Allis Chalmers CA

[FtInn Farmer]

I have an AC CA that uses a magneto. When I go to hook up the battery ground cable I get a spark. It happens with the first contact of the cable. Is that normal or is there an electrical issue somewhere?

 

[Gene Davis (Ga.)]

With a magneto there is no battery draw for ignition. Sounds like something is causing a drain. Are your lights on?
Check for voltage regulator or cutout sticking and trying to energize the generator. If so the generator may feel
warm. Also sometimes old wires develop a slight ground through brittle or missing insulation. You probably need to
start tracing one circuit at a time to find it. Hook a test light to the ground post on the battery with the cable
off and touch the probe of the test light to each circuit one wire at a time till the light comes on and that will
most likely be the source of your ground(s).

 

[old]

Is it still 6 volts or is it change to 12 volts?? If 6 volts good chance the V.R. is going bad and the points are sticking. If 12 volts good chance the alternator has a short in it.

Also tell us any changes you may have done to the electrical system. Have you maybe rewire it or some other such thing or has this just started to happen

 

[Aaron SEIA]

Has someone farmer enginneered a mag into a distributor? You sure it's even a mag? There should be zero power ever to or from a mag outside of when it fires.
AaronSEIA

 

[FtInn Farmer]

(quoted from post at 07:37:50 11/18/19) With a magneto there is no battery draw for ignition. Sounds like something is causing a drain. Are your lights on?
Check for voltage regulator or cutout sticking and trying to energize the generator. If so the generator may feel
warm. Also sometimes old wires develop a slight ground through brittle or missing insulation. You probably need to
start tracing one circuit at a time to find it. Hook a test light to the ground post on the battery with the cable
off and touch the probe of the test light to each circuit one wire at a time till the light comes on and that will
most likely be the source of your ground(s).

The only item hooked up on the tractor is the magneto. At present, there are no other electrical items on the tractor including an on/off switch. I am presently redoing the tractor. I just wanted to make sure it will run before going further.

Thank you for your help.

 

[Jim.ME]

Please explain "The only item hooked up on the tractor is the magneto." How is it hooked up? Other than spark plug wires, the only other wire I can think of that might go to a magneto is a ground wire which could have been run to a switch. That wire would ground the mag out to stop the engine. Some mags only had a spring tab on that stud the operator pushed against the mag housing to ground out the mag. If it has a wire to a stud on the side of the mag remove the wire and see if the sparking stopped when hooking up the battery cable. (Checking with a voltmeter would be a better check.)

 

[Aaron SEIA]

Does it have a generator on it? Try pulling the wires off of that. It could be shorted out. Light switch in the instrument box? Make sure no wires are grounded. Shouldn't be sparks from anything when hooking up the batteries.
AaronSEIA

 

[dahlin]

could your starter cable be shorting out some where. Randy