Alternator Wiring Confused

If you intend to tap into a wire rather than repairing the original wiring "all the way back the way it's supposed to be, you'll want to find the wire that goes into the ballast resistor -- the one that shows ~battery voltage when the key is in the "run" position with both wires pulled off the ballast. Then tap into this wire in a good and durable manner (I recommend using a Posi-Tap). However, tapping into a wire really isn't a very good idea; you'll be throwing an extra 2½ amp load on the wire meant to feed the coil, which will overload that wire and tend to lower the voltage the coil sees, reducing ignition system performance.

You may want to take this opportunity to upgrade to the charging system wiring setup Chrysler used on heavy-duty applications, with a field load relay. This is very easy to do: fetch a good quality, name-brand (Tyco, Bosch, Omron, Potter-Brumsfeld) 12v "NO" relay with four terminals: 30, 85, 86, and 87. You'll also need a relay mounting bracket and appropriate terminals. Shouldn't be too hard or costly to come up with this stuff locally; in my store, relay + bracket/terminal block + terminals = $13. Go ahead and tap into the wire described in the first paragraph of this post with a Posi-Tap, and connect to relay terminal 86. Run a new wire (with a 7.5A fuse in it, if you're smart) to relay terminal 30 from the alternator B+ output stud or the big stud on the starter or anywhere else reasonably accessible on the main charge line that connects alternator B+ to battery poz. Connect relay terminal 85 to ground. Connect relay terminal 87 to the voltage regulator's "IGN" terminal. Connect the regulator's "FLD" terminal to the alternator's field terminal.

The field load relay brings the alternator and regulator electrically "closer" to each other and, more to the point of this post, relieves the overload condition described above.

While you are in there working on it, run a new 12ga ground wire from the alternator housing (sometimes there's a "GRD" hole you can put a short self-tapping screw into) to the regulator base and from the regulator base to the battery negative terminal; this will bring the whole system to the same ground plane and smooth-out voltage regulation considerably.

You may want to go download the wiring diagrams for your '63 before you get started.