Giulia 1600 intake manifold - bottom middle nipple

[1750s]

While underneath my Sprint for another reason, I noticed a nipple protruding from the bottom of the intake manifold. It is square in the middle of the casting and has nothing attached. No drips noticed and a small amount of gunk accumulated with a gasoline smell. What is this nipple for and is it to be connected to something? An early recirculation/venting method?
Thanks
Russ

[AlfistiSA]

It should have a clear plastic pipe attached to it & it drains the excess fuel off from inside the manifold when you switch off.

The hole in the brass nipple is too small to allow air to enter the manifold & upset the mixture, but will allow fuel to drain out.

Ciao
Greig
Sunny South Africa