[awesomepossm]

You have already got good advice on things to check for "No spark" However, it will help to focus the search for the cause on the right part of the ignition system. You do this by dividing the system up into subsystems and testing each subsystem. Start with the coil.

The coil is a transformer. It has a primary winding and a secondary winding. The secondary winding supplies the spark. This spark occurs when the current through the primary winding is interrupted when the contacts open. To test the coil:
Check the voltage supply to the coil. Disconnect the wire supplying voltage to the + term on the coil. Dont be confused by other wires that might be connect to the coil. Normally, there should be a wire from the ignition switch directly to the coil. This is the wire you want to locate. Sometimes, this same wire will supply voltage to the voltage regulator on the alternator. If so, there will be another wire from the + term of the coil to the regulator. The ignition switch might supply the voltage regulator first and then the coil in which case there should only be one wire connected tot he + terminal of the coil. Other wires connected to the coil might supply an RPM meter or an electric fuel pump so it can be confusing. I hope this info helps you sort out the correct wire.

Use a 12 V test light to put a load on the coil voltage supply. Hook the light between the wire and engine. Turn on the ignition. Use a volt meter to measure the voltage across the light. It should be 12 VDC.

You need the test light to put a load on the voltage supply to the coil to make sure you do not have a bad electrical connection between the battery and the coil. Without a load you can measure 12 vdc even with a bad connection. High impedance volt meters draw such a small current that a bad connection is easy to miss.

If you have good voltage to the coil, check continuity of the primary circut for the coil. To do this the points must be closed. Remove the distributor cap and inspect the points. If necessary, bump the starter until the points
are closed. Hook the test light up between the voltage supply to the coil and the + term on the coil. Turn on the ignition and the light should be lit brightly.

Test the coil secondary winding. Hold the end of the ignition wire from the coil to the distributor cap near the engine head. Use a screw driver to pry open the points. When the points open you should get a spark and the test light will go out. You have to have a good ground between the engine block and coil housing to get a good spark. This is part of the secondary circuit. Make sure that paint on the engine block, coil bracket or coil housing is not interupting the secondary circuit.

If you got a good spark, the problem is in the distributor system. e.g. crack in the distributor cap, bad ignition wires, damaged spark plug, bad rotor, etc. If you didnt get a spark, make sure the condenser/capacitor is not shorted. When the points are open, the test light should go out. If it stays lit, continuity in the primary circuit is maintained by a short in the condenser. If this occurs, disconnect the condenser form the points and test the coil again. If you get a spark, the coil is good. Dont worry about the coil yet if you didnt. The condenser helps prevent burning of the points The condenser is also part of the primary LRC circuit and in theory is matched to the coils resistance and inductance. Replace the condenser and test the coil again. If still no spark, replace the coil.

The fact that you get a spark when you turn the iginition on and off tells me that the problem is a short in the primary circuit. HOpe this helps