Registered: Mar 2008
Location: Western N.Y.
Posts: 4005

I know there must be some experts on here....
Starts cold and purs like a kitten, as it warms up it starts to miss and then quits. Tractor has been switched over to 12 volt, has a good battery and is chargin, new carb, when it quits the carb bowl is full so its not runnin out of gas. Im thinkin maybe coil, any other ideas?

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Registered: May 2005
Location: virginia
Posts: 7043

did you put 12 volt coil on . or put resistor in line .if you didn't do one or other will burn coil

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Registered: Mar 2008
Location: Western N.Y.
Posts: 4005

It has a 12 volt coil, my son just bought this tractor a couple weeks ago and the guy did say he had had to replace a couple coils, im wondering if even with a 12 volt coil if it should be knocked down to 9... it has a simple one wire alternator with internal regulator that puts out about 14 which may be burning the coil.

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Registered: May 2005
Location: virginia
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I DON'T KNOW ABOUT THAT THE OLD 9N I HAD AB RESISTOR IN THE LINE TO COIL AND 6V COIL WORKED FINE. IM NO EXPERT JUST TRIAL AND ERRO

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HOME OF TREETALKIN
BLACK & TANS
CORKY CROWDER
BRANDON MAYO
LINDA CROWDER
PR TREETALKIN LITTLE SASSY
TREETALKIN TROOPERS BLEW
TREETALKIN RANGER DANGER
TREETALKIN LIL SHOOTEM UP JAKE
GRCHPR TREETALKIN NIGHTHAWK GONE BUT NEVER WILL BE FORGOTTEN R.I.P.

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Registered: Oct 2013
Location: Maryland
Posts: 2633

Usually when they do that it is a sign that the valves may need to be adjusted...as the engine runs the valves loose lash {clearance} when it looses enough lash as the engine heats up the valves can float {not close completely} which will cause a miss. Back when everything had solid lifters and adjustable valves it was done as a part of routine maintenance. These days most people don't even know that the valves are adjustable, let alone actually taking the time to adjust them.
They should be done every year. That tractor was made from 1939-1941, so the "youngest" it could be is 74!!!! I doubt the valves in that tractor have been reset 74 times....it could probably stand to have it done even if that aint the problem.
If it's the coil doing it, you can check that easy enough with either another coil to switch out while the engine is still up to temperature or get it hot and remove that coil. Pack it in ice for a few minutes and reinstall while the rest of the engine is hot. See if it purrs again while the coil is cold.
There are several other things that can heat up and cause trouble. Those carburetors were troublesome when they got to be 25-30 years old...this one is double.

Edit: I would also check the ignition resistor...if I remember right the tractor had a separate resistor made like in a ceramic insulator {cant remember the name, been out of it for a while} sometimes when a 12 volt conversion is done a resistor wire is also installed. Heat increases resistance and you may find that the coil ends up not getting enough voltage when everything gets to operating temperature. I would check the coil voltage when you first start it cold and again when it starts to miss.
Another edit: Ballast resistor....it's coming back to me slowly!!!! You can use either/or, but you do not want/need both.

Last edited by msinc on 10-31-2015 at 11:13 PM

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Registered: Apr 2008
Location: Reelsville , Indiana
Posts: 1124

quote:

---

Originally posted by msinc
Usually when they do that it is a sign that the valves may need to be adjusted...as the engine runs the valves loose lash {clearance} when it looses enough lash as the engine heats up the valves can float {not close completely} which will cause a miss. Back when everything had solid lifters and adjustable valves it was done as a part of routine maintenance. These days most people don't even know that the valves are adjustable, let alone actually taking the time to adjust them.
They should be done every year. That tractor was made from 1939-1941, so the "youngest" it could be is 74!!!! I doubt the valves in that tractor have been reset 74 times....it could probably stand to have it done even if that aint the problem.
If it's the coil doing it, you can check that easy enough with either another coil to switch out while the engine is still up to temperature or get it hot and remove that coil. Pack it in ice for a few minutes and reinstall while the rest of the engine is hot. See if it purrs again while the coil is cold.
There are several other things that can heat up and cause trouble. Those carburetors were troublesome when they got to be 25-30 years old...this one is double.

Edit: I would also check the ignition resistor...if I remember right the tractor had a separate resistor made like in a ceramic insulator {cant remember the name, been out of it for a while} sometimes when a 12 volt conversion is done a resistor wire is also installed. Heat increases resistance and you may find that the coil ends up not getting enough voltage when everything gets to operating temperature. I would check the coil voltage when you first start it cold and again when it starts to miss.
Another edit: Ballast resistor....it's coming back to me slowly!!!! You can use either/or, but you do not want/need both.

---

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Registered: Oct 2013
Location: Maryland
Posts: 2633

Another thing just hit me when I read your post Justin...the original 9N-2N-8N line of tractors had a positive ground system...check to make sure they either reversed to a negative ground and also reversed the coil or not when it was converted to a 12volt system.

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Registered: Jul 2012
Location: Rutledge,TN.
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My 8n acted similar to what you're saying. I put a new voltage regulator on it, and it hasn't acted up since.

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Registered: Mar 2008
Location: Western N.Y.
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UPDATE... Rebuilt the carb, fresh plugs and wires, new points and condensor.... it doesnt quit anymore but still runs rough under load when warm(brush hog), after 10 minutes or so it will miss some and backfire once in a while. Thinking now maybe the governor needs rebuilt?, if that doesnt work adjusting the valves will be next, for a simple old machine this thing sure is a pain, acts to me like it is out of time but there is no way to adjust that.
Thanks for the tips, any other ideas?

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Registered: Oct 2013
Location: Maryland
Posts: 2633

quote:

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Originally posted by john Duemmer
UPDATE... Rebuilt the carb, fresh plugs and wires, new points and condensor.... it doesnt quit anymore but still runs rough under load when warm(brush hog), after 10 minutes or so it will miss some and backfire once in a while. Thinking now maybe the governor needs rebuilt?, if that doesnt work adjusting the valves will be next, for a simple old machine this thing sure is a pain, acts to me like it is out of time but there is no way to adjust that.
Thanks for the tips, any other ideas?

---

Last edited by msinc on 11-05-2015 at 11:30 PM

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Registered: Mar 2008
Location: Western N.Y.
Posts: 4005

Thanks for the help guys, problem solved, turned out to be the (supposed to be)insulated terminal inside the distributor where the points connect to the coil wire. It was leaking to ground, so after it ran a few minutes the coil would stop fireing.

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Registered: Oct 2013
Location: Maryland
Posts: 2633

Glad to hear you got her fixed Mr. Duemmer

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Registered: Oct 2007
Location: Cortland New York
Posts: 1221

CAN OPEN AND CLOSE PROPERLY JUST LIKE WE HAVE TO DO WITH OLD BOAT MOTORS HOPE THIS CAN HELP

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