Hello and thanks in advance for any help/suggestions. I recently replaced the timing chain on my '69 350. All went well. I replaced the fuel pump at the same time and, after starting the car, found a fuel leak between the brass adaptor and new fuel pump. It was a pretty steady drip. I pulled the line and added some Teflon tape to the brass adaptor. It's a pipe thread so, in theory, it shouldn't need it but the challenge is this fitting has to be clocked in a certain orientation to line up with the original steel fuel line to the carb. Therefore, if it isn't tight enough at the proper clocking position, you need to do something to seal it.
The Teflon tape definitely helped. After a minute or two of idling, I noticed it looked a little wet but the steady drip was gone. Still not tight though. I made the mistake of attempting to turn the brass fitting one more revolution to get it tighter. Made a stupid mistake not getting the wrench on the adaptor fully and ended up pushing the sidewall in. I've got a replacement on order from Inline but my real question is whether any of you have a better solution to seal this adaptor at the fuel pump rather than using Teflon tape? Like I said, it's a pipe thread so it doesn't seat at the base like the fuel lines. I don't think I could have gotten it that extra revolution. It was getting too tight at 180 degrees out so I'm convinced I'll need something to seal it.

 

As I understand pipe fittings DO require teflon tape or a sealant of some sort unless the fittings are nylon or plastic. You could try a couple of extra wraps of tape. Maybe your new fitting will be oriented better.

 

Pipe threads are not definitive. There are TWO kinds of pipe threads.
NPT is National Pipe Taper threads and are cut on an 11 1/2 degree angle (taper) that will seal pretty well in the appropriate mating thread.
NPS is National Pipe Straight is cut straight like threads on a bolt. They will seal as well as NPT.
NPS and NPT threads will screw into each other but not seal. They use the same threads per inch. Its easier to look at them next to each other to see the difference.

NPS threads are used when a you have flared fittings or tubing, such as a fuel line, transmission cooling lines, etc.
NPT is used in such locations as oil pressure sender, water temperature sender, etc. where higher pressure is not a problem.

You can use some sealant for both, but don't relay on it as a complete solution. The teflon paste is preferred, but the teflon tape can work. Make sure you keep the tape 1/8" from the end, wrap twice and add tape as you wrap away from the end. Make sure you don't end the tape ("tail") at the end.
......Just my two cents worth.

 

The fitting on the fuel pump is nothing special. It's just an elbow with male NPT threads and female inverted flare fitting for the hard line. Most hardware and auto parts stores have these. If there's any question about thread sealing due to fitting clocking, use Locktite 567 teflon sealant. I've found this to be much more reliable than any other pipe dope. And naturally, do not use any sealant on the inverted flare fitting, only on the NPT threads.

 

You can use some pipe thread sealant with Teflon available at your local parts store or some Loctite 577 which I use on my cars. Especially on the hydraulic fittings. I try not to use Teflon tape. I have also installed fuel pumps that have the inverted flare built on and made my own fuel line. Good luck and take care.

 

Wanted to loop back and post the resolution so it might help someone else in the future. Looked for Loctite 567 and/or 577 locally with no luck. Found a similar Permatex product (high temp thread sealing paste) and figured I'd give it a try. No good. Still had fuel leaking. Took the adaptor out and cleaned everything off. Went back to the Teflon tape and wrapped it several turns. Installed the adaptor and clocked it but decided to attempt one more turn. Was careful and got it the extra turn but it was definitely tight. Got the fuel line hooked up and everything was dry. Mission accomplished.
Going the extra turn was really what made the difference. Just an FYI, I've had a '69 442 for over 25 years and have replaced fuel pumps, lines, etc. so I'm more than familiar with these brass adaptors. I just never had one give me as hard a time as this to seal.
All worked out in the end! Thanks for all the comments and suggestions.

 

One thing you don't want to do with teflon tape is to back off turning, once turning to tighten.
Another thing is to periodically inspect the fitting. I once used teflon tape for a watter fitting installation. It didn't leak, immediately after installation. But, caught me by surprise, afterwards. I then corrected the leak, using hemp strands. Since it's impossible to get a buzz from smoking the stuff, it's legal here and used by Old School plumbers. The stuff should work for gasoline fitting sealing, if the teflon eventually gives up: