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What do I need to know about IH H4 Mag?

1

1939farmall

Member
I know a lot of people would ditch the mag for a distributor and coil set up, but I think Im going to keep this M original at least for now and see how it does. To that end I went on the parts page here and ordered new spark plug wires, cap, rotor, points, condenser, and coil cover. That and a vague memory of my dad cussing the mag out on the M we had at home when I was a kid pretty well sums up the knowledge I have on the International Harvester H4 magneto. What do I need to know? How do I test it? It should have an impulse spark for startup right ? I guess I dont have an exact question, just looking for any information I should know before we start messing with it. Thanks guys.
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about all you need to know on those mags is to have the points set to spec at .013. make sure the rotor is good , give the front mag brg. a shot of oil once in a while and the rest is pretty much trouble free. i have seen some old mags that sat 30-40 years and still had spark and started the tractor. plus you dont need a battery. mag tractors were always easy starting when things were kept up.
 
Keep the magneto, I knew nothing about magneto , I bought the blue ribbon technical manual off eBay ,read it and repaired three magnetos .
Magnetos very easy to work on . You wont have a problem.
You can get parts and get advice from Brillman s .
To much stuff to change to convert to distributors. Not worth it .
 
rustred,
I'm not looking forward to learning how to replace points on my IH mag.
How do you get to the points and condenser? I'm guessing you have to totally dissemble.
 
(quoted from post at 06:34:02 08/03/21) rustred,
I'm not looking forward to learning how to replace points on my IH mag.
How do you get to the points and condenser? I'm guessing you have to totally dissemble.
Click to expand...
he points in a magneto last a lot longer than the points in a distributor.
 
(quoted from post at 03:34:02 08/03/21) rustred,
I'm not looking forward to learning how to replace points on my IH mag.
How do you get to the points and condenser? I'm guessing you have to totally dissemble.
Click to expand...

Remove 3 screws and pull off the rotor gear drive assembly as a unit, and the points are exposed. (The drive shaft is "D" shaped and will only line up one way to put drive back on, so long as you don't remove the TWO screws holding the cover over the rotor drive gears and get them out of time there will be no drama in simply accessing or replacing the points.)

There's a little cover on the engine side of the mag the condenser is removed though, to unfasten it the coil cover has to come off, then a a screw loosened to release a "tab" that secures the condenser, and finally the brass hex where the "kill" wire attaches has to be unscrewed from the condenser.

http://farmallcub.com/rudi_cub/www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/GSS-5035%20Service%20Manual%20Magnetos/index.html

You can view or print the official IH Blue Ribbon Magneto Service Manual by copying the link above and pasting it into the address bar of your web browser.
 
I don't remember much to change to distributor from nag on the 41 H Farmall. Best thing ever did. Did same thing to the 49 B John Deere. NO BODY knew how to do anything on repairing a mag and both got very hard to start from good starting tractors. With distributor had good starting tractors again. Mags went into junk pile.
 
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