The usual fuel line configuration is a 1/8" NPT female thread at both the fuel pump and the carburetor with brass or steel adapters threaded into them to convert to either 1/4" or 5/16" OD steel or cupro-nickel tubing with inverted flares at both ends. The flare fittings do not require thread sealer, but the male pipe threads on the adapters can leak if they're not sealed. I use a gasoline resistant brush-on liquid sealer (sparingly) such as Permatex Super 300. Super 300 was developed back in the 1950s to be used on fittings exposed to aviation gasoline, and it's by far the best liquid sealer I've ever used. It's a little difficult to find- - - -I think NAPA stores list it as a special order item, and I can usually find it on Ebay with a little searching. Good luck!

shop.advanceautoparts.com/p/permatex-super-300-form-a-gasket-sealant-non-hardening-4-ounces-80057/7010206-P

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!