2bbl Rochester / What does this port do?

Discussion in 'Other' started by christopher m jordan, Oct 22, 2019.

  1. christopher m jordan

    christopher m jordan Active Member

    I have a 1970 Skylark with 2bbl Rochester. I recently replaced it with a new one. On the firewall side there is a port that did not have a hose on the old one. This port is fairly large, and draws a lot of air. What is this? I am guessing that it goes to a charcoal canister. I have studied my manual and so far nothing....although I am sure it is there.....if it is a canister where is it located. it has been cold and rainy here and i need a nice day or 2 to get a look....also there are 2 small hoses on the air cleaner and goes to the carb and the other very short and not connected. I believe the smaller one was never used and looking at one diagram in the manual i could see it unconnected. Please, anyone, who can fill me on this vacuum system with a simple explanation please do.

    I Thank You Kindly,
    Chris
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    No charcoal canister gets full manifold vacuum, ever. The fitting on the back of the carburetor is for the climate control doors in an A/C equipped car. It supplies vacuum to a storage canister mounted to the firewall. The only 1970 cars that got charcoal canisters were California cars, you probably don't have one and even if you did, the connection would be a vent line, not vacuum.

    The hoses on the air cleaner operate the door inside the snorkel. There is a temperature sensor mounted in the floor of the air cleaner. It has two nipples with 2 hoses. One hose goes to the vacuum motor nipple on top of the snorkel. The other hose gets manifold vacuum.
     
  3. christopher m jordan

    christopher m jordan Active Member

    I do and don't understand you. This port has alot of vacuum.....we tried to plug it and the car immediately stalled. Since the original set-up is missing....can a tee off the egr to air cleaner be use to prevent water, dirt, etc from being sucked in by the carb. perhaps a photo or image? I will dig deeper in my manual....cd Buick....is there a manual you use that is a little detailed for repair?
    Thank You for Replying,
    Chris
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    OK, maybe you are referring to the PCV valve? There should be a 3/8" rubber hose that runs from the carburetor to the PCV valve at the back of the intake manifold. I just assumed you wouldn't miss that.
     
    Last edited: Oct 23, 2019
  5. christopher m jordan

    christopher m jordan Active Member

    Yes, I meant PCV. I started this hobby of working on these old cars later in life. Ive always done tune-ups, clutches, brakes but never tore deep into engines......I was a Millwright/Electrician for 30 years so I have a strong mechanical background.....but I do not understand the entire emissions set-ups of cars...but then, does anyone?.....lol....I thank you for taking the time to guide me along....I am a good student and fast learner....looking forward to hearing more from you.
    Chris
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Can you post pictures?
     
  7. christopher m jordan

    christopher m jordan Active Member

    Larry here are some photos of the problem I have. Carb 1 has a clear view of the vacuum port.......I am looking at drawings almost non-stop. What I need is a photo of the setup from someone with the 2 bbl setup......." Every problem does have a solution, it may take a while to find out what it is, but it is there!"
    Thank You, Larry
    Chris Jordan
     

    Attached Files:

  8. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    On the 2bbl carb, that large rear port goes to the PCV valve.
     
  9. christopher m jordan

    christopher m jordan Active Member

    Thank you kindly! Must have been a Tee or some type of hosing there. I wish all problems were easy.
    Sincerely,
    Chris
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Yes, PCV, the smaller port is also manifold vacuum that can be used for the climate control or even the air cleaner.
     
  11. christopher m jordan

    christopher m jordan Active Member

    Larry,
    I totally confused myself....I had thought the PCV was located on the valve cover! Not sure or not if they are on some cars. My son went through his manual and discovered the EGR was behind the Carb....flashlight in hand I went into the darkness opened the hood and saw the grommet for the EGR....it apparently was not there when we purchased the car. We were having difficulty getting to idle smoothly, I am sure this was the culprit. I am now thinking that we should have gone with one of our original plans of getting a 4bbl manifold with 4bbl carb. Do you this modification would upgrade power significantly? Than possibly work the exhaust for bigger flow, for even more power. Love this hobby and myriad of challenges. Thank you again for your help!
    Sincerely,
    Chris
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    There is no EGR on a 1970 Buick AFAIK.
     
  13. christopher m jordan

    christopher m jordan Active Member

    lol..........SORRY ABOUT THAT! I keep calling it and EGR when I mean PCV.......old age???
    Chris
     
  14. Dr. Roger

    Dr. Roger Stock enthusiast

    And replace that accelerator return spring before it snaps. :eek:
     
  15. christopher m jordan

    christopher m jordan Active Member

    Its been awhile but one thing leads to another not always good.......I finally got a guy to give me a hand getting this car started. I replaced the pcv and hose to carb.....could not get it to start! With further experimentation......we disconnected the PCV valve and the car started! We also discovered that by placing a finger over PCV port on the Carb, the car immediately shut down! I placed pcv back in grommet with hose connected and suck in and the manifold is not blocking air flow.....WTF? This is a rebuildt original carb from Rock Auto. The original caught fire on a backfire...my fault...but it did not have 2 diaphrams like the replacement....I don't know what they do and they are removeable....I don't think they effect the way car runs....the pcv IMO seems ok..brand new....could the check valve be the problem? ??? we measured 11" vacuum on the pcv connection on the carb with the engine running....is it even pulling air down the throat??? Doesnt appear to have and electric choke.....could this be the wrong carb....sort of doubt it....The engine when it finally warms seems to run excellent and only has 79k miles on it....could sludge be a problem....we did take manifold off and cleaned out some dirt that fell into carb....vacuumed out not much dirt if any and did not replace gasket...not proper I know...but....seems fine...I am a loss for knowledge and and frustrated....any thoughts or ideas would be appreciated. The PCV and hose were not there when I purchased the car.........Just sitting here Shaking my head.
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Something is wrong. 11" of vacuum is way low. You may have a vacuum leak somewhere, or it could be other problems with ignition timing or dead cylinders. You really need someone with experience to give it the once over.

    How close are you to Letitz, PA?
     
  17. christopher m jordan

    christopher m jordan Active Member

    Larry, thank you for your reply. Do you mean Lititz, PA? If so I live south maybe and hour or less. I am planning on giving this engine a closer look. is this how you would do it? Check Points gap and timing. Compression test all cylinders.....also check plugs for color.....even for spark....check proper cylinder to dist. Change oil have it tested......it does have a bad fuel tank...replacement will be delayed....I thought 11" of mercury was actually high.....no wonder it stalled with finger placement....anything else to check? has new alternator, battery, starter, shocks....lol....could the engine be bad....oh well.....we could always up the ante with a bigger engine and 4spd.....
    Thank you so much!
     
  18. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Yes Lititz, PA. Mike Pesarchick lives there. His screen name is No Lift. Maybe he might be willing to help you. If I was close, I would. Normal vacuum fully warm for a stock engine is at least 18", probably closer to 20". With an unknown engine, you have to check EVERYTHING. Take nothing for granted.

    http://www.v8buick.com/index.php?members/no-lift.8033/
     
  19. christopher m jordan

    christopher m jordan Active Member

    Larry, Wow! I should have checked parameters for vacuum! I preach to my son over and over again about how troubleshooting is and art. I was the "go to" guy in the steel mill as I had been taught time and time again to take nothing for granted. I assumed that this engine sounded really good....no odd noises, smoke, etc......I assumed the guy I bought if from was telling the truth....when you said 11" was a low vacuum it nearly floored me. I know nothing that could cause such a vacuum leak. My son kind of disagreed when I said we could start with a compression test. Than do timing, points and etc. I told him this is the way I was taught....make a list of possible causes.....and thoroughly check them...time consuming for sure. I came up some weird problems on electrical equipment such as carbon tracking on relay boards which would pick up multiple relays at the same time and wreck havoc! Sometimes days and hours were spent tracking down problems....my son is a computer system engineer and thinks you can just type in commands to solve problems.....cars will drive you nuts but that is the allure. I will check further...I don't have a great garage...very cold and dirt floor....I am now wondering if sludge hasn't caused damage....hard to access the condition of a 50 year old motor..... although it does run well( at idle mostly} but.....
    I have communicated with several members of this forum now......I am nothing but impressed of the nice people I meet.
    Thank you
    chris jordan
     
  20. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    Where are you taking your vacuum reading? A fitting in the carb could give you a bad reading if there is something wrong inside it. I would try taking my reading from the rear vacuum port on the intake manifold. That way you can at least confirm it is a carb issue or not.
     

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