There is room for two sets on the heat sink.

  It can be cut down to 3.5 inches by six inches.

  Don't forget a 4 stroke piston engine coil fires half as fast as a rotary
  engine coil or a two cycle engine coil. Therefor a four stroke coil can't
  be expected to live running at sustained high RPM on a rotary or two cycle
  engine.

  Paul Lamar

  Don'€™t most 4 stroke engines still fire the plug on the exhaust
  stroke also? That would make them the same wouldn'€™t it?

  Bob Mears


  I don't know what they do for sure. Most are computerized and it does not
  make sense to do that as the coils would suck down twice the current. Most
  EFI systems have a camshaft sensor.

  Back in the old days the distributor ran off the cam shaft and  that was
  geared down 1 to 2 revs of the crank. They fired on the power stroke only.

  Paul Lamar



  I will look into that and let you know. Most of my later years turning a
  wrench I know they fired the plug on the exhaust stroke also to help burn
  any fuel that may still be in the chamber. All for emissions of course.

  Bob Mears

 Bob, the reason for the spark on the exhaust stroke is NOT for
 emissions.  The reason is that the ignition can be simpler and
 cheaper.  The coil is made with the secondary winding not
 grounded.  It is referee to as a "floating" secondary.  In a 4
 cylinder engine #1 and #4 will be on either the compression
 stroke or exhaust stroke.  The system would use 2 coils, one for
 1-4 and one for 2-3.  The exhaust stroke spark is referee to as
 a wasted spark.  The japanese motorcycle industry used this
 system in the late 50's.  The other thing to remember is that in
 this system one plug fires BACKWARD side wire to the center
 electrode.  Is you use a fine-wire electrode plug the backward
 plug will erode it.  I have often wondered if this was one of
 the causes of "sag".

 Bill Jepson

 This is called wasted spark. Ever since the RX8 this has been done away
 with. It is now one coil per plug.

 Paul Lamar

Paul, correct, wasted spark as I mentioned. Newer smaller coils allow
single coil per plug, but not everyone is using a single coil per plug
system. I believe that the coil on plug technology will be best for
rotaries. Time will tell
Bill Jepson.

If you sand the bottom of an RX8 coil you can do away with the islands on the heat sink. Careful not to overheat them. Sand for awhile and let them cool. Use heat sink compound.

I have 2 All Electronics heat sinks cut to 6 inches long for sale. $20 each plus $5 shipping. Minor cosmetic problems easily rectified.

George was right on about waxing the carbide chop saw blade. Do it before any cut and inspect the blade afterwards for galled aluminum. Clean that off before cutting again.

Paul Lamar