There is no such thing as a 39 md.MD's were not built until 1941. First md was built jan.41 serial number 26145. All md's until early 1952 has magneto style ignition. Once the supers came out in spring of 1952 they started using distributors. The tractor you are referring to is either something someone built or put together out of multiple tractors,or the serial number is not being read properly. Jim.
 
OK I will check the serial number Thank You. The owner does say it has the deck with the channel in it though. I suppose something was switched here. Do you know why they kept the mag instead of electric ignition on those until 52
 
The magneto is perfectly dependable and requires no battery to run. Batteries in the 40s were no where as dependable as they are today. I owned an MD for several years. Always started easily on gas with the magneto ignition.
 
A good mag is better then a distributor any day of the week in my opinion. I have 2 md's here 41 and 51 and a farmall h. All have mags and all 3 are hand started year round. I hate buying batteries and if everything is timed right they usually start on 3 or 4 pulls of the crank. Just got a smd with distributor and not looking forward to the electrical work. Also the h4 mag on a diesel is counter clockwise rotation. Gas engines are clockwise. Sounds like someone swapped out deck plates. Pics would be nice. Jim.
 
Most all md's were mag. Don't start seeing many distributors until the super md's. Even then mags are listed as a option in place of distributor.
 
I totally agree with you. I bought a 46 MD in 1966 and have never touched the mag in the almost 50 years I have owned it. It always starts right up on gas. Al
 
(quoted from post at 05:18:42 02/26/15) I totally agree with you. I bought a 46 MD in 1966 and have never touched the mag in the almost 50 years I have owned it. It always starts right up on gas. Al

How has the rest of the engine been over that amount of time?

Thanks,
Dan
 
Even this may 1940 prototype didn't have a slot type transmission cover. If you look close the round pipe seat frame can be seen along with the front mounting bracket. They did change the fuel filter set up and starting switch over linkage along with a few other things.
One reason the MD wasn't changed to the distributor ignition until after the others, was the others with correct timing curve distributor gave better, smoother engine performance from idle to full RPM. On a diesel with only one speed on gas that wasn't very important.
Can't claim for sure that it was built that way. But had a MD built in late feb. 52 once with a distributor and the correct manifold parts for a distributor.
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I owned a Super MD years ago with a distributor. When you switched from gas to diesel it had a switch if I remember correct on the end of the manifold that rotated and cut power to the distributor. With a mag, does it keep the plugs firing?
 
Larry, No the plugs don't fire when you switch to diesel. Just like on the distributor MD's, there is a similar switch in the manifold that grounds the mag when in diesel position. This is probably why the mag points and plugs last for years. Al
 

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