You obtain a set of points, condenser and coil from an old car built
from 1925 through about 1970 or 80.

Those old steel can ignition coils were filled with oil to cool the
primary coil inside the can.

Oil transfered heat much better than plastic used in recent GM Truck
coils. They were designed to survive with the points closed all the
time in case you left the ignition key on.

A ballast resistor would be a good idea. There is only one bump on
the rotor shaft because a one rotor fires only once per rev.

Pep Boys sells the old style coils for about $20 new.

NO distributor!!!! Not needed. No distributer cap. Not needed. No
ignition rotor. Not needed.

One coil per spark plug.

Use two sets of points if you use two coils. It will run on either
one. Fixed 22 degrees BTDC timing.

Make the points bracket out of Home Depot aluminum bar stock. Make
the points cam out off a short piece steel square rod. Grind off
three of the four corners. Weld it to the steel disk and bolt that
to the front pulley.  The pulley  already has four taped holes. You
can slot the holes in the disk to adjust the timing.

This is a reflection of the extreme simplicity of a Wankel engine.

This is almost as simple as the Wright Brothers ignition. They had a
set of points inside each combustion chamber. When the points opened
they sparked.

Dave, You can show this at Oz-Kosh if you want.

Paul Lamar


Paul, would this system limit RPM ?

Steve  Carlisle

Yes but what that would  depend on the pulse rate capabilities of the
points.

The 4 stroke distributor is running at half crank speed and there are
four lobes on the ignition cam in the distributor.

For a four cylinder 4 stroke rotating at 6000 RPM the pulse rate for
the points would be 12,000 pulses per minute. Half speed times 4.

The same pulse rate for the one rotor gives 12,000 RPM.

In other words if you are using the same points and your four
cylinder four stroke will run at 8000 RPM so the one rotor will run
at double that or 16,000 RPM in theory.

Check my arithmetic and logic.

Paul Lamar


Your arithmetic and logic appear unassailable.  With two separate sets
of points, capacitors, and coils, one for each plug, you would have a
fully redundant duel ignition system.  If you installed four sets of
points in pairs 180 degrees apart, and their associated equipment, you
would have the same redundant duel ignition for a two rotor.  As long as
there is power and the E-shaft keeps turning the sparks will continue.

Eventually the points or capacitor will fail but in my experience with
old contact point style ignition vehicles that doesn't happen very often.

  Mark LaPierre


Paul and Mark, Thanks

Steve Carlisle

That sounds great, My experience with points systems has proven to me to be
simple and reliable. There are always signs of a problem before any of the components
fail.

I have a sachs and a OMC but they are charged cooled.
How can we cool them better than adding water cooling to the end plates and
the housing?

David Mikesell

Not easy. Convert to an oil cooled  rotor.

I had not thought of this idea before but our good experience with the dry sump
system on the TTC engine suggest the way to do it is have a totally independent oil
system with the sole purpose of squirting cooling oil up into the rotor.
You need to figure out a way to get pressurized oil into a hollow E-shaft.
A scavenge pump should be able to recover this and feed it through
an oil cooler. No need to change any of the bearings.

Paul Lamar

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