no spark at points when turning over

[Hawkeye3828]

Hey guys, I have rewired my Ford 4400 1965-68 3 cyl. as the previous was a big mess. Thought I had everything back the way it was supposed to be, and I looked at some 6v to 12v conversion(which is what I did), but I discovered that I am not getting any spark. I took the dist. cover off so I could see the points and while cranking I do not get any spark across the points but just as the key is turned to the Run position and the motor is still moving I can see a spark happen. This tells me I have made a mistake in wiring somewhere. I have the coil wired so that when the key is in RUN I have 12v to the ignition coil but apparently when the key is turned to START it does not give 12v to the coil. What am I missing? I did a continuity check on the switch when I put it in to check whether the coil wire was getting continuity with the 12v feed to the switch and that was good. This switch has five poles on it. "1" is the 12v feed, "2" and "4" are feeds in the RUN position( "2" is used to drive the electrical temp gauge and "4" is used to provide 12v to the coil) , "3" is the 12v feed to starter solenoid, and "5" is not used. Obviously I need 12v to the coil when cranking but it appears that is not what is happening. Could it be that something is sucking the juice out of the "4" feed to the coil when cranking? What do I have wired wrong? Appreciate your help with this. Thank.

 

[Hawkeye3828]

OK, guys, solved the problem. When the starter switch was turned to "start" it was not giving power to the ignition coil. Solved that by putting a jumper between the "5" and "4" terminals on the switch so that when the switch was turned to "start" the coil would have power. OK so far BUT the switch which is brand new DOESN'T make contact between "1" and "5" unless you turn it ALL the way. If you turned the switch just enough to get the starter to turn it wasn't farrrrrrrr. enough to make the correct connection. I learned all this by watching for spark at the points and at the number one spark plug. Now if I turn the switch ALL the way my tractor runs!! This has been six months of every week doing a day or two of work on it. Looks like the new single wire alternator is charging too.

 

[jimmysisson]

Does that use a 6 v. coil with a resistor? Or a 12 v. coil? The coil should get 12 v. when in the Start position and usually a reduced 6-8 v. in the Run position.
Jim

 

[Hawkeye3828]

Hey Jimmy, I replaced the 6v coil and resistor wire with just a 12v round can coil. So it is getting 12v to coil when running. Curious as to why you would only want a reduced 6-8v when running. Can you explain? Also, wouldn't that require two wires going to the coil?

 

[BukitCase]

A lot of older, standard point type ignitions used to have a "ballast" resistor that was in series with the primary (lo volt side) of the coil - when in "start" position, that resistor was bypassed by the switch so the extra drain during cranking didn't rob too much from the coil to allow good spark.

Once the engine started (you released the switch back to "run") the ballast resistor was re-inserted in the primary circuit to keep the coil from getting too hot.

This also helped point life (by reducing current), as does the CORRECT value of "condenser"/capacitor. Too much or too little capacitance in the circuit will cause the points to pit to one side or the other - just right and they pit LESS, so last longer... Steve