IGNITION SYSTEM

All N-Series Tractors - Ford-Ferguson 9N, 2N, and Ford 8N

If you are having trouble with weak spark, no spark, or burned coils, you may find some helpful information on my new WON'T START page, or on my COIL PROBLEMS page.

If your ignition switch is more than a couple of years old, it's probably a good idea to replace it. The ignition switches are not sealed units. Moisture gets in there and corrosion starts. Any resistance added by a bad switch makes for a weaker spark. An ignition switch will nearly always test ok with a test light or ohmmeter. Checking voltage ahead of and after the switch may not reveal a problem. If there are problems with weak spark or and engine that runs good for a while then starts a random missfire, the ignition switch may be the problem.

Use spark plug wires with a solid conductor core NOT automotive resistor-core type wires. The most common resistor core wire is easy to identify. Look at the terminal ends. If the conductor core looks like cope or stainless steel wire, you are good to go. If it looks like black or dark grey fiber rope, it is junk. Solid core wires are inexpensive, extremely durable and most likely the best choice for use with early points or magneto ignition systems. Durability is extremely important for spark plug wires on a farm tractor. HOWEVER, the main exception to this is if you have "upgraded" the points to one of the breakerless electronic modules. The original solid core type wires can cause problems. The electrical "noise" generated by non-suppressor wire can cause ignition problems or complete failure of a breakerless ignition module!

The best spark plug wire choice for these tractors that have been upgraded with a breakerless ignition module is an EMT/RFI suppressor-type wire that has very small spiral windings around an insulated ferromagnetic core/strength material. The wire must be specifically designed to provide high strength, durability, and high energy delivered to spark plugs even with low energy ignition systems. Magnecor is one manufacturer that makes a high-quality spiral core spark plug wire that will work well with a breakerless module. If you still have points, just stick to the solid core wire. Spending a bunch of money on high-end wire will not make it run better.

Beware manufacturers who advertise “low-resistance”. This is basically meaningless advertising hype for suppressor-type wire. Some suppressor wire measured with an ohmmeter may show very low resistance, but still not perform well on these tractors. The high voltage spark current actually flows on the outermost surface of the core (skin effect). This high voltage resistance cannot be measured with a typical ohmmeter.

Cylinders are numbered 1, 2, 3, 4 from front to back and the firing order is 1, 2, 4, 3. YES, it's 1, 2, 4, 3. That is not a typo. Replacing wires one at a time can keep you from mixing them up, but it's always a good idea to check the firing order when you get done. If your tractor starts and seems to idle OK, but does not want to pull a load, check the firing order.

The ignition system can be used to troubleshoot many problems. With the engine running, remove and replace each plug wire. Listen for a drop in RPM as a plug wire is removed. The plug wires I use do not have boots on the spark plugs, so it is a little less shocking to pull the end at the distributor cap. If you remove a plug wire without a corresponding drop in RPM, you have found a dead cylinder. If that is the case, it might be a fouled plug, bad plug wire, bad distributor cap, worn distributor, stuck valve, bad rings, burned piston, ... Bad wires are usually pretty obvious. It's hard to ignore the electro-shock therapy when you grab onto a bad one, or the light show you see with the engine running at night. If the problem only shows up when there is wet weather or high humidity, make sure your distributor cap and wire boots are in good shape. A little silicone grease on the boots can help keep moisture out and sparks in.

Check and see if your headlight switch works when the ignition switch is off. If so, yours is wired so that the headlight current does not go through the ignition switch. I believe this is the best way to do it. The ignition switch should last longer without the added load of the lights. The only down-side is you have to make sure both switches are off when you park it. But then, most people think being able to use the lights without turning the ignition on is an advantage. If you switch the ignition on just to use the lights (with the engine off) it can fry the coil.

CAUTION! The start pushbutton works even if the ignition key is off. This is normal. The start pushbutton grounds the wire from the start terminal on the solenoid. That is different from the way the automobile solenoids work. This means you can crank the engine even with the ignition turned off. Of course it won't fire until you turn the ignition on.

PLEASE, DO NOT replace the original ignition switch and start pushbutton with an automotive type ignition switch. This will bypass your neutral safety built into the pushbutton start switch. You may not think so, but many people have managed to get run over and even killed by one of those big rear tires.

SERVICE THE POINTS

People who owned a boat back when points ignition systems were common may be very aware of invisible deposits that can form on the ignition points. The combination of heat, humidity, electrical current, and a little oil can form deposits that will cause a set of points to fail. Modern replacement points are often using materials that are not as good as what was normal back in the good ole days. When one of my tractors fails to start right up, the points probably need attention. Ignore the problem and it will only get worse. There is absolutely no reason one of these tractors should be considered cold-natured or hard-starting. Grinding the starter more than a few seconds is just adding lots of wear and tear to the cranking system. On a front distributor engine remove and service the distributor. On a side distributor engine, remove the distributor cap, rotor, and dust cover, and look at the points. They should be clean and shiny. This may require pulling the movable arm away from the fixed contact if the points didn't stop open. Anything but clean and shiny is bad. Even if they look good, run a point file thru them a few times to make sure they are clean.

Pits and valleys on the surface of the points means the condenser is bad or the wrong rating. Badly pitted points should just be replaced. Using an ohmmeter, check for any resistance across the points. On a side mount distributor, take the distributor wire loose from the coil, bump engine till points are closed, and measure resistance to ground thru the distributor wire. Any resistance is bad. Look for and fix and corroded terminals, connections, copper strips.

Filing points. Some folks say filing points just makes them rough and more likely to have problems. Baloney. I've restored too many non-functional sets for that to be true. A good point file really isn't a file, it is a burnishing tool. Some versions may appear to be a very fine, thin, flexible file, with a chisel end. The chisel end makes it easy to slip between the points. Using just the normal spring tension with points closed, draw the tool back and forth between the points. A good burnishing tool does not aggressively remove material, it cleans and polishes. It is possible to restore a set of burned and pitted points if a new set is many miles away. In that case, a regular file can be used to remove pits and valleys, before cleaning and polishing with a burnishing tool.

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