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Brock commodore rough idle and hesitant take off

Discussion in 'VL Holden Commodore (1986 - 1988)' started by Bulldognz, Jan 11, 2020.

  1. Bulldognz

    Bulldognz New Member

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    I believe I have a vacuum leak but appears someone has taken a lot of the polution stuff off or bypassed so I'm not sure what still needs to be there or plugged. I want to make sure I've checked everything before considering taking the inlet manifold off to check the seal.

    Here's some pics
    [​IMG]

    [​IMG]

    [​IMG]
    [​IMG]


    Any help much appreciated as the old girl goes pretty good otherwise.

    Craig
     
  2. Smitty

    Smitty Well-Known Member

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    .. someone has had a bit of a play there

    for starters, EGR vac hose is missing...
    and the manifold vac tree.. has a screw in one branch !
    (vac leak happening there I reckon)
     
  3. krusing

    krusing Well-Known Member

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    The Vac tree has 2 screws in it,
    for the case of the exercise, just place a bit of Vac hose on both vac tree ports
    [it will go now where, but at lease its seals it correctly],
    then investigate further.

    I noticed you have spark plug leads running under other plug leads on the dizzy cap,
    I would move them so they are not under each other, but over and around t he others.
    Also, check your Dizzy Rotor, Dizzy Cap end clean them, by removing the burnt carbon onthe inside of the Cap, & check Plugs and re-gap them on those motors, the Electronic ignition had issues, if they were not setup or configured correctly, it would play havoc with idling.
     
  4. Bulldognz

    Bulldognz New Member

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    Awesome thanks guys I'll give it a go today. I put some screws in the front facing vac lines (assume they are) on the manifold lightly as I wanted to make sure they weren't leaking. Appears not to be them at all. Wondering if these actually do anything?

    Forgot to mention I replaced all the plugs and HT leads

    So I should focus on the rear vac tree. Are you saying I should run vacuum tube but to where? Or should I block them off somehow?
     
  5. Smitty

    Smitty Well-Known Member

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    to further explain...

    [​IMG]
     
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  6. krusing

    krusing Well-Known Member

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    Take the screws out, as they could cause the leak past the threads, unless you have silicon or glued them in,
    Were I said use a bit of Vac hose,
    I meant run it from one of the outlets to the other outlet, as mentioned, it doesn't go anywhere else,
    it just makes sure they [vac barbs] seal better.
     
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  7. krusing

    krusing Well-Known Member

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    Fair Call,
    I guessing they do that as the Dizzy sockets are high.
    When I worked in Workshop years ago,
    I got told NEVER cross them [spark plug leads] over, as they can rub together, and can cause cross fire on other spark plugs if the gaps on the spark plugs are to big, and can cause a miss, especially when the lead insulation starts to deuterate.
     
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  8. Bulldognz

    Bulldognz New Member

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    OK I'll grab some hose today. I realigned the leads on the dizzy as pictured. I also noticed the points in the dizzy were chalky so I sand papered a bit. No difference yet by I'll try hose today.

    Another question where should the dizzy vacuum advance go into the carb? is on the front right just right of the fuel line?
     
  9. Smitty

    Smitty Well-Known Member

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    hose diagrams..

    from here :)
    https://forums.justcommodores.com.au/threads/quadrajet-pollution-hoses-help-needed.274489/
     
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