Let me "fire" this subject up again. My 1980 1500 pump DOES NOT have the drain/fill-level screws in the pump housing either. I only want to have to tackle this one time and be done with it. I do plan to remove the cover when I drill-n-tap and then clean it all out real good....BUT....my question is, what size bit and tap did anybody use?
A 1/4 x 20 looks about right as far as diameter goes, but I don't know how much of a boss I have for the course threaded bolt to grab and am thinking a fine thread should be used, or maybe even a 1/16th. pipe plug. I forget what the threads are on the plug that is a step below the 1/8 NPT plug, but I have a few of those that came out of Harley EFI lines I have accumulated over the years. The plug is used in a fuel pressure port for testing on the fuel injected models. A plumber friend of mine told me there was no such thing as a 1/16th. pipe plug when I went in to purchase a tap....but I have a few that I call a 1/16th. because they are a step below a 1/8th. and look like they will fit these bosses on the pump just fine.
In any event....what did somebody that has actually made this modification use?