Hi Paul,
Was looking at the the engine in the attached pic, and sorry to digress from
the oil line discussion.  I noticed the plug bosses still in place and was
very interested to find out your preferred plug for aircraft use.  I realize
the engine shown still may be in road trim, being readied for aviation use.
During an engine build I would remove the bosses for the client so they
could use much cheaper plug options, a big saving at tune up time.


As well as standard I have tried many other expensive options and generally
been unhappy with durability.  When I first started racing $25 NGK B8-10
EGV's were the order of the day.  Not sure what they charge for those
nowadays.  For expensive race plugs they never lasted long, even with a
points and condenser style ignition system.  The CD ignition setups I saw
used to chew up plugs.  Especially without resister type leads.

The standard plug, surface discharge type, I found less than durable, and
never saw the point of a plug that couldn't have the gap adjusted.  To be
fair they weren't designed for high boost or race applications.  And that
Surface Discharge configuration fits the Rotary well, pointing its spark
directly towards the combustion chamber.


By the way, I have no financial interests in NGK. Over the years had very
pleasing results with a cheap plug used in earlier Mitsubishi turbo cars.
At around $7, its the B7-8 ES.  The number that denotes the heat range of
the plug will of course be personal choice and governed by engine and usage.
They lived with anything Ive thrown at theme, one set did me two years of
road and race use, I just used to keep them gapped.

Sammy

http://www.rotaryeng.net/Spark-plugs/Spark-plugs.html


Paul Lamar