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KWRB

Magneto questions, lots of them

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I have a modest stable of 3 old IH tractors and a stationary engine. I'm rebuilding both magnetos now.

1) 1950 C with distributor and electric start and lights. I inherited this one. It's possible the electric start was added later. In fact the C either didn't have a starter, or had a bad starter when I was a kid because I remember my father crank starting it. We bought him a starter for Christmas one year. I don't know if he replaced a bad one, or installed where there wasn't one. I also don't know if he switched from a mag to a distributor at the same time. I also don't know when the 12v conversion was, but it was a home job (no wiring harness).

2) 1949 OS-4 with H4 magneto and electric start and lights

3) 1945 OS-6 with distributor and electric start and lights

4) 1945-ish LA Engine with H1 magneto

 

Question 1) Since tractors were ordered/offered with magnetos or distributors for several overlapping years, what drove the contemporary decision on whether to order a machine with magneto or distributor? I've read some people's guesses that with crank start, most customers would order the magneto. However all of my tractors have electric start including the one with a mag. It is possible however that electric start was added later for all of them.

Question 2) I'm rebuilding the H1 mag for the LA, which is about identical to the H4 mag on the tractors. I want to clean the housing. What do you recommend for cleaning/degreasing the cast aluminum housing? It's pretty soft stuff. I think I marked it up just rubbing off the serial number.

Question 3) Were magnetos painted? I'm inquiring both on the stationary engine and on the tractors. It seems strange to me to paint cast aluminum.

Question 4) How often are coils failed? The points/condenser kits are reasonable, but the coils are expensive. I'd rather not buy them if not necessary

Question 5) How does one test a coil? Presumably resistance? What would be a "good" resistance (or other metric) on an H1 or H4 mag?

 

 

 

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You need the book titled , i believe, How to restore tactor a magneto.

It covers some of the most common mags including the ih h4. Also talks about testing procedures and tools in first chapters of the book. I posted pics of book and some pages not long ago for somebody. 

Would have to go back and read coil testing procedure but its not too hard i do recall that much. Dont think you would want to replace it unless you know for sure its bad. Does the tractor run ok now or does it have issues?

The book says if a coil tester tells you coil is bad its bad, if a coil tester says coil is good it could be good or bad. Meaning it could still have a problem when at operating temps as i understand it. First thing to do if it doesnt run would be check with a meter and make sure it isnt open.

Im at work right now so i cant look at book at moment.

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11 hours ago, KWRB said:

I have a modest stable of 3 old IH tractors and a stationary engine. I'm rebuilding both magnetos now.

1) 1950 C with distributor and electric start and lights. I inherited this one. It's possible the electric start was added later. In fact the C either didn't have a starter, or had a bad starter when I was a kid because I remember my father crank starting it. We bought him a starter for Christmas one year. I don't know if he replaced a bad one, or installed where there wasn't one. I also don't know if he switched from a mag to a distributor at the same time. I also don't know when the 12v conversion was, but it was a home job (no wiring harness).

2) 1949 OS-4 with H4 magneto and electric start and lights

3) 1945 OS-6 with distributor and electric start and lights

4) 1945-ish LA Engine with H1 magneto

 

Question 1) Since tractors were ordered/offered with magnetos or distributors for several overlapping years, what drove the contemporary decision on whether to order a machine with magneto or distributor? I've read some people's guesses that with crank start, most customers would order the magneto. However all of my tractors have electric start including the one with a mag. It is possible however that electric start was added later for all of them.

Question 2) I'm rebuilding the H1 mag for the LA, which is about identical to the H4 mag on the tractors. I want to clean the housing. What do you recommend for cleaning/degreasing the cast aluminum housing? It's pretty soft stuff. I think I marked it up just rubbing off the serial number.

Question 3) Were magnetos painted? I'm inquiring both on the stationary engine and on the tractors. It seems strange to me to paint cast aluminum.

Question 4) How often are coils failed? The points/condenser kits are reasonable, but the coils are expensive. I'd rather not buy them if not necessary

Question 5) How does one test a coil? Presumably resistance? What would be a "good" resistance (or other metric) on an H1 or H4 mag?

 

 

 

I think out ofww2 that manufactures had some serious decisions to make because materials used in the war were not available. So they I think a real good job getting ther products out to satisfy a markets they had. 

Why do I think this? I only have to look at the clutch  throw out bearing on the 1948 Farmal C. It isn’t a ball bearing design .

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I have a 41 or 42 farmall A. Was my dads. When he got it, it had the magneto and no other electrics. After a couple of years he got a starter, went to install it and there was no ring gear.

it makes sense to me to use the magneto on crank start engines, but in 1950 things were starting to change for ease of operation.

After he had the tractor for five years or so it would stop running when hot and not restart until quite cold. After doing some diagnostics we decided that the problem was in the coil. It would have been about 55 years old. I replaced it for him and it still runs good today.

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Question 1 Most Farmall Cs came with 6 voltsystem , magneto, cutout relay  generator. ,with 12 volt conversion not sure what’s happening there. 

Question 4 , is my opinion that coil and condenser last long time. Still you must test them to be sure. 

That’s  it for me , all I can say ,you have to tackle one tractor at a time using a good troubleshooting practices. 

Good luck

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Plugs gap different  for Mag than Dist.

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