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charging Q & A TIME ?????

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bklynlifted, Jul 4, 2002.

  1. bklynlifted

    bklynlifted 1/2 ton status

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    ok this is what's going on went to the zone and got a 94 amp alt, rebuilt of course $64.00 so i do the install and with my light's , ac, and sond system on the car up to temp my gauge is reading at below 13v went right to the alt and i'm at 12.64 the same as the old alt?? at the battery im getting 12.58?? my idle is down to 500 to 550 rpm's whats the deal idle to low and maybe swap in a yellow top optima??? /forums/images/icons/confused.gif
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Idle's too low. Stock alternators don't put out enough at low RPM's. 700 or 750RPM's will likely take care of the problem. But you are still over 12 volts, and I would be surprised if once you didn't hit 700 or so RPM's, the output was back up to 13 or more. If it is, don't worry about it.

    I'm in the process of trying to find some "overdrive" pulleys that we can use, if it would bump alt speed up just slightly, we could still run low idle RPM's, but keep the alternator spinning fast enough to keep the lights from dimming.
     
  3. trailblazer87

    trailblazer87 1/2 ton status

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    Yeah sounds like its just a little low on the speed. Get a smaller pulley and it will bring the alternator speed up to where its output should be.
     
  4. reddog64

    reddog64 1/2 ton status

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    yup what dorian said is my thoughts...

    Let me know if you find that pully, i'll buy one
     
  5. bklynlifted

    bklynlifted 1/2 ton status

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    thanks for the reply's i thought the idle was too low should be bumped up to 700-750 next question how do you raise the idle on a 350 tbi ??? who has a smaller pulley i can buy or just start looking in the bone yards . ive got the serpintene belt. thanks guys /forums/images/icons/wink.gif
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Ok well thats just not fair lol. Us with v-belts don't have this option: http://www.alternatorparts.com/pulley_size.htm

    I've never dealt with them, but its where I heard about "overdrive" pulleys. Not even sure how many grooves the C/K serpentine setup has. Probably those six though : )

    Just don't forget, (for example) if you went from a 3" to 2" pulley, you increase the alternator speed by 33%, and since its already "overdriven" from the motor because the crank pulley is larger, you will have to be careful not to get crazy with overdriving it...you increase wear on the alternator, and apparently at ultra high RPM's, they can or will self destruct.

    I thought TBI idle speed could be adjusted at the throttle linkage on the TBI itself, but not positive.
     
  7. bklynlifted

    bklynlifted 1/2 ton status

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    thanks for the info dorian i'll head out today and start looking for the pulley and check the linkage, i don't think i rev higher than 3500 i drive pretty mellow. keep yall posted . thanks jack. /forums/images/icons/smile.gif web page
     
  8. bklynlifted

    bklynlifted 1/2 ton status

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    well i went out to the truck and counted the grooves 4 in my 88 jimmy sbc, as far as raising the idle every place i turn including under hood sticker says the idle cannot be adjusted it is controlled by the computer, so i ordered the 2 inch 4 groove pulley from alternatorparts.com 18.00 dollars delivered to the house. ill put up a new post after i swap it in if i can figure out hot to get the pulley off there a pain in the A$$. later guys. /forums/images/icons/smirk.gif
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Went out yesterday and measured 5 of the Delco alternators, all but one were 2 1/2 or 2 5/8, and the one hold out was 3". Hoping that compnay gets back to me on my request!
     
  10. bklynlifted

    bklynlifted 1/2 ton status

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    i think the 2 inch i ordered should take care of all my charging issues at low rpm in gear with all the accessories? i'll keep you posted there site didnot let me know what the shipping time would be?? /forums/images/icons/confused.gif web page web page
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah I'm curious to see what kind of difference you net. I'm sure it will be like night and day!
     
  12. 79Beast

    79Beast 1/2 ton status

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    I don't think you will "over rev" your alternator. Unless you are running a really wild motor, you just won't turn enough rpms. You should leave the idle where it is as long as the engine seems happy. Try going to a shop where they build starters and alternators. They should be able to get you a smaller pulley.......but don't be surprised if they look at you funny for buying the Autozone reman unit.
     
  13. bklynlifted

    bklynlifted 1/2 ton status

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    just ordered a 2 inch 4 groove pulley, it should be here in a few days i think it will boost my low idle alt output by about 25 to 30 pct ???with the ac sound system,headlights on in drive my idle goes down to 500 to 550 rpm to low. this pulley should do the trick, the truck runs great at this rpm, no missing, rought idle, sweet n smooth . keep ya all posted. /forums/images/icons/wink.gif
     

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