The fitting has to be turned to just the right angle.
1/8″NPT (National Pipe Tapered) is a self sealing thread
commonly used where a liquid or gas tight seal is required.
Zerc fittings, pipe plugs and pipe fittings may be NPT of one size
or another. Cutting a tapered hole so a tapered tap can make a tapered thread is labor intensive,
A possible problem may be that the original fitting was replaced
by a fitting for a larger size outlet tube. Even for correct size
outlet tube some fittings are not as compact as the original fitting.
There are also small fittings with a formed tube soldered into the fitting.
it looks like a Streamline item made by Mueller Brass Co here in Port Huron for the plumbing trade.
The cowl /carburetor cover casting is fragile , so often missing or
if present broken, Reproductions were available at one time and
may still be. The cowl/carburetor cover for twins seems to be of much more substantial and much less often missing.
