Vacuum Port on Bottom of Airbox - What goes there?

[Ltanderso]

I’m in the process of replacing a blow airbox on my 1980 911sc. On the old airbox, there is a port inside the airbox that is filled with silicone sealant. There’s no hose connected to it. On the new airbox, the port is there and not filled with sealant. What’s supposed to go here, or is it normal to plug this hole? Here’s the port I’m asking about:

[rwest]

There should be a tube that goes through the engine tin and is open to the air underneath the car. It is a drain to drain oil or water that might accumulate in the airbox.

Because the part of the airbox is where the filter is, it is not part of the sealed system, so won’t be a vacuum leak.

[Ltanderso]

Got it. Thanks for the clarification. I didn’t see any drain line in my engine bay. I searched through various threads on the drain system, and one thread mentioned that there is no drain system for the SCs. Is that correct? Was this port plugged from the factory? I have a US spec 1980 SC.

[Flat6pac]

The port was used 73 through 77 before the oil tank was a sealed system. The fume hose from the tank to side on air box lead to the need of the drain.
The 78 to 83 the oil fumes are burned in combustion through the hose from the tank neck to the back of the throttle body rubber cover.
Bruce

[PeteKz]

At this point, you can just plug it.