The best way to find top dead center is make a hose barb
 fitting out of a spark plug and fill a plastic tube
 and the chamber with ATF. Rock the e-shaft back and fourth
 until the ATF in the tube is at its peak. That is TDC.

 Ford EDIS ignition controllers will work without computer
 input, set for 10 degrees of advance. It just needs a
 power source and input from a vr sensor. In normal
 operation, the computer sends a correction signal
 that the controller uses to change the spark advance.
 One EDIS would be set to control the leading plugs
 with a wasted spark, and the second would control the trailing.
 The EDIS system requires a 36-1 wheel (36 teeth with 1 missing).

 You can test the vr sensor and timing wheel by chucking
 the wheel in a drill press and jigging the sensor next
 to it. Attach an o-scope to the sensor output. You'll
 also be able to tell what the tolerances are on the
 spacing between the vr and the wheel.

 Make folders and drag these messages into the folders.

 Paul Lamar



 Karibian.

 Systems with a toothed trigger wheel have one tooth omitted in
 order to reset the internal counter once per revolution. After the missing
 tooth passes  it counts to a predetermined number of teeth and fires a
 plug,
 then continues counting the same number of teeth to fire the next plug
 until
 the reset tooth passes and starts another revolution. If it is connected
to
 the  EEC IV computer,  engine mounted sensors determine fuel injection
 pulse
 width and optimum ignition timing. The computer sends a SAW (spark angle
 width) which decreases the number of teeth  as well as the fractional part
 of a tooth counted for the first plug after the reset tooth. The rest of
 the
 plugs fire  at the tooth count after the first plug firing point. To run a
 fixed timing the computer adds no functionality since the EDIS runs at 10
 degrees advance without the computer.

 The actual fixed advance is determined
 by the mounting position of the VR sensor (teeth behind the missing
tooth).
 IMHO firing both plugs on a rotor using the wasted spark side of the coil
 would be a mistake. The EDIS accumulates a fixed charge which is
discharged
 through the coil. You might think of this as the condensor on a points
type
 ignition. The intent is to fire one plug of a cylinder under compression
 and
 one which is not. Firing two plugs both under compression requires more
 voltage and might misfire at high RPM or result in overheating the coils
 without cooling air directed over the coils.

      The single  tooth ignition calculates the percent of time  required
 of the time for a complete revolution to determine the spark events. This
 would  consist of several solid state timers and comparitors. A timing map
 is usually incorporated for spark advance.

      It is possible to have a VR sensor for each spark plug with it's own
 coil on plug and no computer chips. This approach  would
 have  fixed timing
 and relies on a precision mounting of the VR sensors both in their
relative
 location and spacing from the trigger tooth as it passes. With this
 approach
 a small amount of  electronic components and a capacitor to fire the coil
 is
 required  for each plug since the VR sensor doesn't fire the coil
directly.

 george grimes

 Let me see if I can simplify this.
 The attached pdf is very clear on how it works.

 "Inside the EDIS module is a microprocessor, VR sensor input, and coil
 driver transistors. The VR sensor drives an input detector which fires
 on the falling zero crossing of the [CAS trigger missing tooth] signal
 at ­300mv. The module then uses this information to calculate the current
 crank position and speed [RPM]. When the EDIS module determines the
 spark should be ignited, [front rotor back rotor] it fires the
 appropriate coil."


 IMHO If you use only one EDIS system and one pickup
 and one coil pack and the unit is set to 4 cyl
 you will get wasted spark I think. The four cyl setting is used
 because a 2 rotor fires the same number of times per engine
 rev as a 4 cyl piston engine.  As George pointed out wasted
 spark is a no no in a rotary.

 However since each  Ford coil has four spark outputs
 and there are four trigger wires coming out of the EDIS
 that support two coil packs choosing the right
 outputs using two coil packs may not give
 a wasted spark but you still have four plugs
 to fire. It is too much on my little brain to
 figure out if it can be done with just one coil
 pack without wasted spark.

 I think the firing order in a 4 cyl is 1 and 3 fire
 together and 2 and 4 fire together. If 1 and 2 are fired
 together one cyl will have wasted spark using only one
 coil pack.

 I could be wrong so I would set up on the bench
 and see what happens.


 Paul Lamar


Paul The schematic you posted above is for an EDIS-8 for an eight cyliner
engine which has four outputs as shown to fire at 90 degrees of shaft
rotation increments.  The EDIS-4 for the four cylinder will have two
outputs
to the coils and one four tower coilpack. The EDIS-4 fires at 180 degree
increments the same as the rotary.

         A four tower coilpack is actually only two coils. The primary
winding of a coil is connected to the EDIS output and ground. The secondary
(high voltage) winding is a loop through the coil and two spark plugs in
series back to the coil. the engine block between the plugs is part of the
circuit loop.


     The question I have reguards the automotive spark plugs and plug
leads. There must be some reason for the shielded screw on plug leads on
certified engines. Is it for high altitude performance or waterprofing the
air cooled engine with large amounts of cooling air contaning rain water
grounding out the plugs.

george grimes

All of that is obvious by looking at the patent diagrams.

Well maybe you need the 8 cylinder version.
Are you sure the 4 cylinder is not wasted spark?

The AC engine shields are for radio interference reasons.


Paul Lamar




Paul, Yes the four coil pack is wasted spark as are all coil pack systems. A
four cylinder fires  the1 and 4 coil and 180 degrees of rotation later fires
the 3 and 2 coil. This assumes a 1-3-4-2 firing order.   The next rotation
fires the same coils at the same rotation, the difference is which cylinder
of the pair is under compression and which is  finishing the exhaust stroke.

       You are correct that my particular application will be with EIDS-8
parts because it is an even fire four rotor firing every 90 degrees. If I
connect the two E- shafts in the same rotation  with 2 rotors (one on each
section) firing simultaneously then the EDIS-4 would  have the required
waste spark plug for the second tower position of the coil. A second EDIS-4
would fire the trailing plugs so that the timing can be delayed to match up
to the moving combustion chamber of the engine. With my 90 degree firing
order I need a resistor to replace the waste spark plug, or a false plug
just screwed into a piece of barstock to complete the coil circuit.

      The rotary engine does not have a spark event where the plug is not
sitting over a rotor under compression. The piston engine always has an
alternate cylinder which will compress on the next revolution for the waste
spark plug to be screwed into.If we did fire a plug someplace in the
rotation other than 20 degrees BTDC what do we do when it is actually time
to fire that plug with it connected to a different coil. A single coil
might be fired off the EDIS output, however I preffer to  have the
electrical perameters that Ford designed the ignition for.  They have used
this system in factory backed race cars apparently without component
failures at higher RPM than we will need. The module is only a couple of
ounces and the coils are well mounted.

      If I had gone with the MSD-6 ignition modules and ACCEL coils, both
excellent components,  I would appear that I need several 3 pound control
boxes and the same number of coils which would weigh more, cost more, and
require programming specific to the application.



george grimes