I'm putting on a new set of Edelbrock heads and a 4x2 intake with new Strombergs. Having a blast. Damn I enjoy this stuff. To paraphrase a fishing bumper sticker... (I don't fish): A bad day in my garage is better than a good day at work.

This is a venerable small block Chevy...

I hope I can explain this well without pics, but I'll post some if needed. On the rear "china wall" at the back end of the lifter valley, there is a threaded port. Maybe 5/16" or so. I've seen a few videos where they tape over this "port" before putting on the sealant. On a few videos there is some kind of wire or small tube coming out of it. On my motor there is a threaded plug on the "port".

What the hell is this port? Why are some blocked and some others used for something?

Thank you in advance guys...