Alternator Conversion Instructions – Print this page and follow along with Wiring Diagram and Illustration of a 1957 Chevy right inner fender. Disconnect the large cable from the positive battery post. There should also be a 12 gauge black wire connected at this point going back the battery terminal of the voltage regulator. Disconnect all three wires attached to the generator. There should be a 20 gauge dark blue connected to the field terminal and a 12 gauge black ground wire connected to the case of the generator. Plus 2 brown wires connected to the armature terminal. One is a 20 gauge brown wire that goes back to the dash connector plug and a 14 gauge brown wire that connects to the armature terminal on the voltage regulator. Remove bolts and upper brace on generator. Loosen 2 bolts and nuts attaching generator to the lower bracket. Push generator toward engine and remove belt. Remove the 2 bolts on the lower generator bracket and generator. Remove the lower generator bracket.
Disconnect a 14 gauge red wire on the battery terminal of the voltage regular going to the horn relay. Also on this terminal is a 12 gauge black wire coming from the battery. Disconnect and remove the 14 gauge brown wire from the armature terminal of the voltage regular. This wire will not be used again. Disconnect and remove the 20 gauge dark blue wire from the field terminal of the voltage regular. This wire will not be used again. Disconnect and remove the 20 gauge black wire from the voltage regular case. This wire will not be used again. Remove the voltage regulator mounting screws and voltage regulator. The regulator will not be used again.
Install your new or used lower alternator mounting bracket that fits your application. Mount the new alternator to this bracket. Install your new or used upper alternator mounting bracket. Install new Alternator belt, adjust tension and tighten all alternator mounting hardware.
The Wiring is quite simple and makes use of some old wires. We will start with these first. Plug in the 2 conductor GM alternator cable you purchased at your local auto parts store. Determine which wire is the Field connection and mark it (usually marked terminal 1 on rear of alternator). Do the same for terminal 2 which is the Voltage sensing wire.
Reconnecting the Alternator Field Terminal
Additional Alternator Conversion Instructions – Locate and inspect the 20 gauge brown wire you removed from the generator armature terminal. If this wire is damaged in any way, replace the damaged section with the same size and color. Connect this wire to the alternator field terminal pigtail wire.
New Equivalent Circuit
- Positive terminal of battery to key switch.
- Key switch to indicator (idiot) lamp.
- Indicator lamp to alternator field terminal.
- Alternator Field to Ground.
Reconnecting the Alternator Remote Voltage Sensing Terminal
Remove the short piece of 14 gauge red wire connected to “B” terminal of the Horn Relay. Connect a short piece of number 12 gauge black wire to the pigtail wire marked “2” at the alternator. Run this short piece of wire to the Horn Relay “B” terminal. Connect the number 12 gauge black wire coming from the positive battery terminal to the “B” terminal of the horn relay. This is your alternator remote voltage sensing wire.
New Equivalent Circuit
- Positive terminal of battery to “B” terminal on horn relay.
- “B” terminal of horn relay to alternator terminal number 2.
Reconnecting the Alternator Battery Charging Wire
From the large alternator “BAT” terminal connect a number 10-gauge wire to the positive post of the battery.
New Equivalent Circuit for Alternator Conversion Instructions
- Alternator battery terminal to battery positive.
Alternator Battery Chassis Grounding
Connect a number 10-gauge black wire at the ground location of your alternator to chassis ground. Make sure that there is a ground strap from your engine to the firewall and from engine to frame. Inspect and or replace the battery negative ground wire to chassis. Your generator to alternator conversion is now complete. Re-check your wiring to make sure it is correct.
Alternator Conversion Instructions