Hi all. I have a 1940 or so B with a FMJ mag. This tractor hasnt been started in at least 13 years, so there are probably a number of issues, but the first item on the list is to verify the mag is good. We werent getting a spark at all so I took it off the tractor. I replaced all the easily replaceable parts inside and put it back together. Now I get a good spark on 1 and 4, but nothing on 2 and 3. I think this is because my impulse is only tripping once per revolution, so is not tripping at the 2 and 3 locations. Is it correct it should trip twice per revolution? If so I think my next step is to disassemble the impulse coupler, but I cant find any good info on this part of the assembly, what I might do once I get it off, or what kind of problems I might have getting it off in the first place. Any sort of help or advice is greatly appreciated!
- Thread starter lodgera
- Start date
Email me for impulse coupling details. Link is at the bottom of my web page. Yes, you need two impulse trips per revolution of the mag.
My web page
My web page
mdm1
Member
- Location
- Onalaska,WI
I just used tour web page for my magneto. Very good and valuable info. thanks!!!
mdm1
Member
- Location
- Onalaska,WI
oops your
tractorguy2
Well-known Member
If you put the magneto in the vise and watch the impulse dogs contact the stop pin. you can tell if they are working without disassembling the impulse coupler.
It may be the impulse pawl sticking some but when I have had spark on one or two plugs and not on the other s I found a bad cap. some caps I got working by twisting up steel wool into a pencil shape and cleaned the cap terminals and they worked. When I had a sticky pawl it didn't repeat the same every time.
Thanks all. It seems that there is some wear on the stop pin, and probably also a bit on the pawl that was not catching. Both pawls are pivoting easily, but the one was just slipping past the stop pin, and
in fact I could manually manipulate the impulse coupler and actually get both pawls to slide past the pin. I turned the pin slightly (15 degrees maybe) so the pawls are now contacting a previously untouched
part of the pin and voila, works every time.
in fact I could manually manipulate the impulse coupler and actually get both pawls to slide past the pin. I turned the pin slightly (15 degrees maybe) so the pawls are now contacting a previously untouched
part of the pin and voila, works every time.
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