Thanks Mike B . . I have tried a 1/8" npt plug and it was too large. The plug measures .320" just below the first thread, so it's much larger. I just thought to try a 1/4-28 bolt and it was also too large. My measurements with a caliper have been between .208 and .212" inside the elbow but it is difficult with the new plastic/insulated firewall liner to even get in there for a measurement.
Thanks 3B . . Although it was about a year ago that I took out the brass tubing, I remember it being straight (or npt) threading, no flare? If only the wire wheel hadn't flung the little piece into oblivion!! I will look up the part numbers for the flare plugs and see what I can order. Many thanks for your finding that info.
Always appreciate the knowledge base here with the Big Bolters!!
