Decisions to make about the '50 Cub

[Don McCombs]

I need to figure out why it is missing and has no power at high speeds.

Have the valves been checked/adjusted recently?

[Ben B]

Yes, I adjusted the valves this past spring. They needed it too! It might not hurt to check them again though. Now that I know how to do it, it wouldn't take near as long as it did the first time I did it.

I might could check the compression to see if it changed from the last adjustment also, before I go tearing into it. They were so far out of adjustment last spring that it gained about 20 psi per cylinder after I adjusted them.

Its possible they may need it again.

[Ben B]

Another thing I want to address is this magneto. It has been converted to an external coil, and as you can see in this photo there's no coil in it. I plan to rebuild this thing over the winter, at least I hope to.

I opened it up, readjusted the point gap, and cleaned them with contact cleaner. I thought it would have helped with the missing, but it didn't help all that much. I believe I may just need to replace everything. The condenser tested good, but when I go to rebuild it I may just replace everything while I'm at it.

[bythepond88]

Just curious - if a magneto is converted to battery ignition, should the point gap be opened up to .020?

[Ben B]

Well, you pose a good question that I do not know the answer to. It was gapped at .035 when I first checked it, and that was way too big I figured. So, since it is using an external coil, I went for .020.

Another thing though, the timing is not advancing at high speeds either, and I don't understand why not. I am wondering if this kind of set up can even work. That is why I want to repair the magneto.

But, I think it is missing a rod of some type. A few years ago when I mentioned rebuilding it I had some folks tell me what I needed, but I have since forgotten. If anyone could tell me what I need to complete the magneto, I would appreciate it!

[Eugene]

Magneto .013" point gap with or without external coil.

The magneto's impulse coupling drops out at around 250 rpms, Once the tractor starts it will be at full advance, around 13 degrees. After the engine starts that's it, there will be no more advance, which you would see with a normal battery powered ignition system.

[Don McCombs]

But, I think it is missing a rod of some type. A few years ago when I mentioned rebuilding it I had some folks tell me what I needed, but I have since forgotten. If anyone could tell me what I need to complete the magneto, I would appreciate it!

What you appear to be missing, in addition to the coil itself, is the coil core bar. It goes through the center of the coil. They are relatively hard to find separately.

[Ben B]

Thanks for the information fellers. I'll set my point gap to .013 and that may just fix my problem. And I may have to find another magneto if I want to fix mine, since that part is hard to find by itself.

[Don McCombs]

Try placing a wanted ad here. Someone may have one that they're willing to give up. You could also try JP Tractor Salvage at the bottom of this page.

[bob in CT]

Oh, sorry I forgot to mention, but mine is not a demo. It missed the white paint by a few weeks as far as I can tell. Most of the casting codes on it are 4 4 T.

Sounds very close to mine.

[Puffie40]

Should that magneto have oil residue in it? Something seems wrong.

[Bigdog]

Should that magneto have oil residue in it? Something seems wrong.

No - the oil should not be there. Time for a new seal.

[Ben B]

Thank you all so much for the advice! It sounds like its time to do a complete overhaul of the magneto. Nearly every seal on this tractor is leaking, so that makes me think they are all probably original.

You know, I just keep "slapping bandaids" so to speak on this old Cub, but it deserves better than that. I want to fix it right. But, I also have to keep it working because that is its primary purpose. I can't afford a rebuilt magneto at the prices I've seen, but I see no reason I can't rebuild my own if I can get all the parts I need.

I think its time to dismantle the magneto and see what all might or might not be wrong with it. Is there anything I need to watch for when taking it apart?

Thanks in advance!

[Puffie40]

Be very careful removing the rotor - improper handling can damage the rotor's magnetic charge and weaken the spark. Recharging the magnet is possible (plans for a charger are available) but finding that service is tricky to find nowadays.

There should be a procedure in the J4 manual on removing the rotor.

[Ironlegs]

I bought a 1958 Cub about four or five years ago as a second mowing tractor...I didn't need a second tractor but this machine provided me with a restoration project I could do with my young son and, later, a training opportunity with my son when we use it for mowing and chores around our property. Like your machine, it was worn and needed many improvements to be reliable and functional. I put about $2500 into the improvements and, now, declare it dependable. Each year, I spend about $250 for fluids (fuel, oil, coolant, gear oil, grease, etc), ignition parts and filters and for small items like hitch balls, pins, bolts, etc.

I took this on mostly for the shared experience with my son...there's no way it would be economically positive as the Cub is limited in power and function (trailer pulling, skidding firewood, attachments, etc). We're getting mostly mowing service from the Cub and my son is learning many things while he's learning to operate it.

Other absolute needs for restorers is to have a safe and functional space to disassemble the Cub and to make the repairs and to have an adequate set of tools for same. Afterward, a dry and sheltered space it needed to store the Cub is necessary to get lengthy service from the machine without ongoing repairs from weathering.

I do not expect to recover the costs of improvements nor yearly running costs ever. Parts for Cubs are fairly available but many sources offer sub-standard quality parts and charge quite a bit for them. Finding useable attachments can be difficult too. The Farmall Forum provides truly great information on the Cub...second to no other source.

In my view having and maintaining a Cub has to have a sort of sentimental value that overshadows the time, expense and attention it requires to get work from. Your property has to provide a need for the Cub or you have to have an interest in parading and/or showing it or your support for it will wane.