In Reply to: Re: Ford 2N Ignition Coil Circuit posted by Phillip G. on August 09, 2022 at 13:11:04:
I was sort of being flippant about asking questions, but that is why we are here Phil. Gotta be thick skinned if'N ya wanna be an N-Owner!!! Anyway, I usually always first ask too if you are using 6V or 12V like JMOR did. Either system is fine, will run and work just fine, as long as the system is wired correctly for that setup. Each setup has its own PROS & CONS. Many get into trouble when their 6V system becomes non-starting/non-running and they 'think' the only solution is to switch over to 12V. If the system won't run on 6V, why do you think it will on 12V? SEE JMOR's Wiring Pictograms for every correct way to wire them. FORD did not ever use 12V until the late 1950's when the Hundred Series diesel models were introduced. There are no OEM N-Series manuals that show a 12V setup. Many fellas start tinkering with their electrical systems when problems arise and 'think' they know what to check, and what the data should read. This is where they get into trouble as they start probing their VOM for current and voltages and have no idea where to check, why, and what they should be. Worse is the guy who starts probing with his Idiot Test Light and shorts out something. Always use your VOM set to CONTINUITY when testing wiring. A test light requires power and you do not want power to the circuit while tracing wiring. I advise to first disconnect the battery, take it to a shop to be tested. Many times it is the simple basic things that bite us. First thing is to test the battery. The battery is the heart of every machine. You need a strong battery to:
1. Close the solenoid
2. Spin the starter
3. Engage the Bendix
4. Provide voltage to the coil.
As the battery gets weaker, the first thing to fail is your spark. If the battery is almost totally dead, all you will hear is the solenoid clicking.
The more current you use to spin the starter, the less you have for the ignition.
Always get a good brand battery – DEKA, INTERSTATE, EAST PENN/DURACELL, EXIDE, are the best. Low budget ones tend to have poor lifespans so you end up buying a new one every few years. A 6V is a GRP 1 type and a 12V uses the GRP 25 or 35 Type. Some batteries are bad out the door of the parts store. Once everything is right with the world, you should invest in a float charger like the Battery Tender Jr to maintain a full charge when tractor is idle and when you need it.
The second most often usual suspect of a non-starting machine is whether or not your setup is using a fan belt tension device. Without proper fan belt tension, you will never charge the battery, regardless if using a 6V system with a GEN & Cutout (or a VR with an 8N) or a 12V setup with an alternator. 12V conversion kits sold today sometimes include a belt tension bracket. Check before you buy. It matters.
The third possible root cause of non-starting is the distributor. The FORD Front Mount is often misunderstood and can be set up wrong. Mounting the correct way is very important and if done wrong will damage the base and cause issues. Cam shaft end and Cam & Weights on unit are offset and must mate up male to female. Rebuilding the front mount is an art. It must be done with unit on your bench, cleaned, and points gapped at .015” then timed correctly. Use a good set of points such as the Standard Ignition/Blue Streak FD-6769X set, NAPA sells them. The rebuild requires ensuring the copper strip is connected correctly to the points. Replace the condenser with the new one in the kit. Some have replaced the condenser many times when problems arise thinking they have a faulty part. How do you know how to test? Never assume. The only way to verify a condenser is good or bad is with a special test machine. I can say honestly say I have never had a bad condensor. Ensure the Coil pigtail is properly making a good contact.
Next, test with your VOM set to CONTUNUITY like this:
1. Coil off, cap off, points open, with one probe on the brass screw and the other probe on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere else because the points are grounded.
2. Coil off, cap off, points open. Place one probe on the brass screw and the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor. As the points open & close, you should have continuity (closed) and none when they open.
3. Put the coil on the distributor, cap off, points open. Place one probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!
4. Coil on, cap off, points open. Place one probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have NO continuity!
When the rebuilt distributor passes timing and testing, it is ready to be mounted back on the engine. Take your VOM and measure your battery voltage and note it. On the Ballast Resistor, looking at the rear dash, there are three terminals and only the top two are active, one on either side of the resistor. The LH terminal only connects to the coil wire and the RH terminal is the Ignition Switch wire connection. That's it, nothing else wired on either side. The middle bottom terminal is only a semi-passive junction post. Take your VOM and set to VDC. Apply one probe (polarity doesn't matter) to the LH Resistor terminal - should be the coil wire. Apply the other VOM probe to metal ground anywhere. Ignition Key Switch ‘ON’ but do NOT turn engine over. You should see battery voltage with points open and about half that with points closed. You can open and close the points simply by tapping the neutral safety start pushbutton without key on. YES? So far all OK. Move a probe to the top of the coil post now and repeat. Pass? Yes? You are getting the correct V to distributor.
Finally, your wiring is all so important to have correct no matter if 6V or 12V. If you choose to go with 12V, you can use a 1-Wire alternator or a 3-Wire unit. Use JMOR’s Pictograms for 12V to see how each is wired. Before mounting the distributor decide if you want to use the OEM 6V coil or opt to replace with a new 12V coil. With the 6V original coil on a 12V setup, you will need to also buy a 1-OHM external resistor or equivalent, and insert it in the circuit with the coil wire. Swapping out to a 12V coil will eliminate the end for an external resistor, my personal choice. In the 12V circuit, you can also decide if you want to use the OEM AMMETER or swap it out for a VOLTMETER –see PICTOGRAMS. My personal choice is to stay with the AMMETER. Think of the movie “Apollo 13”. To fix the problem, the crew had to conserve what amps were left in the batteries. They needed no more than a 20A draw in order to restart the capsule for getting back to Earth. AMPS/current are everything, not volts, a technician says. Without it they don’t fly. An AMMETER will show a current charging and that is more important than a VOLTMETER just showing what the battery voltage is reading.
A long post but I hope to have covered all the important details on the electrical systems.