Vacuum advance test??

Discussion in 'Other' started by gospdgo, Sep 20, 2007.

  1. gospdgo

    gospdgo Eeny, meeny, miney, moe!

    Wasn't sure where to place this question so I put it in the Mixing shop.

    Anyhow, is there a simple effective way to test to see if the vacuum advance from the dist. is functional? I thought I read you can just - bare with me guys - suck on the end of the vacuum hose and listen for a click or something.:Do No:

    I will accept all the razzing and commentary you guys the dish out - since I've set myself up - as long as I get an answer along with it.:Dou:

  2. austingta

    austingta Well-Known Member

    Have a helper hold the engine at about 2500 RPM or so, and check the timing with the vacuum advance plugged (carb end still attached), record your findings, and check it again connected. The additional timing you should notice is the timing added by your vacuum advance!:TU:
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Even simpler than that. Start the engine. Take a length of vacuum hose and connect it from a full manifold vacuum source to the vacuum advance cannister. You should note a rise in engine speed. You can verify that with a timing light. The timing mark should move up when you connect the hose. You can check avance cannisters, choke vacuum breaks, and modulators with a mity vac (vacuum pump) If it holds vacuum it is good
  4. justalark

    justalark Silver Level contributor

    You want simple.....suck on the vacuum hose to the distrib, plug it with your tongue see if it holds a vacuum.
  5. gospdgo

    gospdgo Eeny, meeny, miney, moe!

    That is quick. So the cannister should not release air but instead hold the suction? Ok, I get it. I have a hose going from the carb (edelbrock) to the dist. About how much vacuum should it have and what rpm should it be tested at (2500)? I have a vacuum gauge.
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The stock vacuum cannister provides 14-18* at 16" of vacuum. Just find a full vacuum port on your carb (The Q-jet has one on the passenger side) or pull a hose off one of the choke vacuum breaks. The cannister will either work or it won't.

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