'49 8N Ignition Problem

Any Ideas on what I can look at next? And what should be the voltage at the coil on a 12 volt system with a 12 volt coil?

Thanks

Ken

P.s. I have looked at the archives, but there were 1650 hits when I looked for "ingintion".

If it is an Internal Ballast coil, then you will/should have 12v at the BAT side of the coil directly from the keyswitch all the time the switch is on. The internal resistor inside the coil will automatically reduce the voltage to the coil windings sometime after you start your engine. (It's a thermal thing, you supply power, it heats up & changes resistance, hence current to the coil.)

If you have a coil marked External Ballast, you MUST have a ballast resistor wired in series from the keyswitch to the BAT connector on the coil. If you do not have the ballast resistor in series with the 12v from the keyswitch, you will fry the new coil in a matter of several minutes. Some have successfully used the resistor behind the tractor dash as a ballast resistor for coils marked External Ballast.

Be sure to check the wiring between the points and the distributor. Install the dist, and connect your voltmeter to the Points side of the coil. Rotate the dist by hand (or bump the starter) to get the points open. The voltage at the connector should be around 12v (6-12v is fine). Now rotate the dist so the points are closed. The same connector should read 0v. Anything else and the points or wiring are suspect.

By the way, grasp the dist shaft and try to rotate it. If it rotates freely, the distributor drive gear is broken. (But then you already checked for that, didn't you?)

When you are checking for spark, remove the spark cable from the central tower of the dist cap. Hold it with something insulated (plastic pliers, etc) and place the free end in close proximity of the engine block (1/8" or so). Keep it away from the fuel line. Crank the engine with the key on. A good spark verifies the coil. Reinstall the coil lead in the dist cap.

Now remove one of the spark plug wires from the dist cap. Insert a spring-clip lead in the hole in the cap, and holding the free end of the jumper with something insulated close to the engine block, crank the engine as before. A good spark here verifies the rotor.

Now hold the same lead close to the spark plug. No spark here means the plug is not firing. It may be gapped wrong, the spark may not be hot enough, who knows. Reinstall the plug wiring into the dist cap.

Remove the spark plug, reattach its wire from the cap. Rest the side of the plug against the engine (good ground) and crank the engine with the key on. This will test the plug.

Hope this helps. Let us know the results.
Don8NAZ

Some of the information doesn't apply, as this
is a early 8n with the front mount distributor.
The coil is a 12 volt replacement for the 6 volt
coil that was on it. I had a dropping resistor in
line that I removed. After trying out the new coil
and getting no spark at all, (checking at a spark
plug wire) I took the "new Coil off" and found the
primary side spring terminal broken and shorting against the case. I will try to repair it using the terminal from the old coil and see what happens or I have to get another.

Thanks for the information.

Ken

And to answer your questions, yes it is a Front mount Distributor, and yes I had turned the gas
on. I checked the spark by takeing off the wires
and putting a screw driver in it and holding the shaft about a 1/16 of an inch from the top of the
sparkplug.

Thanks for the reply, When you said 8 volts with the points closed and 12 volts with them open, where should the voltage reading be taken?
The only voltage measurement I took was at the top
of the coil.

I am pretty sure they are opening and closing, at least they were on the bench.

Thanks,

Ken T.