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TBI vacuum line Q's

Discussion in 'The Garage' started by Mastiff, Jun 11, 2004.

  1. Mastiff

    Mastiff 1/2 ton status Premium Member

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    TBI vacuum line Q\'s

    I'm trying to get my vacuum lines right when I go from carb to TBI. I don't have many, just tranny kickdown (TH400), brakes, PCV, and the one for the interior stuff (AC control, etc.).

    Check this out:

    [​IMG]

    I think this is just a splitter thing attached into my manifold to get unported vacuum. The tranny and accessory vacuum are going to it. I'm not sure how it got there, but can't I just run these lines to the throttle body itself and plug this thing up? I'm thinking of the lower right port in this pic:

    [​IMG]

    Make sense? There's a port on the back of the TBI too, but I think it's dedicated to the MAP sensor.

    The other thing I have to hook up is the brake booster:

    [​IMG]

    Where does this go on a factory TBI setup? The guy who made this kit said to hook it to the port up front, so that would be three things to the unported vacuum (lower right?).

    Lastly, here's the hose that connected the brake booster to a rigid line that attached to the back of the Q-jet. What is the cannister thing for?

    [​IMG]
     
  2. jarheadk5

    jarheadk5 1/2 ton status

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    Re: TBI vacuum line Q\'s

    [ QUOTE ]
    What is the cannister thing for?

    [/ QUOTE ]

    It's a filter for the brake booster.
     
  3. Cmoe

    Cmoe 1/2 ton status

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    Re: TBI vacuum line Q\'s

    First Pic is the Ported Vacuum Switch which is a temp. vacuum switch.

    I'm not sure but the PVS is a steady vacuum and the ones of the carb/TBI are variable.... Anyone know for sure...Please step in.....
     
  4. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: TBI vacuum line Q\'s

    [ QUOTE ]
    [ QUOTE ]
    What is the cannister thing for?

    [/ QUOTE ]

    It's a filter for the brake booster.

    [/ QUOTE ]


    No, It is a check valve. Basically a one-way valve
     
  5. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: TBI vacuum line Q\'s

    -Port on BACK of TBI is for the MAP sensor
    -Left-front port (as you are looking at the front of the TBI), labeled the "J" port is for the A.I.R. pump solinoid thingy.
    -Big center port on front of TB goes PCV


    The "T" behind the TB and infront of the distributor is just that...a place to tap multiple accessories into manifold vacuum...(cabin accessories, cruise, etc....)


    The brake booster needs a solid manifold vacuum source..the one on my TBI 454 plugs into the manifold on the drivers side a few inches ender the throttle body. I can't remember where it went on my old 350, but I am sure it wasn't in the throttle body.
     
  6. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Re: TBI vacuum line Q\'s

    [ QUOTE ]
    -Port on BACK of TBI is for the MAP sensor
    -Left-front port (as you are looking at the front of the TBI), labeled the "J" port is for the A.I.R. pump solinoid thingy.
    -Big center port on front of TB goes PCV

    [/ QUOTE ]

    So is the right bottom one unported vacuum, same as that "T" thing?

    [ QUOTE ]
    The "T" behind the TB and infront of the distributor is just that...a place to tap multiple accessories into manifold vacuum...(cabin accessories, cruise, etc....)

    The brake booster needs a solid manifold vacuum source..the one on my TBI 454 plugs into the manifold on the drivers side a few inches ender the throttle body. I can't remember where it went on my old 350, but I am sure it wasn't in the throttle body.

    [/ QUOTE ]

    Maybe I could put the two things goint to that "T" into the lower right port on the TBI, then adapt the place where the "T" is to fit the brake booster?
     
  7. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: TBI vacuum line Q\'s

    does your manifold have plugs in it? Most manifold have plugs in the unused vacuum ports. My BBC TBI manifold has like 3 unused vacuum ports that are plugged. If I were you, I would keep the TBI ports for their intended function and put the vaccum accessories elsewhere on the manifold.

    Chris
     
  8. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: TBI vacuum line Q\'s

    I believe the bottom right port on the front of the TBI is for the EGR solinoid... on later TBI motors, it was the EVRV solinoid.

    Chris
     
  9. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Re: TBI vacuum line Q\'s

    [ QUOTE ]
    does your manifold have plugs in it? Most manifold have plugs in the unused vacuum ports. My BBC TBI manifold has like 3 unused vacuum ports that are plugged. If I were you, I would keep the TBI ports for their intended function and put the vaccum accessories elsewhere on the manifold.


    [/ QUOTE ]

    It's an Edelbrock performer. I don't think there are any unused plugs just floating around, which is probably why I had that tower of splitter thingy. Thing is, I don't have any of the stuff that the TBI ports are intended for, so I either plug them and have that ugly thing in back, or use 'em for something else.

    What I decided to try was adapting to the big opening in the manifold for the brake booster and then putting accessories and tranny on the unported spot on the throttle body.
     
  10. jarheadk5

    jarheadk5 1/2 ton status

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    Re: TBI vacuum line Q\'s

    [ QUOTE ]
    No, It is a check valve. Basically a one-way valve

    [/ QUOTE ]

    My Haynes manual calls it a filter...
    But Haynes has been wrong before.
     
  11. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Re: TBI vacuum line Q\'s

    I asked the guy at the parts counter what it was and he said "check valve", but when I got a replacement, it said "filter" on it. Air goes through both ways, so I think it's actually a filter. I may have wasted the $11 (/forums/images/graemlins/eek.gif), but I guess it is 22 years old so what the heck.
     

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