I am pretty sure it is some sort of air valve or something to do with an old car. I have found several Model T Ford parts in this area. Here is a photo. No threads inside, just on top.
Hmmm RF...im a car guy..but not too versed in Model T. Almost appears to be a thermostat-like part...threaded on one end, what looks like a valve or bi-thermal running thru it...good luck! Ddf