Farmall Cub

Which type of ignition is preferred as to being reliable? The magnito that I have needs a rotor ($38 approx) and the coil ignition I have needs a coil and ballast resistor if needed. Is one better than the other and for what reasons? Is there a way to check out a magnito to see if the internal coil is operating correctly?

Thanks,

John

This is a lot like asking which oil Many on here have strong opinions. I say go with the one you are more comfortable with, both are reliable in my opinion. I don't keep the 6 volt batteries up on mine, so I keep magnetos. However, I also know how to rebuild magnetos, no mystery to me. I can hand crank all three of my cubs in any of our SC weather, so no issue about battery not being kept up. I guess for me the mags have a certain charm, because most people don't understand them very well. It's your cub….

on the 3 cubs i have had that had mags i cleaned them all up and got them working, then got a 4th cub that had coil and converted my other one from mag to coil. It was my expiernce that the coil makes a hotter spark and starts better than the old mags ever did for me. i suppose for a lot of money i could have replace the coils in the mags and they would have been hotter but for me it was simple as an old auto coil and a ballast resistor and we were off and running better than ever. for a working tractor that you don't want to mess with i vote 12v and coil. just my 2cents.

Both systems work fine, the down side is parts for a mag can get pricey compared to a distributor, $60 coil cap, $75 coil

John, you can test the magneto coil with an ohmmeter if you have it in hand. I don't remember what the value is, but I've replaced a few over the past 20 years and both had failed "open". If your coil if open, you won't get any reading. Measure between the lead and the button on top of the coil. It's possible to have a shorted turn in the coil which will give a good ohmmeter reading but it won't work but from my experience this is not the normal failure.
If your points are working, the easiest way to check for spark is to pull a wire off a plug and then plug a test spark plug into the dangling wire. Set the plug so that it gets a ground, setting it on the exhaust manifold is a good way to do it. Crank the engine and look for spark.
If you have the magneto on the bench, connect a plug to the high voltage socket and ground the plug to the metal case of the magneto and turn the mag quickly clockwise past the trip point and look for spark.
I have two magneto cubs and like it, there's pros and cons to each ignition system. I just had to replace a rotor and like you say, they cost too much. And the coils are expensive but they normally last a long time. The last one I bought didn't fit under the cover and had to file it down some to fit it. Luckily I didn't file into any wires.

It is a matter of preference. All 3 of my cubs have magnetos because that is what they had and I had no reason to change them. My dad's H which I also own originally had a magneto, but was changed before I owned it, and again I saw no reason to change it back. The big problem I have seen with magnetos is that those high priced coils tend to only last 3 or 4 years.

If you replace your magneto rotor, check the teeth of the pinion gear that drives it. If it's teeth are worn down to points it will wear the rotor out a lot faster than normal. One good thing though, it is pretty rare that those rotors need to be replaced.

You already know my vote,----BATTERY IGNITION !!!! --- hotter faster starts,---AND you can run them on either 6-v direct or 12-v with resistor! LOL!!! your choice! happy hunting!! LOL!! thanks; sonny