42-48 flathead timing cover question

Ok I know im over thinking things and thus has caused me to draw a blank on this one..but what does the little port on the drivers side portion of the timing cover at the top, and then it runs down to the dizzy....what does that do? is it an oiler? and does anyone know what size thread that is...stupid i know but after working 65 hours last week and no days off..well this has got my head swimmin

 

That is the vacuum hookup for the brake on the distrib...runs to manifold vac.
Be sure your distributor has good rubber in the mating flange. This strange setup just makes the distributor easier to work on, leaving only two bolts to pop it out.
Fitting is an oddity similar to a compression fitting but different, available from the Ford parts places. Other end can be whatever works on your setup, was originally a banjo fitting.

 

Thanks Bruce!..you the man!

 

Rubber: C&G sells a kit...just grab the centerpiece with a #6 tap and yank...probably you could find an O-ring that will fit the little well and save ordering an original type.