Unknown Vacuum Port

[spduffee]

Hello Alll,

I can't seem to upload photos, but I think you'll all know what I am talking about. There is a manifold port in front of the carb with a 3/8"/ 1/2" hose going to the master brake cylinder. On that same port there is a small nib that I just realized is sucking in air. It has no hose on it. I stuck a piece on so I could play with it and sure enough, when I plug it, the engine runs smoother.
Looking at the vacuum diagrams, I don't see any mention of the brake cylinder, but it appears this port goes to the carb bowl, non-linear valve and the HDC CTO. This is how I found it. Is there any reason for this port not to be plumbed? I think I may have to go buy all new vacuum lines and start over.
Thanks,

Shawn

[rang-a-stang]

Honestly, Shawn, when I bought mine, the vacuum lines were train wreck and that's exactly what I did (took em all off and started over). If you still have the vacuum diagram on your radiator support, that's the best one. The factory manual for mine did not show certain circuits like my transfer case switch, Heater motors, cruise control, or brakes. It was night and day difference afterwards, too.

What year and engine?

[spduffee]

Sorry, should have included that in the beginning:
Mine is a 1986 base model Grand Wagoneer, 360 V8. It was a former forest service vehicle, so the PO said.
When I bought her she had been sitting, but was drivable. The air injection tubes were shot, the catalytic converter was bad and so were a lot of the hoses. I read up on the smog system and decided to yank it all. I followed a no-smog diagram I found online but I never even saw the front manifold port until now. I will now revisit that diagram and the factory setup and make the best of it. I really don't understand the theory behind vacuum in an engine and what all happens, so I will do my best by following directions written by those who do.