What's This Solenoid for?

Discussion in 'The Venerable Q-Jet' started by rkammer, Aug 24, 2020.

  1. rkammer

    rkammer Silver Level contributor

    I've owned '70, '71, and '72 GSs before and don't remember seeing this solenoid attached to the carb top front bolt. This pic is on my just bought '70GS455 w/Turbo 400 and A/C. The intake manifold and carb are both original to this car or, so I'm told. The two electrical connections appear to not be part of the factory original wiring and I can't tell where the two vacuum connections are going. (car is in transit and will be here Thursday)

    1970 Buick GS455_ (30).jpg
     
  2. LARRY70GS

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

    Transmission Controlled Spark (TCS) advance system. It only allows vacuum advance in 3rd gear. If you have any of the Chassis Manuals, just look in the emissions control chapters for a full description of the system. I disable them. Engine runs better and cooler with vacuum advance full time.
     
    Last edited: Aug 24, 2020
  3. rkammer

    rkammer Silver Level contributor

    Thanks, Larry. I don't have the '70 manuals yet as they are coming in the trunk of the car in transit. As you suggest, I'll disable the solenoid as I also like manifold vacuum full time. Thanks again.
     
  4. LARRY70GS

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

    70 and up manuals have a TCS description. The system works the same although the solenoids can differ appearance wise. Here is the 72 section,
    TCS System.jpg
     
  5. rkammer

    rkammer Silver Level contributor

    Thanks again. I've been familiar with the thermal control of the vacuum advance with the 3 connection unit screwed into the water passage but haven't seen the TCS solenoid before. I'll leave them on the manifold for originality but will bypass them for my use.
     
  6. Cliff R

    Cliff R Well-Known Member

    From what I can see the front vent tube is missing from the carburetor and all the front vacuum ports are capped off. No doubt it will need a few thing addressed after it shows up.......
     
  7. LARRY70GS

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

    What you can't see in the picture is the thermovacuum switch.
     

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