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Vacumm Advance 81 K5

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Trailblzn, Nov 5, 2003.

  1. Trailblzn

    Trailblzn Registered Member

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    I am getting conflicting info on wether or not my truck should have vacumm to the distributor at idle or not. I changed the vacumm switch on the thermostat housing and now the vacumm advance has no vacumm at idle. Any ideas. The motor runs rough just off idle.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Most trucks were set up with no vacuum at idle. Not all, but most. I would *speculate* all K5's your vintage were, based on the emissions class.

    All you did was change the switch? Are you sure you got the right one?
     
  3. Trailblzn

    Trailblzn Registered Member

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    Yes the part number matches the old switch, I'm not sure why it runs rough just off idle.
     
  4. R72K5

    R72K5 Banned

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    well, it depends, theres no solid answer, it really depends on how it runs with it either connected to full, or to part time, i alays connect mine to part time, but have run into one 350 engine that would not run right with part time, or even with advance even connected at all.

    each engine is different really.

    i would time engine with vacuum guage set it for 18-22 inches of mercury at idle(if is stock cam), i dont even use a timing light ever and i get mine so fine tuned with vacuum guage that you can stand outside of truck and reach in and flip key switch real quickly and will fire right up split second just like its fuel injected. i only run stock Q jets and stock HEI distributors for this reason


    good luck
     
  5. 99firehawk

    99firehawk 1/2 ton status

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    Are you sure You didnt create a vacum leak? or mix up the hoses ?
     

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