I noticed that my once tight aluminum NPT elbows on my pot metal Holley mechanical fuel pump have become "loose". They weren't leaking, but could pretty easily rotate back and forth. I used teflon tape the first time on them, pretty slick stuff. Is there some other sealant that's good for gas that might help hold a torque a little better?

Theres thread sealant made by either permatex or locitite cant remember but its a small tube of paste that works pretty well... Available at autozone etc. Really teflon tape is not recommended for fuel lines anyway.

Teflon in any form is not going to help them stay tight as it very slippery.

I would use thread sealant paste with teflon, Its not a loctite but more of a sealant, i would use it but crimp off the fuel line and clean the threads on the fitting and pump, make sure both are clean and dry with some brake cleaner or something, make sure its dry and clean when you put the thread sealant on

rotate another 360 degrees ,that should tighten em up! BTW you can get a form of tflon tape at homedepot etc ,that is made for fuels. it is kinda yellow.

The fuel lines on our Holley have the flared ends on the tubing. It is the flare that seals, not the threads.