Question on a I.H. H4 magneto

Brent Zappe · May 6, 2014

This last week I was working on my Dads Farmall M. It has a Magneto H4 what I ran into a no spark on the engne. Checked points they looked great.Timing was on time. Found a bad wire that came out of the coil. So I order a new coil to replace the old one. My Question is Do I have to remove the Magneto off the engine to replace the coil. Can I tae the bolts out and clamp some how the magneto and trun it side to side to get to screws lose ,out. Then pull coil out and turn it back with out takeing the whole magneto out of the engine. What would you suggest. My book says there is only one way to do it but I know there is another to do this job too. Thanks Brent

hoof print · May 6, 2014

there is a screw on each side of the coil. You will have a hard time removing the in-board screw with the magneto on the tractor. It's a simple matter to remove it.

Janicholson · May 6, 2014

Just do not rotate it or the engine !!! Jim

Fullers Farmalls · May 6, 2014

I agree take it off. But mark where its pointing(the rotor) on the outside casing. I didn't do that and learned to retime a tractor the other night...

waltdavies · May 6, 2014

Before starting turn the engine to #1 top dead center both valves closed. Check for timing marks if nun then mark both mag and engine with chalk. Now remove the mag and repair it should be easy to find # 1 on the mag as you marked it.
Good luck.
Walt

John B. · May 6, 2014

When driving the core out of the old coil use an oak dowel rod. Put shellac on the iron core before installing it in the new coil. There is a way to release the impulse coupling before installing the mag back on the tractor. I always look where the rotor is pointing before removing the mag from the tractor. When re-installing the mag I put the rotor in the same position. Then I back the engine up a 1/4 turn for the impulse coupling dogs to fit into the drive gear. If you keep the engine on DTC you'll you'll have to wind up the impulse coupling until the dogs line up and you'll probably never get the mag back on because it will trip before you'll get it bolted in place. This is why I rotate the engine backward apprx 1/4 turn or just enough for the dogs to line up. Then once the mag is bolted in turn the engine forward and it will wind up the impulse coupling and trip when the engine is on top dead center. Just something I learned thru the years.

teddy52food · May 6, 2014

Ever try turning the mag backwards to where it needs to be????? Simple. Leave the engine at TDC.

teddy52food · May 6, 2014

You also have to get the condenser out the back side to get the coil wire off. Pull the mag.

Brent Zappe · May 7, 2014

Okay thank you for all of your comments. You have just told me what my book says to do. I was just hopeing that I could find a faster and easier way to do it. that friday when I working on this engine I really did not have the time to finnish this job after reading my Magneto book. I already feared that I had to pull the Magneto off to do the work. I have learned two ways to put Magnetos in to engines. Which means I better get ready to travel to parents with tools to pull Magneto out and put back in. Thank you for all of your sugguestions they really do help. Brent

Question on a I.H. H4 magneto

Brent Zappe

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hoof print

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Janicholson

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Fullers Farmalls

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waltdavies

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John B.

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teddy52food

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teddy52food

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Brent Zappe

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