I am guessing this is for an external oil line ?
it is very well machined, and threaded,
did they ever come from ford with this hole ?
It's not factory.
Looks like an access hole to check the oil pickup funnel...just a guess.
I'm assemblying an engine with a similar plug. The plug is pretty much in line with the funnel on the internal oil line. If you were lucky you might be able to feed a wire thru the oil line to clear it, or may be maybe get an air nozzle with a tube to blow thru the line. Visability would probably be zero. I would think it would be easy to damage the insulation on the coils.
I'm with Bob on this - access to internal oil line for possible cleaning with a piece of speedo cable.
That hole could be for cleaning the interior oil line. An after market hogs head with removable pedal section had a large hole in the same place specifically for cleaning the oil funnel.
Wasn't there an article on doing that sort of adaptation in one of the "tinkerin tips" books?
It was to access the oil line and clean it out.
The HIMICO set-up is very different but it has a Large hole threaded and plugged in it also, several of us have such an animal
Hey guys, I think it's to access the internal oil line.
Must be an echo in here. Or does no one read previous posts?
I have a similar hole put into an aluminum hogshead, don't know why.
I agree with all the answers above, Echo-Echo-Echo.
Bob