I recommend the NGK R6725-11.5 spark plug for 100% duty cycle
operation. Gapped at .010" to .012".
Race car settings. There you
go...............rotary talk.
Lynn E. Hanover
This is what I would do.
Get all of your tuning done on the ground and or, just above a long runway.
Install a heated oxygen sensor,
Plug heat ranges in the 10s are for heavy street use. Not used (or should
not be used, my opinion) for a 100% duty cycle as in aircraft.
If 10s cured your problem you have already demonstrated to yourself
the problems of a too hot a (high heat range) plug. Once the tip of the plug is
overheated you have lost control of your ignition timing. This is a very bad
idea. Followed by preignition and or, detonation.
Both can lead to severe engine damage. Once your testing is
complete and long flights are next, I would remove and discard the stationary
gears and magnaflux the rotor gears. You can check all of the engine parts
at that time.
The NGK R6725-11.5 plug is gifted to most competitive race teams by Mazda.
Know what your timing actually is. Mark your flywheel teeth with colored
paint. Easy to see and very accurate.
Lynn E. Hanover