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MCHinson · 09-05-2010, 06:34 PM

Sounds like it could be an ignition circuit problem. There are other possibilities as well.

Here are the instructions for testing the ignition circuit from the technical tips section of the MAFCA website. Cut and paste is easier than typing. Hopefully this will help you find the problem.

http://www.mafca.com/tqa_electrical.html

Here is a voltage check of the circuit:
Connect the (+) side of your volt meter to a good ground point on the engine or frame.
Touch the (-) probe to the passenger side terminal box wing nut. Read 6 volts.
Touch the probe to the driver side terminal box wing nut. Read 6 volts.
Touch the probe to the (-) terminal on coil. Read 6 volts.
Touch the probe to the (+) terminal on coil. Read 6 volts.
Place a piece of paper between the point contacts.
NOW TURN IGNITION KEY ON.
Touch the probe to the end of the points arm, read 6 volts.
Remove paper between points. Open and close points and look for spark each time points open, (no spark means bad condenser, replace condenser).
If points are sparking then disconnect the coil center (high tension wire) from the distributor cap (leave connected at distributor end). Place the free end of the coil wire about 1/8" from one of the engine head nuts. Crank the engine over with the ignition key on. There should be a bright blue arc from the coil wire to the nut (ground point). No arc means bad coil.
Having said all of that, there are several things to check for. New condensers can go bad and new coils can go bad. But I would first look for something that may be shorting the circuit or causing an open in the circuit. Some of the other things to check are: Bad Ammeter. If ammeter has open circuit, all voltage is lost to the coil. You probably burned the wiring up because of loose connections on the back of the ammeter, or missing rubber grommet through center of terminal box, causing the ignition cable to short against terminal box posts, causing large current draw to burn wires. Do not screw ignition cable into the distributor too far. It can short out if screwed in too far. Make sure all nuts on the terminal box posts are tight. Also the two rivets on the bottom distributor plate sometimes get loose (especially on the reproduction plate) and short out the bracket it attaches. - Les Andrews, 1998 Technical Director

09-05-2010, 06:34 PM	#3
MCHinson Senior Member Join Date: Jul 2010 Location: Wilmington, NC Posts: 401	Re: how to test spark? Sounds like it could be an ignition circuit problem. There are other possibilities as well. Here are the instructions for testing the ignition circuit from the technical tips section of the MAFCA website. Cut and paste is easier than typing. Hopefully this will help you find the problem. http://www.mafca.com/tqa_electrical.html Here is a voltage check of the circuit: Connect the (+) side of your volt meter to a good ground point on the engine or frame. Touch the (-) probe to the passenger side terminal box wing nut. Read 6 volts. Touch the probe to the driver side terminal box wing nut. Read 6 volts. Touch the probe to the (-) terminal on coil. Read 6 volts. Touch the probe to the (+) terminal on coil. Read 6 volts. Place a piece of paper between the point contacts. NOW TURN IGNITION KEY ON. Touch the probe to the end of the points arm, read 6 volts. Remove paper between points. Open and close points and look for spark each time points open, (no spark means bad condenser, replace condenser). If points are sparking then disconnect the coil center (high tension wire) from the distributor cap (leave connected at distributor end). Place the free end of the coil wire about 1/8" from one of the engine head nuts. Crank the engine over with the ignition key on. There should be a bright blue arc from the coil wire to the nut (ground point). No arc means bad coil. Having said all of that, there are several things to check for. New condensers can go bad and new coils can go bad. But I would first look for something that may be shorting the circuit or causing an open in the circuit. Some of the other things to check are: Bad Ammeter. If ammeter has open circuit, all voltage is lost to the coil. You probably burned the wiring up because of loose connections on the back of the ammeter, or missing rubber grommet through center of terminal box, causing the ignition cable to short against terminal box posts, causing large current draw to burn wires. Do not screw ignition cable into the distributor too far. It can short out if screwed in too far. Make sure all nuts on the terminal box posts are tight. Also the two rivets on the bottom distributor plate sometimes get loose (especially on the reproduction plate) and short out the bracket it attaches. - Les Andrews, 1998 Technical Director