M magneto trouble

When I thought the magneto needed a new coil (as I mentioned in a message I sent a while ago), I took the magneto apart. I bought a point file and filed the points, and, after that, I got it to spark, so apparently the problem I thought was with the coil was actually a problem with the points. When I first put the magneto back together and back on the tractor, it seemed to be working properly. I removed the #1 spark plug and put it on top of the oil filter. I then turned the power-takeoff, using the front section of a PTO shaft from a Fox chopper for a hand crank. When I did that, the spark plug sparked every fourth time the magneto clicked, as it should. However, I tried the same thing a while later and then the spark plug sparked sometimes, but not every time it should. Now, I can't get the spark plug to spark at all unless I connect it directly to the coil, where the coil wire belongs. Then, it sparks every time the magneto clicks. Since the spark plug sparks when connected directly to the coil but not when connected to the distributor cap, I think the problem must be with the cap or rotor. Do you have any idea what to do about this problem?

What type of wires are you using? Are they copper core? Also, what type of rotor do you have? Is it the newer style, with a set contact, or the older style, with an adjustable contact?

If you wires are not copper core, replace them. Mag's don't like resistor wires.

The contact on the rotor does not appear to be adjustable. I don't think the wires are resistor wires. Whatever kind of wires they are, the coil wire and three of the spark plug wires are from a 1970-something Chevy pickup truck, and I think the fourth spark plug wire might be one of the tractor's original spark plug wires -- at least, it's painted red and was used on the tractor in the 1980s. I got it to run with the coil wire and spark plug wires that are on it now in 2003-2006.

If you have good spark like you say when coming direct off coil, your problem is in either cap, rotor, wires or internal timing of the rotor. The reduction gear has an R and L and the R should be lined up with the notched tooth on drive gear. Make sure point gap is .013 as more or less will effect lag timing.

Maybe you need new wires???

(quoted from post at 14:58:11 08/11/10) The contact on the rotor does not appear to be adjustable. I don't think the wires are resistor wires. Whatever kind of wires they are, the coil wire and three of the spark plug wires are from a 1970-something Chevy pickup truck, and I think the fourth spark plug wire might be one of the tractor's original spark plug wires -- at least, it's painted red and was used on the tractor in the 1980s. I got it to run with the coil wire and spark plug wires that are on it now in 2003-2006.

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A 1970 something chevy truck definitely used resistor type spark plug wires.

Bill, with all due respect, invest in some new, copper core plug wires and also one for the coil.

the wires are shot, IMHO.

Apparently, the problem was that the contact on the rotor was somehow too far away from the contacts on the cap. I pulled the rotor a little bit away from the rest of the magneto and then put the cap back on. I then got the #1 spark plug (connected to the distributor cap) to spark once. After that, I took the rotor off and put some pieces of burdock leaf in between the rotor and the shaft that turns it (but with the rotor still far enough onto the shaft that it can't turn without the shaft turning) and the magneto seemed to work properly after that.

Sounds like the spark is weak to begin with. It should jump 1/4 inch out of the coil & that will be enough to jump the rotor gap to the cap.

Do you mean center contact or individual cyl contact points. Center is of course spring loaded brush so directly in contact with rotor. Others may be worn, cap not fitting properly, wrong cap, or timing of rotor like I pointed out before. I have an old cap I keep around that is cut in half so I can observe where the contacts line up as some times you run into drive gears that are not marked or other problems.

30+ year old spark plug wires..................................?

burdock leaves?

Are you truly looking for sound advice or are you trying to get people going here?

Most likely the trouble is still bad wires.

I did that mostly just to see if I could get it to spark that way, and it did spark. I thought probably the best thing to do would be to replace the rotor and cap, and possibly also the spark plug wires, but the closest Case IH dealer is far enough away it takes about an hour to get there, and I haven't had an opportunity to go there since I discovered that problem with the magneto. Do you think the problem was actually that the spark is too weak because of the wires and it would work better with new wires?

absolutely. you do NOT have to go to a CIH dealer to get wires, rotor, and cap.

Tractor supply has them, and so does NAPA (or at least can order them in)

My honest opinion is get copper core wires first. Clean up the contacts on the rotor and inside the dist cap. Don't throw good money after bad. If the wires are as you said they are, then they absolutely need to be replaced, and replaced with copper core wires. Heck, you can buy the parts at NAPA, and make your own wires. That's what I do. I bought a 50' roll of copper plug wire. Box of boots, and a box of connectors.

If you don't want to make your own, TSC (tractor supply co.) has sets pre-made.