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Vacuum gauge

Discussion in 'The Hokey Ass Message Board' started by bogart62, Jan 9, 2013.

  1. bogart62
    Joined: Dec 20, 2006
    Posts: 180

    bogart62
    Member

    Would like to install an old Motor Minder vac gauge in my ;55 GMC. I don't have a separate source for vacuum. Should I tee into the power brake vac line? PCV vac line? or vacuum advance line? Don't have a fitting or plug in the intake. Looking for a clean connection. Would the above listed sources work? Thanks for the help. Kent
     
  2. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    any place that is convenient.
     
  3. bogart62
    Joined: Dec 20, 2006
    Posts: 180

    bogart62
    Member

    So if I tee the vac. advance line I won't mess up anything with the distributor? I guess it's a closed line right? Thanks
     
  4. propwash
    Joined: Jul 25, 2005
    Posts: 3,858

    propwash
    Member
    from Las Vegas

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  5. bogart62
    Joined: Dec 20, 2006
    Posts: 180

    bogart62
    Member

    ok will give it a whirl. Thanks, Kent
     
  6. noboD
    Joined: Jan 29, 2004
    Posts: 7,105

    noboD
    Member

    If it's not a closed line there's a leak.
     
  7. Muttley
    Joined: Nov 30, 2003
    Posts: 18,376

    Muttley
    Member

    Yeah, I've got a Sun Vac-O-Meter in my Comet and I pay closer attention to it than any other gauge in the car.
     
  8. Joliet Jake
    Joined: Dec 6, 2007
    Posts: 489

    Joliet Jake
    Member
    from Jax, FL

    Does the GMC's distributor vacuum advance source only pull vacuum when the butterfly opens like most early vacuum advances do? If so, wouldn't it be the wrong place to install a gauge? I have always installed the gauge on a "manifold" port where it can monitor true manifold vacuum, low gauge number means throttle open, or under acceleration, high number was fuel economy.
    Just asking
     
  9. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    No "most" vacuum advances get hooked up to manifold vacuum on the engines that we are talking about. Some Fords up to 56 used a different vacuum source but all the GMs from the 50s/60s are manifold vacuum and all the vacuum does is pull on a diaphragm to change the advance a spring retards it when the vacuum drops.
     
  10. bogart62
    Joined: Dec 20, 2006
    Posts: 180

    bogart62
    Member

    Tommy, so teeing into the vac advance line that comes off the carb will still be ok for my vac. gauge?
     
  11. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    Sure as you watch the needle on your gauge fluctuate back and forth, the vacuum advance is doing the same thing inside the distributor.
     
  12. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,283

    el Scotto
    Member
    from Tracy, CA

    Yep, make sure you tap into manifold vacuum, not ported. ;)
     
  13. bogart62
    Joined: Dec 20, 2006
    Posts: 180

    bogart62
    Member

    ok thanks again.
     

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