Car Won't Start While Cranking

Quick check to determine if there is power available in the ignition start circuit:
1. Remove a connector from the ballast resistor.
2. Connect a voltmeter probe to the connector with the ignition start wire (Brown & Blue for '68)
3. Turn key to start. Should show over 9.5 Volts and the engine should start (but will stop running when the key is released to run)

If it shows voltage but is weak, it could be battery or could be resistance.
Repeat the test but this time connect the meter's negative probe to the connector and its positive probe to the battery positive.
This will show voltage drop (resistance) in the feed circuit whic indicates poor connections somewhere in the flow path.