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Alternator Upgrade

Discussion in 'The Hokey Ass Message Board' started by 64impala, Dec 18, 2012.

  1. 64impala
    Joined: Sep 14, 2012
    Posts: 79


    I'm planning on upgrading my original 55 amp external alternator to a 100 amp internal, this will help carry the additional amp load for my spal fan, digital dash, stereo, etc. on my 1964 Impala (327 cui) with HEI upgrade!
    I plan to use a 3-wire conversion kit:

    Few Questions:
    What year "internal" alternator" should I consider upgrading to? I don't want to make any modifications on the mounting (bolts), etc.
    Example: Could I purchase an 85 Camaro "internal" alternator and bold it right up without modifications?

    What do the numbers represent in "12SI" alternator term versus 10SI, is that just a model number?

    Will I be required to remove my stock voltage regulator or can it remain in the original configuration regardless of the internal alt upgrade?
  2. You must wire around the voltage regulator. If you want to leave looking like it works just terminate the wire inside your harness and wire in the new one. The 85 will bolt up but be sure you leave the regulator out of the new wire loop. I have a schimatic (sp) I think I could scan for you.

  4. 64impala
    Joined: Sep 14, 2012
    Posts: 79


    If I'm converting from a 12 o'clock external alternator to a 12SI, does it make a difference what clock position the 12SI sits?

    Joined: Aug 7, 2009
    Posts: 2,069


    When you disconnect the 64 voltage regulator, connect the brown & red wires together on that regulator connection.

    Th alt should look like this

    Attached Files:

  6. CodeMonkey
    Joined: Sep 13, 2012
    Posts: 93

    from Moline IL

    Clock position has nothing to do with how the alternator functions, only how easy it is to connect/disconnect the wiring. There's only 4 bolts that hold the front to the back; after they are removed, with a little wrangling you can re-clock it to suit your needs. You just need to be careful that the stator (looks like steel plates sandwiched together between the two halves of the housing) rotate with the back housing. That's where it's connected, and it's only connected by the wires that connect the stator to the rectifier.
  7. brokenspoke
    Joined: Jul 26, 2005
    Posts: 2,947


  8. B.A.KING
    Joined: Apr 6, 2005
    Posts: 4,032


    just a note. i bought a kit from to change over from generator to alt. I HATE WIRING, scared,say scared,scared of wiring.anyway. great product, and i pestered this guy to death with questions. always had time for me,very smart guy. super nice.answered all my ????? . can't say enough good about him and his product jmho.................... that you didn't ask for, sorry!
  9. 64impala
    Joined: Sep 14, 2012
    Posts: 79


    One more question, I presume I will also be eliminating my horn relay (I don't use my stock horns, so the horns were disconnected, but the wiring is still connected to the horn relay).

    If so, would I just run the hot wire from the internal alternator straight to the battery and bypassing both the external voltage regulator and horn relay?

    Thanks again!
  10. Jack E/NJ
    Joined: Mar 5, 2011
    Posts: 728

    Jack E/NJ
    from NJ

    If you don't mind a chrome alternator, get this new, no-core-needed 110-amp 10-SI clone for $80 As with all SI-series, it can be run as a 1-wire, 2-wire or 3-wire setup.
    For a 1-wire, run a pigtail wire from the #2 sensor terminal directly to the battery output terminal. The #1 exciter terminal is left open. Without the exciter terminal connected, you sometimes must rev the engine a bit to get it to start charging from residual magnetism in the alternator as mentioned.
    For a 2-wire setup, again run a pigtail from #2 to the battery output terminal. The #1 terminal is then connected to the ignition switch thru a bulb and/or resistor in series as mentioned above.
    For a 3-wire setup, run a wire from #2 to some remote circuit location to sense voltage at that point. The #1 terminal is connected like the 2-wire setup. The 3-wire is allegedly the best setup to keep battery properly charged or so it's claimed.

    Jack E/NJ
  11. 64impala
    Joined: Sep 14, 2012
    Posts: 79


    Researching a 12SI Delco Remy 94 amp alternator to replace my stock external setup. Still researching the amps during "idle", waiting for
    Delco Remy reply.

    What would be a decent amperage reading for the "idle speed" on this type of alternator?

    I'm running a dakota digital dash, modern stereo, hei, and spal 60amp fan!

    Thanks for all the previous great info and resources!

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