Ford Model 600 coil

I have a Ford Model 600 that has been converted to 12 volt before I bought it. I started to work on it last year and got side tracked. I rebuilt the ignition including the coil at that time. The tracto ran, but needed a carburator rebuild and I didn't get around to it until this week. Basically the tractor sat for a year. I got the carburator rebuilt this week, but the tractor has no spark. I replaced the points, condensor, plugs and plug wires. It still wouldn't start, so I tested to see if I had current to the coil, and I do. However, I have nothing coming out. I suspect the coil is bad. When I bought the coil, the guy told me I didn't need the resistor block, but I am not so sure at this point. I suspect that I may have installed the wrong coil for a 12 volt system, or that I needed the resistor block. Can anyone tell me what coil to use with a 12 volt system? I saw a post that mentioned this coil NAPA IC14SB. Do I need a resistor block to use this?
Thanks,
Sam Hottinger

If the coil is a 12v coil on a 12v system u do not need a resistor I just got thrue lerning that the hard way thes old tractors have run for decades on Henry's designs and most parts now a days aren't as good as the old ones BUT the systems thay have been improved upon in brace the 21st century I would check the wires in dis running from condenser to the point make shuer it isn't grounded out and the wire on the stud on dis to coil check the cap on dis make sure the contacts are not wore done check rotor for wear hope this helps

IC14SB from Napa will work without a external resistor.
Wire the + side to switched power (power only with key on) and the - side to the distributor.

>I tested to see if I had current to the coil, and I do. However, I have nothing coming out.

I don't know how you did your test, but it sounds like you need a brief primer on ignition systems. I'm going to assume you have a voltmeter of some sort.

In order to get a spark from the coil, the points must open and close. The voltage you see at the primary coil terminals will change depending on whether or not the points are open. We will measure the voltage referenced to ground.

Start by checking the voltage on the battery (+) side of the coil. It will probably be battery voltage (~12 volts) but could be less if the points are closed and there's an external resistor in the circuit. If the voltage is less than six volts, something is wrong.

Assuming you have good voltage on the positive coil terminal, go to the distributor (-) side. If the points are open, you'll see the same voltage as on the + side. If the points are closed, you'll see zero volts to ground.

Now what you need to do is see if the points are opening and closing. If they were open in the previous step, bump the starter until they close and the voltage goes to zero. Now remove the distributor cap, rotor, rotor clip and dust cover. Using a screwdriver and being careful not to short out the points, you should be able to open and close the points, causing the voltage on the distributor side to go from zero to 12 volts. (Pry against the plastic rubbing block to avoid shorting the points.) If you can get the voltage to go up and down when you open and close the points, your components are probably OK. You should also be able to get a spark from the coil wire to ground whenever you open the points.

Now if you can't get the voltage to change when you open and close the points, figure out why. If everything is good so far, you need to make sure the points are gapped properly so the distributor cam can open them. Bump the starter until the point rubbing block is centered on the top of a cam lobe. If the points aren't slightly open, then you need to regap them.

Now as far as which coil you should have, the tractor should be able to start and run with the original coil whether or not there's an external resistor. But the points will quickly burn out without a resistor in the circuit, and the coil will eventually fail as well. (The original "six volt" coil and a coil marked "external resistor required" are essentially the same.) Now if you have BOTH an external resistor AND a "NO external resistor required" coil, it's probably not going to work. You'll be able to see if there's an external resistor by checking the voltage at the battery side of the coil WITH THE POINTS CLOSED. If the voltage there is significantly less than battery voltage, there's a resistor in the circuit and you shouldn't use a "no external resistor required" (e.g. IC14SB) coil. But if there's no external resistor, then the IC14SB-style coil is the one to use.

Thanks Guys, this was very helpful
SAm

so you bought a coil a year ago. havn't run the tractor and now think it's a bad coil?

unless you got unlucky and got a bad one outta the box.. i doubt your coil 'spoiled' from setting there a year.

put a test lamp inline with your coil and roll the engine over with key on. lamp should blink.

don't throw any more parts at this issue till you understand how it works and how to troubleshoot it.

I replaced the coil. The tractor still didn't start. So I took the condensor out and put it in my Ford 2000 to test it. The Ford 2000 started. Put the 2000's condensor in the 600. The 600 started and runs like a top. I have no idea what I did different, but something must have been shorted out. Thanks for the input.
Sam