The Stovebolt Site Forums The Shop Area Engine Shop fuel pump

If the new line came as an assembly with the flare nuts already on the tubing, you have inverted flare fittings. I'm not familiar with the 1941 pump but would expect it to be inverted flair also. Do the new inverted flair nuts match the old ones visually? There is the possibility that the seat in the pump is nicked or rusty but not very likely, the brass nuts should seal quite easily given the soft material although if overtightened they may be distorted. The face of the flair is the sealing surface with flair or inverted flair applications, whereas pipe threads are tapered and the sealing surface is the threads and typically need some type of additional sealer such as liquid sealer or Teflon tape