vacuum control valve

[bostterr1]

hey all
i have a 1979 chev 4x4, with a 6.2 Turbo, 400 trans
my question is do i hook the line from the vacuum pump to the vacuum control valve, down to the transmission?
my vacuum pump is on the serpentine setup, and im using a mechanical wastegate controller,
any help would be apreciated

[Robyn]

The vacuum valve on the IP (For TH400 or TH350 tranny) controls the amount of vacuum to the modulator on the transmission, thus controling throttle pressure.
The vacuum valve has two ports, one connects to the vacuum pump and the other connects to the modulator

If you hook it up backwards things wont work right. You should be able to find the schematic for this in most 80's service manuals.

If not simply hook the thing up and then hook a vacuum gauge to the line going to the tranny.

With the engine running and the throttle at idle the vacuum reading should be fairly high and as the throttle is opened the vacuum will drop.

This simulates the manifold drop of a gas engine under varying throttle plate angles and allows the transmission throttle pressure to vary along with the load.

Too low a TV (Throttle pressure) and the shifts will be soft and mushy and you can burn clutches.

If you find that the shifts are harsh and late then you need to adjust the valve so the vacuum is slightly higher for any given throttle opening.

Hope this helps

Robyn

[bostterr1]

thanks very much,
that info is exactly what i need:)

[Robyn]

You are very welcome

If you find yourself needing a new vacuum control valve the GM number is
#14057219

Many GM parts guys cant find this in the system as it's listed as a switch but on the box it says VALVE

Best

Robyn

[bostterr1]

Do you know if i hook my boost gauge through the same vacuum line?

[Robyn]

The boost gauge is to be connected to the "top Hat" or air plenum on the engine.
This is down stream from the turbo.

If there is not a tapped hole, you will need to remove the top hat and drill and tap a 1/8th pipe threaded hole in the aluminum plenum.

Be sure to clean out any and all debris left from doing this before reinstalling the top hat.

The boost gauge measures manifold pressure and has nothing to do with the vacuum hoses.

Hope this helps

Robyn

[bostterr1]

excellent, thank you.....

[Robyn]

:D :D:):D:D
Robyn