[67 chevelle]

purple is the standard color wire that goes to your neutral safety switch and from there another purple wire goes to the starter selinoid

if you are running a point type ignition , as bigdave160 said the yellow attaches to the positive side of the coil for full 12 volt suply only while cranking , the other white wire that attaches to the positive side of the coil is a resistor wire that usually measures at 9 volts in the key on position