Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Who makes under/over-drive pulleys/dumb Powermaster alt

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by CaptCrunch, Aug 29, 2001.

  1. CaptCrunch

    CaptCrunch 1/2 ton status

    Joined:
    Feb 2, 2001
    Posts:
    3,596
    Likes Received:
    1
    Location:
    Minnesota
    Here is my boggle. After some diagnoisis I have found my Powermaster alternator isn't putting out enough juice at idle. This is because dumb Powermaster sent me an 140amp alt w/ a V style pully on it. I called and asked what the deal was because I have the serp style pulley. They said switch the pulleys and it would be fine. Well I definetly wasn't convinced because you can see that the V belt pulley is about half the diameter if that of the serp style pulley, so now I'm stuck either finding a smaller style serp pulley or going to the junkyard to find the crank and water pump pulleys off a V-belt truck. Not a major deal, but a PIA. So to the point... who makes over and under drive pulleys beside March? I tried them and they don't make an overdriven pulley.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  2. 502Burban

    502Burban 1/2 ton status

    Joined:
    Jun 8, 2001
    Posts:
    379
    Likes Received:
    0
    Location:
    Southern California
    Hey Mikey,

    This doesn't necessarily answer your question, but _may_ be an answer to your problem. Have a friend with a Powermaster alt who was experiencing the low output at idle that you describe. Turned out that since he had the one-wire alternator, he needed to blip the throttle after startup to activate the alt. Seems that one-wire units need to reach a certain rpm B4 they start to charge. You are probably already aware of this, but thought I'd mention it just in case.

    Another thought: the serpentine pulley may be bigger in diameter due to different routing that would overdrive the alt too much if used with the smaller diameter v-belt pulley.

    Sorry if this isn't any help.

    Robb
    '73 GMC Suburban - 502DFI
    <a target="_blank" href=http://community.webshots.com/user/robbrj>community.webshots.com/user/robbrj</a>
     
  3. CaptCrunch

    CaptCrunch 1/2 ton status

    Joined:
    Feb 2, 2001
    Posts:
    3,596
    Likes Received:
    1
    Location:
    Minnesota
    I guess I will give it a try... but you would think that once you got going down the road it would have reache whatever rpm. What rpm did it start at? Mine doesn't have a problem charging in park... just when it is in gear and the rpms drop to 600 rpm... if I shift to N it improves a little (700 rpm). But hey it is an easy thing to try [​IMG]

    This is the kinda half serp belt setup as I say. You still tighten the alt like on a V-belt truck, it is just the belt is a smaller serp belt style for some reason. Thanks for the input... anyone else??

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  4. 502Burban

    502Burban 1/2 ton status

    Joined:
    Jun 8, 2001
    Posts:
    379
    Likes Received:
    0
    Location:
    Southern California
    I have a couple of articles that address the one-wire alt's need to acheive a certain rpm before starting to charge; I think they were Chevy Hi-Performance. I'll have to look for them later, but they did actually discuss what rpm was needed.

    In the meantime, here is a link to a page on Powermaster's site that discusses pulley diameters and how to size them properly: community.webshots.com/user/robbrj
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

    Joined:
    Feb 2, 2001
    Posts:
    3,596
    Likes Received:
    1
    Location:
    Minnesota
    I subscribe to CHP so I'll have to take a look. The pulleys are stock, but the alt's are tested with the V belt pulley on so if that is half the size of the serp pulley then the alt is only going half as fast at idle, which is where I need it. Reading the article it really makes me wonder why the heck Powermaster told me to change the pulleys. DUMB!

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  6. '73 K5

    '73 K5 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,763
    Likes Received:
    0
    Location:
    Kansas
    Thats weird brotherman. Hopefully you can get the pulley thing taken care of. I'm super happy with my Powermaster 140. I have mine still hooked up 3 wire though. Anyways with a lopey 700 RPM idle I can turn on both of my ProComp130 lights and the voltmeter barely moves.

    '73 K5
    Chevy good...Ford bad
     
  7. BIGRIG

    BIGRIG 1/2 ton status

    Joined:
    Feb 29, 2000
    Posts:
    488
    Likes Received:
    0
    Location:
    Independence, MO
    I used to work in a parts store and 99.9% of all pulleys are the same for f@rds, Chevys, dodges and so on, go to the junk yard and find any pulley with the same # of ribs yank it off (don't give the guy more than a couple dollars for it) and make sure it is the size you need and that the inner diameter is the same for the shaft. to make sure of this take the old V-belt pulley with you to measure with. hope this helps.

    Chris C.


    MY DRINKING TEAM HAS A FOUR WHEELING PROBLEM![​IMG]
     
  8. CaptCrunch

    CaptCrunch 1/2 ton status

    Joined:
    Feb 2, 2001
    Posts:
    3,596
    Likes Received:
    1
    Location:
    Minnesota
    Yeah... well I can't go my my alt guage cause it is messed up.... heck you turn on a blinker and thing go nuts so either guage wiring is messed or the guage is bad. I just wish I tested the stupid alt output earlier... I figured since H ad failures a couple of times on the driver's side tail/brake lights it was a busted wire so I rewired the entire back half of the truck. Well my own fault for trusting a new Powermaster alt and their tech guy. I see Wrangler has some overdriven pulleys or I will just get the V belt setup on the alt and pickup the water pump and crank pulleys. Then I hope to heck it is all fine.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     

Share This Page