I'm sure this has probably been discussed before, but I did a search and didn't see it. I have a 71 with a 350. The car originaly had a 307. When I built the motor I put an HEI in it. Everything worked fine except that the starter would get heat soaked and not want to turn over. I decided to get a high output mini starter to fix this. The original starter had a connection for the battery cable, an S terminal, and an R terminal. The new starter has a terminal for the battery cable and a tab for the switch wire. One of the 2 (s-r) wires is black and heavy gauge, the other maybe 16 awg and purple. When the ignition switch is in the run position, the purple wire has 12 volts to it. The other wire does not have any voltage in the run position. Any help would be appreciated.

 

You can disconnect that purple wire from the coil, it's not needed with the HEI. That is a coil bypass wire for the old points & condenser distributor. The old ignition ran off a resister wire supplying about 10 volts to the coil. A full 12 volts would toast the points. But the drain of the starter would make the engine hard to start because of the coil not getting enough power. So, the bypass wire at the starter shot a full 12 volts to the coil only while the starter is cranking. Normally, that wire would read the resistance value in the run position, not a full 12 volts. Since yours is reading 12 volts means a new 12 volt source was run to the HEI. The other wire (s connection) should be reading 12 volts only when the key is in the start position, which is what activates the solenoid.