Hey Jerry MT Pic-1

This is the exact wiring I had before my 12V coil failed.

This is the exact wiring I had when I reinstalled the 6 volt coil with the Napa 2.83 resistor. This setup did not produce spark.

I moved the wire off the right side post (output side)of the ballast resistor and put it on the left side of the ballast resistor (input/ignition on side) thus not using the ballast resistor. I replaced the Napa 1.83 ohm resistor with one of unknown resistance and it starts and runs good. I could not edit this picture showing this change. I hope this is not too confusing, but I don't know how else to explain it. My question is "why didn't the setup in the diagram work?" I took the diagram from this site and have seen it reccommended often. I checked for voltage at all points and had satisfactory voltage but no spark.

I don't know what you've got "going on"!

Using NO resistors will make the hottest spark, but soon overheat the coil.

Using TOO MUCH resistance will make the spark too weak to fire the plugs under compression, but there will still be at least SOME spark.

Using the correct resistance for the coil will make a HOT spark, to fire the engine, but not allow excess primary current that will overheat the coil, and damage the points.

It seems to me you have another "issue"... bad switch, or a loose connection somewhere that has made the spark come and go as you have swapped things around.

A Kettering ignition system is not like a solid-state device that has a specific "threshhold" at which it either works, or "cuts off".

You should have AT LEAST a weak spark, even if too much resistance is used in the primary circuit.

Thanks.

Bob

bigcoulee@hotmail.com