What are the AMP rating for my 72 Skylark?

Discussion in 'Small Block Tech' started by 72skylarkconvt, Aug 26, 2019.

  1. 72skylarkconvt

    72skylarkconvt Well-Known Member

    I have AC, 350 motor, what amp rating alt should I get for my car? It squeals some, may as well replace it while TC issue I am dealing with is fixed.
     
  2. alec296

    alec296 i need another buick

    I would think its more a belt issue.
    Should be around 62-75 amps.
     
  3. 72skylarkconvt

    72skylarkconvt Well-Known Member

    Belt issue? Squeal was the wrong word to use. It is a bearing going out type of noise coming from the Alt.
     
  4. alec296

    alec296 i need another buick

    Well bearing is a different issue. Might as well get new belt though
     
  5. 72skylarkconvt

    72skylarkconvt Well-Known Member

    yea i was going to have new belts put on when I have the TC cover replaced.
     
    alec296 likes this.
  6. GSX 554

    GSX 554 Gold Level Contributor

    Those years used either a 37 amp or a 55 amp alternator . The 55 is used with AC . If you look at the case where the adjusting bolt is it should be marked .
     
  7. 72skylarkconvt

    72skylarkconvt Well-Known Member

    ok thanks for the info.
     
  8. Schurkey

    Schurkey Silver Level contributor

    The obvious answer is to stuff in a dirt-cheap, ultra-common 10- or 12-SI internally-regulated alternator. If your car came with a low-amp internally-regulated alternator, the 55--60 amp alternator is a fine upgrade needing no other mods. I prefer a QUALITY rebuilt Delco alternator to the horde of crappy Communist knock-offs sold as "New".

    If you had the 10DN external-regulated alternator, the newer SI alternator will produce more output at idle even if peak output is about the same. You need a harness pigtail and two short jumper wires. "Even a cave-man could do it".

    There are still-newer alternator designs that can give you in excess of 100 amps and still-better output at idle...but you're unlikely to need them.
     
  9. 72skylarkconvt

    72skylarkconvt Well-Known Member

    I am keeping the car stock, no thumping tunes or anything that needs extra power. I just want a stock unit that the car has now.
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The internally regulated alternators are superior to the externally regulated units, especially at idle. GM started using them in 74 or so? It is fairly easy to convert the wiring. They look virtually the same.

    http://www.buickperformanceclub.com/alternat.htm
     
  11. Schurkey

    Schurkey Silver Level contributor

    Hell, yes.
    I thought the 10-SI was installed starting in '71 or '72, but American Autowire says they started in '69. I'm not sure I believe them. There was also a goofy short-production run of hybrids, external-regulated alternators inside internal-regulated alternator cases. I've never seen one in person.

    These folks also say the 10SI began in '69. What do I know?
    https://alternatorparts.com/how-to-identify-your-gm-alternator.html
     
  12. Schurkey

    Schurkey Silver Level contributor

    You'd be NUTS to keep an externally-regulated alternator when the 10- or 12SI is so easy to convert to, inexpensive, more reliable and more output at idle.

    But then, your vehicle may already have a 10SI alternator.

    [Edit] You know that the OEM alternator amperage output is stamped-into the alternator case, right? You want to know what you have, all you have to do is clean up the case a little, and read it from the case itself. [/Edit]
     
    Last edited: Aug 27, 2019
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I wasn't sure, I stand corrected.:)
     

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