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

 
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.