Farmall C magneto

I pulled my 48 C out of the shed yesterday where it had been sitting for about 8 years. I can not get any spark from the magneto coil lead. Impulse seems to be working and the points are clean with .013" gap. Any ideas where to look for a solution?

Thanks.

Possible kill wire or switch is shorted, unhook wire at mag to check, try wiping the points with a dollar bill as they may be oxidized or have an oil film on them. Just a couple of things to try, hope this helps.

Tried disconnecting the kill wire. I will double check the points. Dollar bill may be a problem as I am in Canada and we use a dollar coin.

The flap off the box point etc. come in works just as well as a U.S. dollar maybe even better

And a nice clean piece of white "cardstock" works even better.

Never did figure out why anyone would want to drag a dirty, human skin oily, ink-coated piece of currency thru breaker points, and your "box tab" probably has printing/ink on one side of it.

I fold it in half so no ink get to the point surface. Found if you look after running the flap threw the point if it comes up wit ha gray coating the point did in fact need some TLC

Kraft paper works pretty well. When paper grocery sacks were common, they were a good source. I hunk peeled off one side of a cardboard box flap is usually pretty clean and works OK.

The only advantage I see to the dollar bill is that it may be the best thing available when out somewhere and a tractor quits.

If your like me the wallet stay in the house when I am messing with a tractor at my place. Ya if I am on a out call I have my wallet but will still use a business card or box flap before a dollar bill is even thought of being used

Tried the cardboard with no joy. However when I put a meter between the open point and ground I get no resistance. All looks nice and clean. There is a wire coming from the spring anchor disappearing inside. Is there a condenser maybe shorted and how do I get to it? Never have had one of these apart before. On a previous post on H4 mags there is a illustration of the timing marks. I can find the marks but how does one separate the gear from the cover to ensure alignment when reassembling?. It comes a little ways and gets tight. Do not want to damage the rotor mount by forcing it. Thanks

With the point open you should get infinite resistance with the points closed you should get zero resistance. Yes there is a condenser but do not remember of hand how to get to it. I was going to look at a mag I had laying here but it seems the have gone AWOL on me

When you measure from the open insulated point to ground, the coil's primary winding is shunted across the open points and has likely less than an Ohm of resistance, even when good.

Low Ohms values are tough to read accurately without literally a "lab grade" meter, so the "no resistance" reading you are getting MAY be simply the normal low resistance of the primary winding. Or it could be indicating a shorted coil, a shorted condenser, an odd short in the points themselves, the primary wiring from the points to the condenser to the coil could be somehow shorted, could even be a short at the insulated bushing where the condenser and the wires from the coil and points all join together.

Remove the bakelite cover over the coil and you can see the condenser and the wires to it from "above".

As to the timing of the rotor gears, if the marks are aligned, install the little 2-screw cover over the gears, you're done there, and when you install the assembly onto the magneto body, there's a flat on the shaft that mates with a "D" opening in the gear and it can only go together one way.

At this point, once the coil cover is off, I would remove the hollow brass hex screw where the "kill wire" attaches , freeing the condenser from the mag, and the two wires going to it.

Then, check the condenser, the open points, and the coil for resistance separately, and also, then with the points "closed" check that the "open" you should have been seeing across the points now has changed to indicate continuity through the closed points to ground. In other words, that the points are actually making contact and don't still have an insulating oxide coating, or even paper lint and debris between them.

Post back and let us know what you find!

I bit the bullet, set it to TDC and pulled the mag off. Removed the condenser and coil primary. The coil primary shows 0 resistance to ground. With that unhooked all other resistances seem fine with 0 with points closed and infinity open. Same with the condenser back in but not the coil primary wire. Does this mean that the coil is bad? Seems funny as it was OK when I drove the tractor into the shed years ago.

There's your key years ago. Coil can go bad over time just from sitting do to heat and cooling and overtime thing break down and insulation can go bad etc.

Gotta use a 5, that makes Canadians high rollers.