My Great Grandfathers 1947 Cub!

[Cubfriend]

Welcome to the forum. Excited for you to get your Great Grandfathers Cub! You have found an awesome resource in farmallcub.com. We are here to help guide you along your journey with the Cub. Try to attend a Cubfest if you can. Cubfests are like going to Cub school. So much can be learned and lots of helping hands. Enjoy the ride along. (It’s the fun kind of school.)

[AHS]

First up welcome to the forum!
Mags are ALWAYS the problem child ! Thats why I trade them for battery dist! Other guys love them and its the matter of personal pref. as to what you have time to mess with. So far I have one cub left with a mag, (dead of course) and need a dist. for this one so I can use the tractor.
You will have to file the points to start with, might get lucky and still have decent coil but it kinda sounds like coil or condenser breaking down when the tractor gets hot.
When it dies check for spark at the plugs first. also get one of the little inline spark testers, (a $5.00 item), these things are a great tool to check for spark even while running, so slap one of them on there and run it til it dies and look for spark when you try to restart it.

Ok, so I’m new to this... mags are ALWAYS the problem child! Can you have a magneto rebuilt? The coil looks to be newer... it’s a factory coil, it has the IH on it! I’m not ruling anything out! Ok, can you have a magneto rebuilt? Can you buy them? How many of you have had them rebuilt? How long does a magneto last? 0-25 y/o? 25 -50 y/o?

[Rick Spivey]

Magnetos can be rebuilt, I must have rebuilt 20-30 by now. But the components can be rather expensive, depending on what is needed. Most people aren't familiar with them or comfortable with them, so many get replaced by battery ignition. I have 3 cubs and an H on magnetos and love them. I don't like keeping batteries up. For quite a few years the tractors were stored 3 hours from where I lived, so when I came to the farm and wanted to use one, I didn't want to mess with a dead battery. I would suggest you file the points with a points file, and reset them. Your cub will likely run enough that you can further diagnose it. Don't buy parts until you know for sure what is needed. As to life, we run on magnetos that were rebuilt in 2007. The worst thing you can do is "snap" it over without a path for the spark, avoid the temptation to do that.

[Waif]

First up welcome to the forum!
Mags are ALWAYS the problem child ! Thats why I trade them for battery dist! Other guys love them and its the matter of personal pref. as to what you have time to mess with. So far I have one cub left with a mag, (dead of course) and need a dist. for this one so I can use the tractor.
You will have to file the points to start with, might get lucky and still have decent coil but it kinda sounds like coil or condenser breaking down when the tractor gets hot.
When it dies check for spark at the plugs first. also get one of the little inline spark testers, (a $5.00 item), these things are a great tool to check for spark even while running, so slap one of them on there and run it til it dies and look for spark when you try to restart it.

Ok, so I’m new to this... mags are ALWAYS the problem child! Can you have a magneto rebuilt? The coil looks to be newer... it’s a factory coil, it has the IH on it! I’m not ruling anything out! Ok, can you have a magneto rebuilt? Can you buy them? How many of you have had them rebuilt? How long does a magneto last? 0-25 y/o? 25 -50 y/o?

My 48 Cub has the original mag far as I can tell.
Beat like a rented mule by prior owners , even had a broken transmission tube...
Mag still fires.
An hour meter with actual hours on it might have had me turn and run away screaming when I looked at it for sale...

[k hutchins]

My original '48 is still running the original mag.

I have replaced components on the front end, condensor, points, coil, rotor, and caps, but it has never needed to be rebuilt internally. I've gone, sometimes years, handcranking it instead of replacing a battery due to laziness or lack of funds, but l could go out right now crank it 1-3 times and it will fire right up.

A new coil would be your most expensive part to replace. Next would be the "geared" rotor. Points, condensor, and cap are relatively inexpensive and where l would start if you're having spark issues.

[AHS]

Transmission fluid is done. I go the compression test done

1 110lbs
2 100 lbs
3 +4 90- 95 lbs

It hasn’t been run since 05.... rings and valves. Should I run seafoam in it? Of course... non ethanol gas! Now onto the carb and points! I’m getting there!!

[Clemsonfor]

I'd say those numbers are fine. Possiblity improve with running if some rings are stuck.

I'd use non E put half a tank of fuel and a whole can of seafoam and work it if possible. If all you have is a trailer put some weight on it and tow it around the place

[Glen]

Hi,
I would open the throttle fully before doing the compression test, so the engine can get air for the test, and charge the battery fully.
Remove all 4 spark plugs, so they are out at the same time.

If you didn't open the throttle, you could do the test again, you might get different readings.

A magneto makes it's own power, it is not connected to battery power.
Don't connect battery power to it.
The ignition switch has 1 wire, the switch grounds the magneto to stop the engine.
Like what was said above, don't turn the magneto so it snaps and makes spark if it it disconnected from the spark plugs, it can damage the magneto, the spark has no place to go with the spark plugs disconnected.

If something is wrong with the magneto, you can repair it yourself, you don't have to buy another one, unless it is in bad condition.
The magnetos work if all their parts are good.
Some people on here like them, and some don't, I guess.

[AHS]

Hi,
I would open the throttle fully before doing the compression test, so the engine can get air for the test, and charge the battery fully.
Remove all 4 spark plugs, so they are out at the same time.

If you didn't open the throttle, you could do the test again, you might get different readings.

A magneto makes it's own power, it is not connected to battery power.
Don't connect battery power to it.
The ignition switch has 1 wire, the switch grounds the magneto to stop the engine.
Like what was said above, don't turn the magneto so it snaps and makes spark if it it disconnected from the spark plugs, it can damage the magneto, the spark has no place to go with the spark plugs disconnected.

If something is wrong with the magneto, you can repair it yourself, you don't have to buy another one, unless it is in bad condition.
The magnetos work if all their parts are good.
Some people on here like them, and some don't, I guess.

My buddy Dave has the compression tester. I know that all the plugs were out when we did our test. The throttle was closed... now I know! Once I get it running; gas mixed with seafoam, will the compression numbers rise? The rings going up and down, the valves opening and closing. I would think the compression numbers would rise by a couple lbs. what do you think?

[Clemsonfor]

Assuming there is a stuck ring or two. And you run the tractor and work it and if it frees up a stuck ring I think the numbers will go up. If this tractor has been run all along before you got it (I don't remember what was said at this point) it probably won't make any difference sin e any ring if it were going to be able to be free would already be free from running. But if it sat for years and years they could be stuck and get free and increase compression results.
If this tractor sat for a long time don't forget to prime the oil pump first to make sure you have oil pressure.

[AHS]

Assuming there is a stuck ring or two. And you run the tractor and work it and if it frees up a stuck ring I think the numbers will go up. If this tractor has been run all along before you got it (I don't remember what was said at this point) it probably won't make any difference sin e any ring if it were going to be able to be free would already be free from running. But if it sat for years and years they could be stuck and get free and increase compression results.
If this tractor sat for a long time don't forget to prime the oil pump first to make sure you have oil pressure.

Ok, I have found the hole. How much oil do you have to put in there? I was doing it by a squirt can! (Aka a long time!) I guess I could try a piece of hose what do you use?

[Clemsonfor]

I used on old fashioned oiler can. The finger pump kind. It took a few fillips of it before it was full. It will run out the top when done. It took a few, I don't know 6 to 8 oz maybe?

[AHS]

I used on old fashioned oiler can. The finger pump kind. It took a few fillips of it before it was full. It will run out the top when done. It took a few, I don't know 6 to 8 oz maybe?

Ok!

[AHS]

The previous owner said “it would die about every 30 minutes or so”... And I have found out why.. I took the cover off the coil, and it looks burnt, bubbly and no good at all! So, the coil cover came off a bit tightly. Do I need to unbolt the two bolt for the generator and slide that over, to remove the coil? I’m doing points, condenser, rotor button and cap. Do I need to have it on TDC #1 when doing the points?

[Cubfriend]

I just had my magneto checked out at the Barnyard Bash. Gary looked at it for me and there wasn’t much wrong with it. It had no spark in the beginning. Everything inside looked pretty good. Gary just cleaned the points and then it had good spark. It will need a new distributor cap. The real test will be to put it on a tractor and run it for an hour or more to see if the coil breaks down. I give Gary a BIG Thank You for his help and knowledge of Cub electrical systems. Good job Gary! (Magneto point gap is .013)