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Power brakes, PCV and 225 V6 with holley carb

Discussion in 'Builds and Fabricators Forum' started by 47v6, Mar 6, 2016.

  1. Mar 6, 2016
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    Guys,

    What are you all doing to plumb the PCV and the booster? T off the back side of the carb? Doesn't that make for poor vacuum at the booster?
     
  2. Mar 7, 2016
    sterlclan

    sterlclan Member 2022 Sponsor

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    I think the check valve in the booster makes up for the lower vacuum. Should hold the vacuum in the booster.
     
  3. Mar 7, 2016
    47v6

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    No one has a Holley carb hooked to a PCV and power brakes?
    Thank you so much for replying.

    I have read that using the port at the back of the crab can cause lower vacuum at the booster and maybe affect braking. I know I have seen this setup before though. What do you guys do?
     
  4. Mar 7, 2016
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    I have a Holley carb and booster but it is a 231. I found a port in the rear of the intake manifold and used that.
     
  5. Mar 7, 2016
    Rozcoking23

    Rozcoking23 RUN & GET BIT! 2024 Sponsor

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    I'm not running a 4 barrel carburetor, (yet), but i plumed my brake booster on one of the empty ports coming directly off the manifold. The PCV valve is attached to the carburetor. When I did my power brake upgrade I did a lot of research on where to pull the vacuum from and everything/everyone said that the best spot for brake booster manifold vacuum was from port located in the intake manifold.
    By the way, I've been watching your build from the beginning, you are doing a great job!
     
  6. Mar 7, 2016
    47v6

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    Thank you for watching and thank you for the reply.
    [​IMG]

    As you can see I have 2 ports on the manifold behind the carb. I don't want to lean out one of the cylinders. It probably will be totally unnoticeable on my POS engine anyway even if i did though. I am also uncertain if the port is really large enough to provide adequate vacuum?
     
  7. Mar 7, 2016
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Use the large port for the power booster. Do NOT put the booster feed and pcv on the same fitting, because it can cause issues with not enough vacuum to operate the booster correctly. Pulling some vacuum for short bursts I'm doubtful it would be an issue using the provided vacuum ports in the manifold.
     
  8. Mar 7, 2016
    nickmil

    nickmil In mothballs.

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    It won't make up for low vacuum to begin with. The check valve is there to hold vacuum in the booster when the vacuum source is low for short periods of time or is lost in case of the engine dying. You still have to replenish the vacuum and only the source can do that. If the source is low to begin with, the booster cannot work correctly.
     
  9. Mar 7, 2016
    47v6

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    Thanks for replying Nick, So I have 3 possible ports to pull vacuum from. One in the carb base and those 2 you see in the manifold behind the carb. The manifold ones are presently plugged. Personally I would like to pull vacuum for the booster from the carb base and the PCV from the manifold where the fitting will be smaller. Is this a good idea? I sure think that brakes are a lot more important that PCV, right?

    Thanks
     
  10. Mar 7, 2016
    sterlclan

    sterlclan Member 2022 Sponsor

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    thanks for the clarification,thats what makes this place great i always learn something. the wifes 258 has both to the same port and seems to work ok
     
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