ported vacuum switch

Discussion in 'Wrenchin' Secrets' started by Gold GS, Jun 18, 2018.

  1. Gold GS

    Gold GS Well-Known Member

    Hi Everyone, I found what looks like a broken ported vacuum switch on my intake manifold. There are no vacuum hoses going to it and the top looks like there was a plug that goes into it. (it's broken now). Does anyone know what the function of this part is and where to the vacuum lines go? Thanks for any help in advance.
     
  2. Gold GS

    Gold GS Well-Known Member

    The car is a 1972 Buick GS 350
     
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Part of the TCS Emissions control. Bottom line is you do not need it. The engine will run better without it.

    TCS System.jpg
     
  4. Gold GS

    Gold GS Well-Known Member

    Thank you Larry. I'll just put some plugs on the two vacuum ports.
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    No need, there's no vacuum there unless it is hooked up to the vacuum. That switch sits in a coolant passage. Better yet, pull the whole switch and put a gauge sender for temperature in there.
     
    Last edited: Jun 18, 2018
  6. Gold GS

    Gold GS Well-Known Member

    Thanks again Larry, I'll take your advice.
     
  7. 1968_GS400

    1968_GS400 Founders Club Member

    This is what I want to do. Pull the whole switch and put gauge sender there, hooking carb straight to vacuum advance. If you do that, what do you do with lines from air cleaner. Just plug up the air cleaner line that originally went to tee that connected vacuum switch? But keep the recirculation air cleaner line (what I think is for air recirculation).
     
  8. 1968_GS400

    1968_GS400 Founders Club Member

    For a 67 430 on a 68 GS 400 with a 68 Quadrajet, what vacuum port on the carb would you recommend connecting to the vacuum advance if pulling the vacuum switch, the ported or the manifold, and then what ignition timing to use for daily driving (not racing) use, the 67 430 or 68 timing?

    Thank you in advance.

    I saw your related post here:


     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You can try both ported and manifold to see what you like better. At part throttle, vacuum advance will be the same. Manifold will give you vacuum advance at closed throttle. Like any Buick engine, WOT timing of 30-34*. Initial timing will depend on how much mechanical advance there is in the distributor that is currently installed in your engine.

    https://v8buick.com/index.php?threads/power-timing-your-buick-v8.63475/
     
    1968_GS400 likes this.
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The air cleaner line gets manifold vacuum.
     
    1968_GS400 likes this.
  11. 1968_GS400

    1968_GS400 Founders Club Member

    So you run the air cleaner line to a tee that connects manifold vacuum port on carb to vacuum advance?
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You could. There are a number of ways to do the same thing. Depending on the year/model of carburetor, there may be more than one manifold vacuum nipple, or even one on the intake manifold itself.
     
  13. Duane

    Duane Member

    If you do want to replace the vacuum tree I might have one for a 72 350.

    If memory serves me correct they look like a regular 70-71 vacuum tree, with the brass base and pot metal tree, but have a small tank at the top with a nipple for a vacuum hose connection.

    Just let me know if you want one.
    Duane
     
  14. 1968_GS400

    1968_GS400 Founders Club Member

    I just bought a Standard Motors PVS1 replacement. It looks somewhat different. I think the original was a Delco Remy 3029763 which has like a 1 1/4” nut on it. That was later replaced by one that looks close to the Standard Motors PVS1 you can buy today.

    NOS 3029763 are going for $100-$200 on eBay. A new PVS1 goes for $30 at O’Reilly’s.

    But the one off a 72 350 probably is the 3029763 if it looks like this.

    F481619C-ED73-45F3-A8F4-3D845F1BC0D3.jpeg

    By the way, the ports are numbered different on the Standard Motors PVS1, 1, 2 and D instead of C, D, and MT. I called Standard Motors and believe it or not D is not distributor. They said 1 was Distributor, D was ported and 2 was manifold on the PVS1. I saw this issue on the Oldsmobile forum, and it seemed like no one knew. It looks like the vacuum hoses go in same order top to bottom as the original 68 vacuum diagram, so hook it up like the vacuum diagram and ignore the labels on the PVS1 switch.
     
    Last edited: Apr 26, 2022
  15. Duane

    Duane Member

    The 72 units don’t look like that at all. I have seen that style on 69 big car motors.

    I just checked mine out and it is for a 72 350 motor with AC.
    Duane
     
  16. 1968_GS400

    1968_GS400 Founders Club Member

    Does it looks like this?

    099D4743-6B22-4E08-9301-001E132036D0.jpeg

    That is 1238524. That is what the PVS1 looks like that you can buy as replacement. Not sure if top of 1238524 is potted metal or plastic. The PVS1 as well as the one that came off my car is plastic.
     
  17. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    This the one you are talking about?
    72TCS3502.jpg
     
  18. 1968_GS400

    1968_GS400 Founders Club Member

    Oh 72 or 73 they went to TVS?
     
  19. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    They are all thermo vacuum switches. The one I pictured has an electrical connection. They are all part of the Transmission Controlled Spark emissions system. Anyone that favors better performance and efficiency ditches the entire system. There are the Concourse Resto guys that want it for original looks. Others think the engine won't run right without it. That isn't true, but they insist they want it.
     
    1968_GS400 and rkammer like this.
  20. rkammer

    rkammer Gold Level Contributor

    Yes. I'm one of those who want the most original look possible but, I've taken a different approach since that evaporative system is for the birds. I install a really pretty thermo vacuum switch on the manifold with three vacuum lines attached to it. But, they disappear under my air cleaner and don't go anywhere. Looks pretty original. LOL.
     
    Mark Demko, Brett Slater and PGSS like this.

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