Columbia Vacuum Plate
 

I'm looking for this item, but need advice as to how large the Vacuum holes need to be to meet the shifting requirements of the vacuum cylinder. Any help appreciated.

Re: Columbia Vacuum Plate
 

Hi Russ,


The vacuum plate connection is 1/4"NPT. You need part number B-49K which has the plate, longer studs and two gaskets.


Glenn

Re: Columbia Vacuum Plate
 

Russ, To get proper vacuum, make sure the plate you get pulls vacuum from
both venturies. There are some plates that only pull from one side. I think
they are for gas fed heaters.

Ken

Re: Columbia Vacuum Plate
 

Hi,


The Columbia is to be shifted with your foot off the gas, i.e., both throttle plates are closed. The vacuum source must be manifold vacuum and not vacuum above the throttle plates.



"The driver then takes his foot off the accelerator pedal (to create maximum vacuum) and fully depresses the clutch which completes the shift."


Glenn

Re: Columbia Vacuum Plate
 

If you have a low-vacuum situation, you can also put in a vacuum tank - with a one-way "flapper valve" - such that you store vacuum. This is the same principle that is used on many brake boosters.

Re: Columbia Vacuum Plate
 

FWIW, when I first installed my Columbia, I drew the vacuum from a T in the wiper supply hose. It was a little slow in shifting, but otherwise it worked fine. (I later installed a supply port in the phenolic spacer under my 4bbl carb, and now it shifts instantly.)

Re: Columbia Vacuum Plate
 

Where do you fine the vacuum plate with part number B-49K?

Re: Columbia Vacuum Plate
 

Columbia Two Speed Parts: http://www.columbiatwospeedparts.com/