Farmall Cub

Sure sounds like the cap or rotor is leaking off your spark. I understand cap is new, but would still check for traces of where the spark might be leaking. I also would look at the rotor very closely, although I don't think I have ever seen one leak the spark to another ground. Be sure the copper is still tight on the rotor, and not able to move off to one side or the other, that would affect the spark quality. I have some good used rotors I could send up for a test if you want, before you spring for one. Just send me the address in a pm, or on the forum, as you wish. Lastly check the coil wire in particular, and the connections in the cap. Maybe the moisture caused some corrosion that is robbing your spark. This one has been a real brain teaser, that's for sure!

Are the plugs new as well? If not, I would suggest trying a new set of plugs.

New plugs also. And gapped correctly.

CHECK AND RECHECK CONDENSOR MIGHT TRY A NEW ONE OR TWO ??????

GOOD LUCK
LOMBARD------SC------

How does one check a condenser?
And please tell me you are kidding about the "or two" otherwise I will be very confused. lol.

I just ordered a condenser anyway. And new points as they looked pretty mashed up. We'll see what happens.

You can use an multi-meter set to resistance - highest scale. Place one lead on the case and one on the lead of the condenser. If the condenser is good the resistance will start low and then increase to an open circuit value. It helps if you have a meter with a needle ...digital meters can be a bit harder to read in this case.
here is a video that may help....


Good luck!
CPIII

Quick update - I'm still where I was before.

New condenser, new points, gapped to .013, and still just intermittent spark at the plugs. I don't see anything weird on the cap to suggest I'm leaking spark (although I don't exactly know what I'm looking for). I did notice on the rotor teeth that there are little pockets from where the pinion gear has been pushing up against it. It still doesn't seem like it could wiggle very far, and looks fine other than that, but I think I'm going to order a new one anyway. And while I'm at it see if I can get some impulse coupler pawls so I can use the hand crank in the future without breaking my hands off.

http://www.magnetoparts.com/ is the only place that looks like it might have pawls (and it's also got the cheapest price on the rotor), however it only lists pawls for the H4. Anyone know if they are the same? I emailed the guy and asked, so I'll see what he comes back with.

My lawn is starting to get long. I hope I can it running soon.

Suggest you try Mainely Magnetos. They do a lot of repairs, are helpful and have Parts for the J4. You will have to ask him about the pawls. Also, post a want in the Wanted Cub Items forum, it is possible a number of our members may have parts mags available that you could acquire.

Wow! this is getting to be a long running thread but great information on ignition systems. While I skimmed the comments, a thought occurred to me. I almost hate to add it to the list but is it possible there could be a valve or two that got hung up with all the rain and moisture you had? Is your exhaust a straight stack or is it out the rear? How long did the tractor sit outside in the rain? If you can pull the plugs without too much effort, it may be worth conducting a compression check on the cylinders.

H4 and J4 pawls (as well as most other parts) are NOT the same.

Success! Finally!

I caved and ordered the $40 rotor - and it made no difference. So as a last resort I put a little wire brush on my Dremel tool and scrubbed all the contacts on the inside of the distributor cap. After that I saw good spark to all the plugs, so I hooked every thing back up and it started right up. I wish I would have tried that before.

I'm a little surprised my < 6 month old distributor cap needed that - but I'm happy. Do you think this is a bad cap, or if I keep it out of the rain will it be fine?

Thanks for the info on the H4 vs J4 mags. I figured that was too easy, but it was worth a shot.

Per the valve thing - I was REALLY hoping that wasn't the issue. LOL. I was in over my head enough with the ignition system, I didn't want to add valves to the list.

Thanks EVERYONE for all the answers, and for being patient with my stupid novice questions.

Are your contacts aluminum or brass. I've seen the aluminum do that before.

Scott:

I have had a cap do that -- I took it back to my dealer - it was off-shore IIRC. Doesn't take much to get oxidization on the contacts especially if the cap doesn't seal well and it is humid out. Thanks for reporting back on what the problem was.

Now, don't forget the valves -- just use some SeaFoam in the Crankcase and in the gas .. 1/2 can per, and that should help. At some point it would be a good idea to check the lash. It isn't difficult...... if I can do it, anyone can -- seriously

ScottJ wrote:......... I wish I would have tried that before..............

Kind of like when you loose something and you always find it in the last place you look for it. I always wish I would of looked there first

Glad you got it running, and learned quite a bit in the process. Now it's time to learn about those valves. Don't let it intimidate you, for goodness sakes, YOU OPENED UP A MAGNETO!

Rick Spivey wrote:Are your contacts aluminum or brass. I've seen the aluminum do that before.

They look brass to me.

Scrivet wrote:Now it's time to learn about those valves. Don't let it intimidate you

Now that it's working, I have already been reading about valves, compression, vacuum, etc... I'm sure I'll be elbow deep in there in no time - and then I will probably come back on here with another stumper. haha! I was mostly just afraid of having to look at the valves because then that would add another list of things to question if it didn't run after. I already have no idea if the cap was the root issue - or if it was something else, but because I had the cap off so often working on it I let too much moisture at it.

Anyway, hopefully this thread helps someone else out in the future. It certainly helped me.