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My 1976 Nova SS NovaResource
SI to CS Alternator Conversion
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photo 1: External to internal regulated alternator conversion photo 2: Charging Circuit photo 3: Front photo 4: Side photo 5: Back photo 6: Top photo 7: SI Front photo 8: CS Front photo 9: SI Side photo 10: CS Side photo 11: Alternator Bracket


In 1986 GM introduced the completely new, 105-amp, CS130 Delcotron alternator (CS130 = Charging System with 130mm diameter stator) because the SI alternators could not keep up with the increased electrical demand and because overdrive transmissions were lowering engine and alternator rpms. The CS130 weighs less, is smaller in diameter (but uses the same 6.6" mounting-hole, center-to-center distance photo 3), uses less internal parts, has a better voltage regulator system, has increased durability and is less noisy (audibly and electrically) than the SI alternator it replaced. There is also a 120-amp, CS144 version if you need more output because you're running large amounts of electrical equipment in your vehicle such as high-powered stereos.
NOTE: This conversion is designed for cars with internally regulated alternators. If your car has an externally regulated alternator you will need to convert it first. Use this diagram and go to Alex Bilan's Alternator Conversion webpage for more information on converting to an internally regulated alternator.
You will need 105-amp CS130 alternator from and late-80's GM truck or full size car with mounting ears that are 180-deg apart (photo 3). I got mine from the local PepBoys and it didn't take too long to find one with the correct mounting ears. I paid about $100 for new one with a lifetime warranty. Most will probably come with a pulley for a serpentine belt (like mine did) so you will have to change over your pulley if you are still using a V-belt.

The flange for the tensioning bolt and the alternator bracket are tapped for metric bolts so you will need to get two 8mm bolts with a thread pitch of 1.25mm. A 13mm wrench will be needed to tighten the bolts. The alternator bracket will also need to be modified and you will need approx two washers to take up the space between the alternator bracket and the alternator. Photo 11 shows the modifications needed to allow the bracket to fit the CS alternator. The red line shows the original shape of the bracket and how much needs to be ground away.

Most of the connectors for the CS alternators are four wire but will only use two of them and the wiring is the same as the SI.
  • S = a heavy gauge wire to the battery supply (horn relay)
  • F = not used
  • L = a small gauge wire that comes from the idiot light and energizes the alternator
  • P = not used
You need to purchase a conversion adapter that is just 2 short wires and 2 connectors. One is a CS connector to plug into the alternator, the other is a female connector to accept the SI plug from your original harness. There are two different types of conversion adapters. One is a non-resistor and the other has some resistance built-in it. The "L" wire that energizes the alternator needs some resistance (35 ohms or more) in it otherwise it will cause the alternator to fail. If you have a warning light in the dash then that bulb serves as the needed resistance and you should use the non-resistor adapter. If you don't have that bulb or have less than 35 ohms resistance in the "L" wire then you will need the adapter with resistance built in. If the "L" wire has more than 350 ohms then there is a problem with that wire and it will need to be fixed.

Non-resistor adapters:
- AC Delco: 8077
- Haywire: 2110
- Painless Wiring: 30707
Resistor adapters:
- AC Delco: 8078

Steps:
  1. Turn key to run position verify charging system warning light comes on
  2. Remove negative battery cable
  3. Disconnect the 2-wire plug from the side of the SI alternator
  4. Disconnect the heavy battery wire from the BATT terminal on the back of the SI alternator
  5. Remove belt
  6. Remove SI alternator
  7. Install pulley from SI alternator to CS alternator
  8. Remove alternator mounting bracket from SI alternator
  9. Modify alternator mounting bracket (photo 11)
  10. Install alternator mounting bracket and 2 washers to the CS alternator
  11. Measure the resistance in the "L" wire
  12. Connect CS wiring adapter to the CS alternator
  13. Connect the heavy battery wire to the BATT terminal on the back of the CS alternator
  14. Connect the wiring adapter to the original SI connector
  15. Mount the CS alternator to the engine
  16. Install belt and tighten
  17. Check all of your connections
  18. Make sure alternator output terminal is not shorting to ground
  19. Connect the negative battery cable
  20. If you don't have an installed voltmeter, connect a voltmeter to the battery terminals
  21. Start the car
  22. The charging system warning light should go out and there should be 14v at the battery. If there is not, check all connections
NOTE: the alternator supply line that connects to the BATT post on the back of the alternator is usually a 10- or 12-gauge wire. For a CS conversion, I suggest using at least an 8-ga charge wire.

Main Page Copyright 2001 Scott Windle Created on: 03/24/01