Big question

Connected fuel. Turned ignition switch. No firing...doesn't fire up.

Removed resistor to coil. Direct 12V lead to coil. Engine fires up (boy does it sound good too).

Put resistor back on. Turned ignition switch. No go. Direct contact again to coil...no resistor...fires up (oh man, she sounds good).

Tried getting a meter reading: Set meter (this time) at 50 DC. Reading in at ballast resistor 30-40. Reading at other end of resistor...about the same. (I don't know how to set and read this meter all that well).

Changed resistors to a ballast resistor described in the Farmall 12V conversion article on this site. Same thing...30-40 in, and 30-40 out and same situation...attached the resistor...no fire-up. Remove the resistor...fires up. sounds good too. Help again? -9N'er

I do know that the new condesnor is a 6V, and it is shorter in length than the one I replaced.

I do not know if the coil is 6V or 12v.

Here are the questions:

1. Let's assume I have a 12V coil...and a 6V condensor...would that cause the weak spark?

2. if I had a 6V coil, and a 6V condensor...the spark should be correct. ?

3. If I purchase a new coil: should I get a 12V coil and matching condensor, or 6V coil and mess around with resistors?

I tend to go 6V because I will convert at a later date. Looking forward to these replies. thanks so much 9N'er

About your coil, if I assume it is a 12V coil. Then there shouldn't bee a resistor between it and batt/alt voltage. It is intended to see 12V, and that's why you hear that purrrrr (nice, huh?) when you jumper out the resistor.

By the way, I'm sure the ignition system doesn't affect the looks of the tractor that much. Why don't you post a photo. Your 9N has become something of a legend around here. It should be on that "free calendar" thing. I'm sure Kim would agree.

Good luck.

Old Ag
'41 9N

If I understand correctly, you have the original 6V system on the tractor. That means you should see around 6.5VDC generator output going to the ballast resistor. I know the coil is supposed to get around 4VDC and draws about 3A. Doing the math (V=IR), that means you should have a 2.5VDC drop across the ballast resistor with 3A current so you need about a .8 ohm resistor that is capable of handling at least 7.5 watts (P=VI). I recently bought a 1 ohm/50 watt resistor from radio shack to use as a ballast.

To check your system, read generator output voltage or battery voltage (if you don't have an auto ranging multi-meter, select a 0-10 VDC scale). Then read voltage to the top of the coil with the ignition on. Subtract the latter from the former, this gives you voltage drop across your ballast resistor. A voltage drop in excess of 2 or 3 volts indicates that the coil is not getting enough current and is generating a magnetic field too small to give good spark. Check the entire circuit from the terminal block through the resistor to the coil using the ohm-meter on your multi-meter. The only noticeable resistance here should be at the ballast resistor and nowhere else. Also, you may need to check the coil/condenser/points part of the circuit to make sure there are no "leaks" of power to ground. Good luck with it.

I hope I have half your strength of character when it comes time to fix up my tractor.

Old Ag
'41 9N

I didn't run the engine long at all. And my starting attempts were short (less than 15 second cranks on the starter). Could I have burned the points if I was pumping too much current into the distributor?

Later this morning, I'll try to get a better meter reading and I suspect it's the wrong resistor, but what throws a loop in that logic is using the old resistor and I get the same results...???(worked fine before).

But for now, I had to think through some of my steps and this is what I remember (my head is floating out there too...I ran my dog into the clinic last night and put her to sleep...too much pain for her...couldn't stand it any longer...sad :(

At one point through this trial I set DC at 10. Got a 9 reading at top of resistor. Turned ignition on. Got a 3+ reading at top of coil and at other side of resistor.

Wouldn't fire. Replaced the resistor (I got it from the guy at the Auto Electric store...who said that he has used these on another old tractor...and it is rated to drop V's to 4.2) with the NAPA ICR13 ceramic resistor (it's about 1.5 inches long two poles (one in, and one out). Same results...same reading. That's when I just connected the direct starter/ignition line to the lead of the coil. Turned ignition (holding these two wires together) fired up (I pumped my fist several times). Pulled wires apart, motor shutdown.

Then I put the original round ceramic resistor into the circuit. Same results.

I'll try to get a meter reading while it is cranking over...but hard to do...it's a long reach while holding the key open...but I can rig something up to hold one lead to ground and the other to the top of coil. I have the moring free before I go to work...will see what I can do. -9N'er

do you know where I can get a front wheel fo a 2n?

Unfortunately, as I kept reminding my ex-wife, I flunked mind reading. So I really can't make much sense out of your meter readings except ya' gotts more volts than the 12 volt battery ya' started with. "its a magic" (grin).

Maybe you can find someone to tutor you in the fine arts of reading and using a meter.

Everyone is trying to help, please report back with the "real reading" at the coil terminal with the points closed and open. (hint) You should have 12 volts with the points open. ..... .Dell