1940 farmall h magneto ground

I bought this tractor and the owner told me it would not start because the ground wire was not hooked up from the switch to the magneto. This is a early magneto from what I can tell and it has some kind of external switch that is missing between the two screws. I'm wondering if I hook to one of the screws from the switch will it ground the magneto without the missing part. I don't see the external switch offered anywhere. Does anybody know? Craig

This post was edited by Lottie1 on 01/09/2023 at 01:49 pm.

From long-ago memories, magneto ignitions
are grounded through the ignition switch
to shut them off. Lack of grounding
inhibits shutdown, not running.

that is not the reason it wont start. the ground wire is only used to stop the tractor or cut of the spark. you dont need anything hooked up
for it to run. all that switch is a one wire switch for ground. the distributor tractors have a 2 wire switch. just hook up a piece of wire
to the mag connection and kill it that way till u find a switch. your photo dont work.

Below is a drawing of the ''choke cable''-operated kill switch, Key # 96.



Lacking those parts, you can simply run a wire from the brass ''nut'' between the mounting holes for the missing switch to a one-terminal push-pull mag kill switch mounted near the driver.

WHATEVER you do, NEVER supply battery voltage to the magneto!

That ground wire is only to shut off a running tractor, Will run just fine
without ground wire and just kill engine with the brakes or go up to mag
with something like an insulated handle screw driver and just touch screw
the ground wire fastens to and body of mag and it is shut off The ground
wire is only so you can shut off engine without getting off tractor. Now if
it would happen to be a distributor it would need 2 wires to the switch, one
to switch to mag, other from battery s A grounding switch only has place for
one wire as the mount for the switch serves to complete the ground from mag
source to switch. Now if battery ignation then you need a power source from
a battery and the H is supposed to be 6 volt positive ground to switch and
then from battery to distributor. The owner sure does not know anything
about the tractor and I dought if he ever heard it run not knowing any more
than he does. We had a 41 H that Grandpa bought in 1948 and it did not have
hydrolics, Granda passed away in 77 and we in about 78-79 added the
hydrolics to it to operate the haybine And then in 84 traded it off on a
bigger tractor. If he thinks it will not start because of a broken wire on
tye mag I would wonder what all else is wrong with it. Always pulled a John
Deere No.52 2-12 inch plow with it.

(quoted from post at 15:20:26 01/09/23) Below is a drawing of the ''choke cable''-operated kill switch, Key # 96.

Lacking those parts, you can simply run a wire from the brass ''nut'' between the mounting holes for the missing switch to a one-terminal push-pull mag kill switch mounted near the driver.

WHATEVER you do, NEVER supply battery voltage to the magneto!

Click to expand...

hat would be a very early h-4 mag, didn't the just came on the '39 and early '40 model Farmalls? I have one to put on my '39M someday.

Wonder if you are getting spark?
Remove a spark plug wire, stick a
good spark plug in it, hold it
next to the block and turn motor
to see if it sparks.... If not
report back and we can
troubleshoot. Could be as easy as
filing the points.

thanks wore out and everybody else for the great pics and info. I am learning more about this old tractor. Hopefully I can get it running.

From what you say about the owner it may not even have any pistons in it.