If you are talking about the vertical port in the picture, it is actually used to retard advance for emissions. I recommend putting a cap on it to keep out debris, unless you intend to use it and sacrifice some performance for the environment. The horizontal port not visible in the picture should be hooked up to ported vacuum from the carburetor.
'65 Coupe, 302, Autolite 4100, C4, 2.80
'72 Grande, 351C, Motorcraft 2100, FMX, 2.75
Last edited by Joe; 01-02-2013 at 02:16 AM.