jm, if a coil is labeled "NO EXTERNAL RESISTOR REQUIRED", that means it works on full 12 volts.
When I said "it it drops to 8-9 volts it has a resistor." I mean the vehicle wiring is equipped with a resistor.
Coils can be a confusing issue, lots of different values, and it's done with the internal windings. There was one exception, a Chrysler product I believe, made a coil with an internal resistor for a short time many years ago, not much chance any of us will ever deal with one.
For simplicity, we'll stick with the typical point type, standard performance, stock factory ignition system used from the 20's through the early 70's.
For your Scout, first you need to determine IF it has a resistor in the primary coil feed from the ignition switch.
There were 2 ways that was done. Either there is a visible white ceramic resistor, sometimes on the firewall, sometimes on the engine near the coil. Or some used a resistor wire hidden inside the wiring harness between the ignition switch and the coil.
To determine IF it has a resistor, ground the - terminal of the coil, have your volt meter ready, turn on the ignition and check the voltage at the + terminal of the coil. If there is a reading around 8 volts, there IS a resistor present on the vehicle wiring.
If the reading stays up near battery voltage, there IS NO resistor on the vehicle.
Run your test quickly and turn the ignition back off. Leaving it on will overheat the coil, even possibly burst it!
Now that you know if it has a resistor, or does not have a resistor, you can select the proper coil.
A NAPA IC14SB is a standard 12 volt, 3 ohm, no resistor needed coil. If your Scout has no resistor, this one will work.
A NAPA IC7SB is a standard 6 volt, 1 1/2 ohm coil. If your Scout has a resistor, this is the one you need.
The NAPA numbers are just a convenience, not promoting them, just an example. But whatever you buy, if you do buy one, be sure to open the box and check the part number printed on the coil itself, don't go by the box or what the counter tech hands you. Coils are dinosaurs, they commonly get shuffled from store to store, reboxed, restocked, recataloged. Just be sure you get what you ask for.
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Today's Featured Article - Tuning-Up Your Tractor: Plugs & Compression Testing - by Curtis Von Fange. The engine seems to run rough. In the exhaust you can hear an occasion 'poofing' sound like somethings not firing on all cylinders. Under loaded conditions the tractor seems to lack power and it belches black smoke out of the exhaust. For some reason it just doesn't want to start up without cranking and cranking the starter. All these conditions can be signals that your unit is in need of a tune up. Ok, so what is involved in a tune up? You say, swap plugs and file the points....now tha
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