem worse. Modern coils would allow the system to run longer without mis-fire, so your 50 hours sounds right in the ballpark. If you don't use this style coil it's probably just the lead.  Bill Jepson

Thanks Bill.  I recently took the plugs out and cleaned them a second
time, now runs good again.

The platinum plugs look like they are in good shape, better than the
standards after 50 hours.

My leading plugs til now have never lasted more than about 50 hours.
 Trailings last much longer.
Could be due to the reasons you mentioned.  The leading plug system uses
one coil for two
plugs and one plug fires "backwards" through the floating secondary
winding. The trailing system is one
coil per plug.

But most if not all of the flying planes use the same system, same as
the car.
Ed seems to be the only one other than myself admitting to short plug life.

I'm certain the fouling is due only to lead, that is the only thing that
changed. Using
the colder plug in the leading position didn't help with the fouling,
but may help plug life.

-Vaughn Mann wrote:

Perry ,
Aren't you using direct drive?  Vaughn.-

Yes.

--
Perry Mick
Duckt N7XR
http://www.ductedfan.com

 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2002 All world wide rights reserved.