Vacuum Line at Carb Question (1 Viewer)

[PabloCruise]

Here is the page showing the physical layout and the functional schematic for all the Fed spec emissions systems.

I also did a higher res scan of the Layout in case that can help people wanting to refresh their vacuum lines. There are a number of "T's" in the system that are hard to pick up on if you look at the schematics only:

 

[PabloCruise]

Next is the Evap system.

The manual did not provide a layout diagram, only the schematic.

Note the reference to a BVSV, but it does not specify what color the VSV is. The chart shows the VSV opening at 140 F and being fully open by 165 F. This corresponds to the BROWN VSV used for the Spark Control system, but the schematic is not enough to show you where they connect these systems.

 

[PabloCruise]

Next is the Throttle Positioner (TP) System.

This system looks fairly simple - no BVSVs, but it does route through the VSV box located inside the drive side fender apron.
It relies on a ported vacuum signal to keep the throttle a little more open when decelerating at speeds over 14 MPH:

 

[PabloCruise]

Next up - I thought I would include this page that lays out the VSV ports.

There are some differences for High Altitude:

 

[PabloCruise]

Next - the Spark Control (SC) system.

This system uses ported vacuum and the BROWN VSV. Note the operating temps for the BVSV in the table at the bottom.

The vacuum line shown at the T from VSV port 3 is connected to the Evap VCV.

This seems like a crazy system with a big loop of vacuum line, Ts for the Advance and Retard ports and then a connection to the air cleaner that orifices on either side of a connection to the air filter.

I cannot imagine the amount of design and development work that went into this one.

Clear as Mud?

 

[PabloCruise]

The EGR system:

This system uses ported vacuum, through the BLUE BVSV, controlled by 2 ports on the VSV to open and close the EGR valve which ultimately recirculates exhaust gases back into the carb to mix w/ fresh air and fuel.

Note the different temps for the BLUE BVSV - it starts to open at 104 F and is fully open at 129 F. This is a colder BVSV than the BROWN one, and is mounted higher in the thermostat housing.

 

[PabloCruise]

Last up is the Air Injection (AI) system.

This system uses fresh air from the air pump to ultimately be mixed with exhaust at the AI manifold, near the exhaust manifold. There is a Air By=pass Valve (ABV) that injects fresh air into the exhaust when idling or Cruising, and does bypasses the fresh air when decelerating.

The vacuum source/signal comes from the gas filter on the intake.