Classic/Antique Car Repair: 67 mustang, starter relay, resistor

Question
I am restoring a 67 mustang the car was hot wired to the coil i replaced this, starter relay and resisotr wire the car starts but only runs if I hold the key in the start position.  Is it a problem at the key ignition or another idea?

Answer
It could be the ignition switch or some one some time has fooled with the wires on the back of the switch. What you will need to do is to make sure that there is voltage to the ignition coil when the key is in the run position. One side of the resistor should go to the plus terminal of the coil and the other end to the ignition switch. The ignition wire from the back of the ignition switch should be red with a green stripe. Check for voltage there. If there is voltage then the ignition switch is OK. 3.If no voltage make sure that there is voltage going to the switch. If there is voltage at the back of the switch then check at the resistor, To make sure that you get a good reading remove the wires for the POS + side of the coil and there should be voltage at both ends of the resistor. If not there is a break in the wiring between the switch and  the resistor wire. If all this checks out reinstall the wires at the POS side of the coil and remove the wire from the NEG- side of the coil. Now turn on the key and see if there is voltage at the POS side of the coil. If there is no voltage then there is a break in the wire from the resistor. If there is voltage the car should run.