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TH400 Vacuum source? ---NEED HELP QUICK! PLEASE HELP!---

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dawson444, Jan 12, 2002.

  1. dawson444

    dawson444 1/2 ton status

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    I am going to be installing a TH400 in my 88K5 soon. Where is the best place to get a vacuum source so I can run a line from it to the tranny? Thanks!
    ______________
    I need to get this hooked up tomorrow, where can I get vacuume from? Please be specific! Thanks!

    Dawson
    Raleigh, NC

    88 K5, 6" lift, 36" TSL Radials, 14 Bolt, Rancho 9012s<P ID="edit"><FONT class="small">Edited by dawson444 on 01/19/02 10:38 PM.</FONT></P>
     
  2. chvyhs

    chvyhs 1/2 ton status

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    Re: TH400 Vacuum source?

    What tranny do you have now? Is it carburated or fuel injected. Look for a vacum port approximately the same size as the vacum modulator port.

    <a target="_blank" href=http://community.webshots.com/user/chvyhs>WebShot Pics</a>
     
  3. TheGeneral

    TheGeneral 1/2 ton status

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    Re: TH400 Vacuum source?

    Dawson, I used the brake booster vacum after switching over to hydroboost. I made it a hard line down to the modulator. Worked pretty good.

    If you ain't hurt, you ain't playin' hard enough.

    The General
     
  4. dawson444

    dawson444 1/2 ton status

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    Re: TH400 Vacuum source?

    I have 700R4 now, and I have FI.

    Dawson
    Raleigh, NC

    88 K5, 6" lift, 36" TSL Radials, 14 Bolt, Rancho 9012s
     
  5. dawson444

    dawson444 1/2 ton status

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    Re: TH400 Vacuum source?

    Can I put a T into the brake booster line and run vaccume boost and tranny off the one line? Is the fitting on the 400 ment for a hard line of a soft line? Thanks!

    Dawson
    Raleigh, NC

    88 K5, 6" lift, 36" TSL Radials, 14 Bolt, Rancho 9012s
     
  6. 85HeartBurb

    85HeartBurb 1/2 ton status

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    Re: TH400 Vacuum source?

    i have a 88 th400 my source is a port just behind my tpi the same size as off the modulator!!!!

    NO LOCKER, STOCK GEARS, NO PWR BRAKES, NO POWER STEERING, NO PROBLEM!

    HIT IT FULL CHICKEN!!!!
     
  7. HarryH3

    HarryH3 1 ton status Author

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    Re: TH400 Vacuum source?

    And the answer is: Manifold vacuum. A port that comes directly out of the intake manifold will provide the signal that the modulator needs. You don't want to use ported vacuum from the carb or you'll confuse the heck out of the modulator. The stock configuration uses a hard steel line with a few inches of rubber tubing at each end.

    Don't forget that you'll also need to install the kickdown switch for the Turbo 400.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  8. dawson444

    dawson444 1/2 ton status

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    Re: TH400 Vacuum source?

    Where can I get manifold vacuum? I need help! Thanks!

    Dawson
    Raleigh, NC

    88 K5, 6" lift, 36" TSL Radials, 14 Bolt, Rancho 9012s
     
  9. dawson444

    dawson444 1/2 ton status

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    Re: TH400 Vacuum source?

    What does the port go to? Or what is it suppose to go? Thanks!

    Dawson
    Raleigh, NC

    88 K5, 6" lift, 36" TSL Radials, 14 Bolt, Rancho 9012s
     
  10. dawson444

    dawson444 1/2 ton status

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    Re: TH400 Vacuum source?

    What does the port go to? Or what is it suppose to go? Thanks!

    Dawson
    Raleigh, NC

    88 K5, 6" lift, 36" TSL Radials, 14 Bolt, Rancho 9012s
     
  11. HarryH3

    HarryH3 1 ton status Author

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    Re: TH400 Vacuum source?

    There are ports on top of the intake, usually towards the rear. Look for a port that just feeds directly into one of the intake runners. That will be where you get full manifold vacuum. Edelbrock intakes usually have several intake vacuum ports already drilled and tapped. The largest is the feed for the power brake booster, but there are usually several others.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  12. dawson444

    dawson444 1/2 ton status

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    Re: TH400 Vacuum source?

    I just tapped in to the brake booster line. I hope to know if it works at the end of the week.

    Dawson
    Raleigh, NC

    88 K5, 6" lift, 36" TSL Radials, 14 Bolt, Rancho 9012s
     

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