can't get plugs to spark

[Jtrux]

Okay so let's clear this up. You get spark at the points?? I'm not too sure what you're talking about there.

First to check the coil, take the wire that goes from the primary tower of the coil to the center of the distributor cap and hold it near a ground source (block or firewall, probably block since firewall will be painted not allowing a good circuit ) and have someone turn it over, if coil is good you will see spark, no sparky, coil is bad.

If you're getting spark there but nothing at the plug there could be several things wrong. First what are your points gapped at?? 15 minimum and 19 if you have a high voltage coil. Actually let me correct myself you will need to adjust the dwell, IIRC you want anywhere from 32 to 36 degrees of dwell. If you have a stock coil you can keep it lower if you have a higher voltage coil you want it to be higher. Stock coil is around 40K and aftermarket is up to 50K or so.

Quick explanation...The wire going into the positive side of the coil should be roughly 6 to 9 volts. When the points are closed the voltage is entering the coil and making it's way though the primary windings of the coil increaing voltage by several hundred volts, when the points open a magnetic field that was containing the voltage to the primary windings drops and voltage jumps to the secondary windings of the coil increasing to many thousands of volts and then exits through the primary tower and makes it's way to the dizzy, then to the plug. The higher the dwell number the longer the time the coil has to produce maximum voltage. If you have a high voltage coil with low dwell then you're shorting yourself on voltage and the same goes if you have a low voltage coil with a high dwell, the coil will reach maximum voltage then drop off, so you are still shorting yourself. There's a little science involved with it.

So if you still don't get spark i'd be willing to bet money that it's your capacitor.

Oh and as far as the stock wiring goes, there is probably a wire coming from your starter to the coil. The reason it's there is because when you're cranking the engine over the starter is sucking up all the juice so the resitor wire that's only allowing 6-9 volts to the coil is probably getting half that so inorder to help with starting a wire goes from the starter (12 volts) to the + only during start up to help during initial start up since the starter uses so much power. Then when you motor fires up and the starter is disengaged your coil gets its power from the resistor wire.

Hope this all makes sense.