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Chevy 250 Straight Six AC & PS Help Needed!!

Discussion in 'The Hokey Ass Message Board' started by jagvic, Mar 9, 2010.

  1. jagvic
    Joined: Feb 17, 2010
    Posts: 5

    jagvic
    Member

    Hey Guys,

    I'm trying to install AC on a 75 Chevy 250. The car originally started off with PS, so there were 2 groove pullies on the balancer and water pump which drove the alternator (groove closest to block) and PS (second groove away from block). I purchased some AC brackets and pullies and installed them with a compressor. The pullies were add ons for both the crank and water pump so that now each has3 grooves. I was told that in the original installation when you had AC that it was driven by the second goove away from the block, and that the PS belt is moved out to the third groove away from the block. Upong installing the AC I see that yes it aligns perfectly with the second groove. Then again, so does my PS pump pulley! So I need to somehow move the PS pulley further forward (away from the pump) and I already have a single groove, flat pulley. Do they make ps pumps with longer shafts, or was there a pulley that was an INVERTED bell (ie the groove is completely forward of the end of the pump shaft OR did they have different brackets to mount the pump in AC cars??? I am at a real loss what to do! Thanks for all the sage advice I know I'm gonna get from you guys!
     
  2. Why can't the same belt power them both?

    Only reason I can see is if the belts won't wrap the pulley enough (measured in degrees) that there would be insufficient traction and the belt would squeal, the power steering would not power steer, and the AC would not Kool!
     
  3. jagvic
    Joined: Feb 17, 2010
    Posts: 5

    jagvic
    Member

    Well i see what you are saying, and I thought that too but it would only have a partial wrap of the crank pulley and then up to the PS and AC pullies - both of which are higher than the fan pulley. I don't think that's enough wrap to do the job...
     
  4. Snarl
    Joined: Feb 16, 2007
    Posts: 1,640

    Snarl
    Member

    Not sure about what the factory did, but March Performance sells several different pulleys for the older style GM PS pump and they have some dimensions listed for them on their website. Take a look and see if that helps...

    Perhaps a double groove pulley on the pump and just use the front groove, assuming the rear groove is located the same as on a single groove pulley??
     
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  5. maniac
    Joined: Jul 11, 2005
    Posts: 539

    maniac
    Member


    On my small block I have only 2 belts, with A/C, power steering on 1 and an alternator and water pump on the other.
     
  6. David Chandler
    Joined: Jan 27, 2007
    Posts: 1,084

    David Chandler
    Member

    I've read somewhere that Chevy made a 3 groove balancer for them. Maybe that would be for AC set ups? I've never seen one with factory AC so I'm not sure how they did it. But certainly the figured it out.
    Good Luck!
     
  7. The three grove balancers were on 292 motors but I am not sure if they are still available at the dealer.
     
  8. jagvic
    Joined: Feb 17, 2010
    Posts: 5

    jagvic
    Member

    Well i got the factory AC add-on pulley for the balancer (which turns it into a 3 groove) and also the add-on for the water pump pulley - which turns that into a 3 groove also... But like I said that puts the PS belt a goove furtheraway from the block from where my pulley on the pump is....
     
  9. adriancyt
    Joined: Dec 15, 2009
    Posts: 11

    adriancyt
    Member

    Hi, I am installing ac to my pontiac and it came with a chevy 250. I have the same problem, but did some reserch and I will going to put it on the driver side. I will post pic later, good luck

    [​IMG]

    [​IMG]
     
    Last edited: Dec 27, 2010
  10. lowmaster
    Joined: Oct 26, 2003
    Posts: 347

    lowmaster
    Member

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