I have been reading the ignition information with some interest.
The Plasma system didn't surprise me any with melting/burning off
the tip, the insulator, etc.

When the Toyota Tercel first came out (1979?), about half-way
through that first the model year they had to change to use a
dual gap plug. If one didn't use a dual gap plug, it would burn
the adjustable electrode off (the one that is bent to allow an
adjustable gap for "gapping" a plug for those who wondered what I
was getting at).

I believe it was Mazda had a 4 gap plug back in those days (we
are talking 1979-83 or so).

Given that the intake flow is at such a volume and velocity that
we are seriously dealing with fluid dynamics, would having a
"high energy" ignition with a dual gap plug work? And as I think
about this, I think I understand why Mazda used a 4 gap plug --
because one can't guarantee that the gaps would be placed
correctly given the threads and torquing of the plug for sealing.
So a 4 gap plug would possibly do better for that situation.

Years earlier, Kawasaki used a plug with a center electrode and a
concave metal plate that would allow the spark to jump around
from point to point on the face. This was used in two-cycle
185cc(?) dirt bike as I recall. It didn't like regular plugs
(would burn off the electrode just like my Tercel did).

Just trying to figure out how to get better performance with the
rotary engine, possibly with off the shelf parts.

Regards,
Steve Thompson

We use a single gap in the TTC set to .025 inches. No trouble at all.
5 or 6 flights so far. It is a very cooled racing plug.

Paul Lamar

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