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H4 Farmall Magneto Rotor drive

D

DanHoman

New User
I was recently given an "H" Farmall. According to the serial numbers I checked this site and discovered it was manufactured in 1948. (using this site for my information) I checked the spark, and I am getting intermittant spark. The rotor (inside the mag) is loose and wobbly on the metal shaft. I removed the two screws which hold the rotor drive and checked the small gears and they appear good. However, I am not sure if I got them properly aligned when I put the rotor drive back in place. So my question is; 1.) does anyone know how to properly time the two small gears for the rotor drive? 2.) is it "normal" for the rotor button (disk type) to wobble on the shaft? (the rotor appears to be in good shape, and not worn) Any advice is helpful because I am a John Deere guy, and have not much experience with Farmalls.
 
Follow-up on the H4 magneto. I crank it over holding the coil wire next to the engine block and get a continuous nice blue spark from the coil wire. It will jump approximately 3/16 to 1/4 inch.
 
Its not uncommon for the rotor to be loose but it will still work ok. Now i timing the rotor. For me its easier to have thq mag off turn it counter clockwise till it stops then look at the position it points it should line up with the tower on the cap. The 4 positions are like looking toward the mag 2 4 8 10 you will need to mesh those gears till you get it rite. You can make a mork on the body where the tower is also and time the gears whil the mag is on the tractor. You dont care about spark from the coil now you need the rotor lined up with the cap when it does fire. You mite need to get a new rotor as it mite fit tighter on the shaft. I have the parts if you need them and so do others on this site.
 
Actually I solved all the problems with replacement parts. I ordered a rotor drive off Ebay, and then bought a tune up kit from TSC. After I replaced the rotor drive and timed it to point to the #1 plug tower on the magneto cap it fired and ran good. There is no slop or slack in the rotor button now. It had just worn out from years of sue I suppose. I am planning of replacing the carbon type wires with copper type wires, and the D-18 Champion plugs with AC Delco C-88 spark plugs. I find the C-88s work a whole lot better in my John Deere "A"
 
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