System vacuum

Discussion in 'General Ranchero Help' started by Gregory Cummings, Feb 13, 2020.

  1. Gregory Cummings

    Gregory Cummings In Second Gear

    Messages:
    83
    Location:
    Oceanside, CA
    smog_schem_marked.jpg
    "int man" and "man vac" Which is which. Where are they located. And which ports on the carb C, CS, E, V, BV. CS=cold start I hope.
     
  2. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    9,684
    Location:
    Everett, WA
    "Int Man" is the port in front of the carb. "Man Vac" is the vac tree behind (hence the 'hex' shape) the EGR on the manifold. V=Venturi vacuum. S=Secondary vacuum, which kicks in after the engine warms up. E used to be straight EGR control vacuum, but with everything all complicated, who knows now? Babe's engine only uses the manifold and secondary for ignition timing, and venturi vacuum for EVAP. That's all I see for now.
     
  3. thebruins

    thebruins In Second Gear

    Messages:
    36
    In your schematic:
    I think the S port provides vacuum to the distributor, regardless of the engine's temperature. The VCV it is connected to allows the engine to give full manifold vacuum to the distributor when the engine is close to overheating and by doing so it increases the engine speed to speed up the fan.
    E port is connected to a VCV that allows the purging of gas fumes once the engine has warmed up a little.
    V port is EGR.

    But you posted a different schematic a while ago, so who knows how it is supposed to be hooked up in your car.
     

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