Farmall Cub

Just picked up this 1950 Farmall M at auction yesterday. It has a few issues but, is worth fixing up in my opinion. It has been converted to 12 volt and has an alternator. Id like to convert this to electronic ignition as I have on some of my other Farmalls. This would be my first one with a 12 volt system though and the tractor has a resistor wired up to the coil. When I replace the coil do I need to reuse the resistor and what coil do I look for? So far the repair list is: front tire needs a tube, rear tires are loaded and I'd like to eliminate calcium chloride, carb is clogged up and needs rebuilt, ignition system rebuild, oil pressure gauge and valve cover are leaking, radiator cap is broken, seat needs rebuilt, also the belt pulley is leaking pretty bad. Im sure Ill find more things to fix but, that's half the fun.

You can use a 12v coil with internal resistor and eliminate the existing external resistor at the coil.

If the existing coil is okay, I wouldn’t replace it. Stock coils work quite well with Pertronix. If you decide to do that, be sure to connect the hot lead, to the Pertronix, to the switch side of the resister, not the coil. Your list of repairs matches, almost exactly, to the repairs I made to the neighbors Super M, everything but the belt pulley seal. Adjust the valves, while the cover is off.

Ok, so I got the hood off today and a 25 ohm ballast is mounted on the alternator. I saw this yesterday but, wasn't sure what I was looking at with the hood on. Also it appears the tension of the belt is holding the alternator tight against the valve cover....? So if I use a pertronix flame-thrower coil I can remove this ballast? The coil on the tractor is leaking and mounted with zip ties and strapping so I want to replace it. Also Im going to have to rework the alternator bracket.

Picture makes it look like that resistor is in the exciter circuit of the alternator rather than the primary feed to the coil. If it is part of the charging circuit, you will still need it.

By the way, an ignition resistor should be around 2 ohms. An exciter resistor should be around 10. I suppose 25 might work okay in the exciter circuit.

As Jim said, that resister is for the alternator, not the ignition system. There’s no knowing what your coil is, without testing it. Approx. 1.5 ohm = 6 volt or 12 volt external resister, approx. 3 ohm = 12 volt internal resister. The instructions for the Pertronix gives the ohm requirements and diagrams for hookup either with or without the resister. Be aware that the Flamethrower coil may not meet their ohm requirement for a 4 cyl. Engine, it’s made for 8 cyl. Engines where lower coil ohms are more tolerable. (An issue of dwell time). It has long been my preference to avoid getting too aggressive with the “hot” coils. The Pertronix will make a big difference, even with a stock coil, it just has to be a good one.

I think I have it figured out now but, I have not tried to start it because the carb is off. I did have to make a bracket to mount the coil though. I hooked up the wire from the alternator going to the + side of the coil same as it was before.

So I got it running after rebuilding the carburetor and it is charging. It does start nicely but, I do have to make some adjustments to get it to run better. I drove it around for awhile and everything seems to work as far as clutch, brakes, and it goes in all gears. It did not like 5th gear and the front end seems to shimmy pretty bad. After parking it I drained the oil. There was a fair amount of water in the bottom of the pan. I took off the oil pan and valve cover and both were coated with white sludge. The coolant is pretty full so I think it is condensation? With the oil pan off the inside of the engine is pretty clean.

Well I'm pretty much finished with the repairs on the M. I have changed axle seals, brake seals, belt pulley seals, rebuilt steering shaft, rebuilt carb and fuel system, built a front hitch, added headlights, and many more things. I had it out today for a 5 mile trip and it did well. I would like to add fenders, a belt pulley, and wheel weights. Also the swinging drawbar is a cobbled together piece off an H so it should be replaced. I'm looking forward to an up coming auction where the owner has trailer loads of farmall parts including 20 sets of weights.

Must be a nice feeling looking at it now and knowing what it took to get to this point. I think the M is the best looking Farmall.

I like the styling of the M too. I can't wait to park it next to my H.

Sounds like it has come along quite nicely. Enjoy!

Looks great and you sound like you know what you are doing. I agree on the fenders...I put a set on my SC to have a handhold while climbing up and for safety...those seats don't always fit my south side. Also as a bonus...consider putting some plate between the current floor pan and the fender to make your floor pan wider. It makes it easier to add a step on the back and to put some nonskid on the whole floor

Got the M to its new home, complete with fenders and belt pulley. Hopefully I can get a set of weights this weekend.

Here's a picture of the M, out for it's mid winter ride. I've since added rear wheel weights, a toolbox, and a mirror which is quite handy.