Melted Coil

[Dennis (VA)]

Help! Finally, got my 9N all bolted back together after a year of sanding, painting and replacing. Got it fired up but think carb is gunked from sitting as only ran on choke. But in any case, forgot to turn of ignition switch and heard a pop and a hiss, thought it was a tire, but coil was melting. In putting it back together, what was I believed was suppose to be the resistor, square with four lugs to attach wires mount on dash, appeared to me to be nothing but a piece of fiber board with four screws. Looked home made. Tractor had a lot of baling wire fixes in its long life. This block doesn't look like picture in on-line store with metal ribs across top and three lugs. Figured it ran with this before so it must be ok. The tractor doesn't have the ceramic block with two posts that I can find.
Questions: What caused the melt down, should I order a 12V coil and what resistors would this need, Its been converted. A new resistor and does a additional resistor go in the wire from the dash to the coil? Would also be a good time to convert it to electronic ignition and thus forget about disassembly to just change points?

Sorry the post is long

 

[Dunk]

Time to learn the difference between a resistor...

And a junction block..

 

[JMOR]

Some begin to look kinda like this when they get to be around my age.

What resistance you need depends on your particular coil. Cookbook number of ohms often do not work out because the coils, even with same part number, don't all seem to be same. Best bet is to select resistance such that when connected in series with coil will yield between 3 amperes & 4 amperes(abs. max. Generally this means the original ballast A8NN12250 (~0.3 ohm cold, ~1.3 hot) PLUS an auto parts store ballast of "about" another 1 to 2 ohms.....whatever it takes to get 3 to 4 amps. Sorry, it just seems to be trial & error to achieve the 3 to 4A. Too much=weak spark, too little=melted coils.

 

[cargocult]

Would also be a good time to convert it to electronic ignition and thus forget about disassembly to just change points?


If u can afford it..yep! I converted my N about 6 years ago & have had NO problems, whereas before I had it dying often! No problems, except that the tractor will die in the most difficult/dangerous/embarassing places. It seems to me to have More Power & Starts INSTANTLY, whereas before it usta grind on 4 many seconds..now it starts up even before I can get my thumb off the starter button! (In all weather. In the summer I don't even hafta use the choke!) Nothing worse than a UNRELIABLE tractor, especially if u have a CROP in the field needing to be harvested! My opinion ONLY..I am a traditionalist, so I agonized & spaced it out for serveral years before making the step. Only regret is: I didn't do it sooner!! CC

 

[old]

Would you believe any of them will melt the coil if you leave the switch turned on. If the points are closed which they are most of the time when the engine isn't running the coil get hot and will burn its self up. When running the points open and close and give the coil a very short brake so thats why if wired correctly the coil doesn't burn up but just sitting there with the key on you burn them up. I've seen the round can type explode because of the key being left on and boy what a mess of oil and wire when that happens.
Hobby farm

 

[Bruce (VA)]

"....forget about disassembly to just change points?"

What do you mean by that? You do know that the distributor comes off the tractor w/ two bolts in about 3 minutes to replace the points, right?

I've got 3 N's, all 6v & w/ points & never have had any reason to convert them to 12v or to consider EI. I can replace a lot of points for the cost of an EI. The last time I replaced the points in my 1950 frontmount was May, 2004.
50 Tips

 

[Dunk]

A set of points will run in mine for years also...

 

[Bob]

The Pertronix EI is just like the points, in that it will be "turned on" if the engine stops at a certain point, and heat itself AND the coil to dangerous levels with the switch left on.

 

[Downeaster]

I did the same thing. A month later I was driving the tractor and it missed and sputtered and died. Had to pull it back to the ranch. Found a piece of solder from the burnt out coil shorting out the points. So take a good look for any melted solder in the distributer. Good Luck

 

[old]

Bob I knew that I just didn't add it into my post LOL.
Hobby farm

 

[Bob]

My reply about the Pertonix unit wasn't really directed at you, at all.

I was just making the point that the "EI" isn't a "cure-all" for "BLEMS" who can't remember to shut the ignition switch "off" when the tractor stalls!

BTW, the Pertronix "Ignitor II" units, for those applications where they're available, are "smart" enough to shut down the primary coil current when it senses the engine is no longer running, or at least cranking over.

 

[souNdguy]

I'd get a new coil, and then add the correct resitor to it till ya had between 3-4 amps of primary current. Don't matter 6v or 12v coil.. choose whatever ( if ya have a 12v conversion ). Try ressitance values from 0.5 ohms to 2.5 ohms depending ont he coil you got. Many different coil makers and we are seeing many ohm value coils come out due to overseas quality control.. etc..

Soundugy

 

[Phil (NJ,Az,Sask)]

Recommended:
The OEM ballast resistor part # A8NN12250 and additional Resistor part # 8NE10306 (.5 ohm) with the 12 volt coil. All available from this Board

Note:
If you use the OEM Ballast # A8NN12250, in any Combo, you will measure ~3 amps but NEVER 4 Amps. The OEM Ballast is a limiter which makes it hard to select the correct additional Resistance using current measurements alone. It will confuse you & me

Not recommended:
If you chose to use ALL auto Fixed ignition resistors in a combo the current is not limited and you could get any amount of current (3-6) You are the Master of your own Poison.

JMHO

 

[Jim WestTN]

My 8N is running the same set of points that were in it when I got it February 2003

 

[Dennis (VA)]

Thanks for all the help and especially the pictures. As far as disassembly for points, I guess I'm not as dexterious as I used to be. Have a hard time getting my fat arms past the dog legs. Again, thanks and thanks for this site!

 

[Hobo,NC]

I have had good luck with the OEM resistor and a ICR-23 (1.2 ohms) wired into the circuit. thanks to Phil (NJ,Az,Sask) that hung in their with me on my quest to answer a unknown problem that had been keep a secret for 2 long I ciphered it out.
For the most part their are 2 many scenarios for the DIY to figger out. Theirs been good advice give'n but none that tell ya it needs to b checked at 14.5 Volts were its at when its run'n and the battery is B'n recharged. If i did not have the equipment as most don't I would set the points closed,,, install a battery charger and check that i had 14 to 14.5Vs at the battery then check voltage at the top terminal at the coil,,,, shoot for 7.5 volts to 8 that will git ya in the ball park in a seat rite behind home plate. If a 12V system is rite it will kick a 6v systems arse day in and day out and live as long if not longer