Alternator 12 SI upgrade

Discussion in 'Small Block Tech' started by Double6skylark, Mar 5, 2019.

  1. Double6skylark

    Double6skylark Well-Known Member

    I'm looking at upgrading my alternator to a 100 amp 12 SI because I want to run electric fans on my radiator,
    anyone done this? Also looking to go with an aluminum radiator / electric fan combo in place of the stock unit, anybody have any recommendations? I've also gonewith an HEI distributor, any recommendations on HEI engine wiring upgrade?
  2. 12lives

    12lives Engage! - Jean-Luc Picard

    Double6skylark likes this.
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I have a 12SI with a 94 Amp rating. Use the instructions below,

    I recommend you go with just the aluminum radiator. No more than 2 rows of tubes. Tube size AT LEAST 1", 1 1/4" is better. If you see any aluminum radiators with more than 2 rows, don't waste your money. The stock clutch fan and shroud, along with a Griffin 2 row 1 1/4" tubes keeps my 602 HP 470 below 185* at all times. Electric fans are unnecessary IMHO.

    HEI needs full time battery voltage. Do it right, remove the resistance wire and replace it with a 12 gauge wire. See the thread below,
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  4. alec296

    alec296 i need another buick

  5. 1987Regal

    1987Regal Well-Known Member

    I agree on 2 row with 1 inch wide tubes each or 1 1/4. I bought the 3/4 wide 2 row from champion and my regal with ac would not stay cool at highway speeds. Switched to 1" 2 row took care of my problems
    Double6skylark likes this.
  6. Double6skylark

    Double6skylark Well-Known Member

    Thanks @LARRY70GS I really appreciate your experience and insight. Much appreciated

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