1966 Porsche 912 with 1968 engine. We have these ports coming off the inside-side of the manifolds. Each one has what seems to be hardened rubber tube (not sure if it was always hard or if it's just hardened with age) ending in a screw coming off of it. You can see pictures of it with and without. It's not actually part of the carb. I can't locate it in either of our manuals (912 Handbook and Clymer). Our best guess at this point is something to do with the primitive emissions system. Does anyone know? Click here for the first picture:
Port with Tube & Screw Click here for the second picture:
Naked Port