Air box drain

There is a 1/8" plug, just after and level with the bottom edge of the last air box cover under the manifolds. That's it.
You may already have a rigid tube attached pointing straight down to the bilge OR into a puke recovery bottle.
Why are you asking? You talking with the hot rod SFBs about a air box/drain check valve?

I'll be a on small (long) dock between Lambs and Huckins. Cedar Point dock.

You have been reading more junk again. Nothing is going to drain from those holes.

There is crap in there (not mine).
When you get the engines up to temp, the air box slobber is blown into the liners, digested, burned & out the exhaust.
#6 left & right take most of this abuse when you start the engines up. That blue smoke you may see when lit cold.
What is left is close to tar. When hot enough, it will flow into the liners and get digested also.
One of the reasons the DDs need to get run up after long low speed runs.

On the TAs there is usually a check valve that allows the air box to drain into the sump or remote bottle.
I installed these check valves on my TIs long ago. It takes two years for enough slobber (2") to collect before I change the collection bottles out.

I'm working on an old pair of TAs now. The tar has clogged the check valves. No big deal.

Run your boat with good oil and fuel. Run her up every now & then. IMO, Don't open anything up (plugs, lines), You will find Pandora... She is not forgiving or pretty...

What's it not doing? I'm installing new ones vs rebuilding.

Lets close your Air box drain thread.
I hope I talked you out of messing with it. Didn't notice any others chime in.

Open a new thread on your windlass issues with the mfg, mod, voltage and if it's original equip. I assume it's original Galley Wench junk (reef material)...