Farmall M Tractor Won't Start

I own a 1951 Farmall M Tractor that has always started and ran great! I went out to start it the other day and it wouldn't and it seems to have no spark. It has the horizontal IH distributer. I have replaced the ignition points, and condenser, the rotor, the coil and the ignition switch. It still has no spark. Can any of you old IH guys tell me what to check next? I'm not a mechanic but I do like to tinker with my old tractors. Thanks in advance for any advice!

Try a hot wire from the non ground side of the battery to the ignition side of the coil. Ignition side if the side that is not going to the distributor. If it has spark when hot wired you have a bad wir or other such thing

Is it 6 or 12 volts? If its 12 volts and has a resistor in the line then good chance the resistor has gone bad.

Tell us what your method of checking to spark is. First I would suggest checking for spark out of the coil by holding the end of the coil wire pulled out of the distributor cap about an 1/8 to 3/16 inch from a metal engine parts and have someone crank the engine. Actually an ideal spark should jump a 1/4 inch an be a straight blue thin line. If it is a 6 volt and you have used the starter quite a bit the battery is likely low on charge. Hopefully you have a charger to correct this. If it has been converted to a 12v the battery charge is not as critical but still applies. If you find no spark in the check above the only real good way to check your problem is with a test light or volt meter. Any auto parts store will have a fairly economical test light. First check would be power with the switch on to the coil terminal that does not go to the distributor. The second would be checking the opposite terminal on the coil that does connect to the distributor while cranking the engine to see if it flashes on when the points are open and off when they are closed. If it stays on when the points contacts are closed the faces of the contacts are not clean enough or the are set way to wide. Let us go through these steps and see where it takes us.

Edit for minor corrections.

This post was edited by used red MN on 09/10/2022 at 05:09 pm.

As pointed out, a test light is needed. An M Farmall will naturally stop with the points closed. If you replaced the points trying to fix it, did you turn the engine to the high point on the distributor cam, then adjust to .020 inches? New points have a preservative film on them that needs to be taken off for them to work. Finger nail polish remover, or lacquer thinner on a Q-tip works. Then a folded dollar to get the fuzz out. With the battery charged, and the points closed, spark can be generated in the coil wire (position the wire as noted below). With the cap off, turn on the ignition, use a plastic handled screw driver to open the points with the screw driver. A small primary spark should be seen at the points. A larger spark should be from the coil wire If no small spark, you may have accidently grounded the pass through where the small wire goes to the distributor from the coil. If this is the case, the wire connection at the distributor can be taken off that pass through and brushed against the distributor body. if no small spark there, you need the test light to discover where the connection or wire has failed. Starting at the power to the ignition switch from the amp meter, and following the power to the switch then to the coil and from coil to distributor. Let us know what you find. Jim

Isn't the horizontal a Magneto? My 51 H is.

Try also a new disgtributor cap. The center electrode might be worn down too much.

In the world today you are lucky if 1 out of 3 condensors are any good sure wish I learned how to test them from a mechanic friend years ago