I'm having some difficulty keeping the fuel lines from leaking. I get one to stop and another starts. I've even tried using liquid teflon prior to tightening, BIG MISTAKE!. I've just purchased a new set of lines and blocks (my second set) and new bowls.

I've been told that some of the repro lines are too hard of a steel and are not malleable enough to seat, anybody ever hear of that? I'm probably finish this up by the weekend. Am I missing a step? New gaskets at the bowls, tried a couple of different types, the teflon seem to work the best, snug the larger fitting into the bowl body, hold it in place with a 1" wrench to keep from over tightening while tightening the fuel line fitting, Right?

I haven't heard of that problem with repro lines, but instead of liquid teflon, try teflon tape on the threads of the fittings. That's always done a good job for me.

My mistake there was thinking the liquid would give a better seal, they still wanted to leak, maybe a good thing they did. When I took everything back apart, some of the teflon had ended up in the passage, I mean nice little flakey stop evrything up chunks.

The guy that mentioned about the line material being too hard to deform and seat is actually an engineer from Sweden, he's working for Volvo truck, so I have to put some credence to what he is saying. The first set I put on really didn't fit all that well, had to re-bend most of the pieces. Most parts I've bought from this place either didn't fit or were just dead wrong for the car. I got the next set from the Doc, always had pretty good luck with his stuff. I'll know by this weekend. The first set, we just made up ourselves and never had a problem, but they couldn't be saved, had to cut them off to keep from damaging the carbs. Right now I'm leaning towards the flares just not seating in the bowl fitting. I even wondered if the replating may have had something to do with the leaks, technically it shouldn't but at this point I'm looking at everything. It just ain't fun to clean gas off of a brand new freshly detailed motor.

Are you using stainless-steel lines? They can be a big pain to seat, due to the hardness. I have a ss fuel line on my '74, and it leaked at first, until it finally seated, after many tightenings.
One trick I've used for fittings, is to run some sewing thread around the threads. It sounds goofy, I know, but it works, 90% of the time!
Hope you get it fixed!

I stayed away fro the stainless lines just for that reason. I'm really hoping it's just the set I bought from E. I'm pretty much done with them, it's already cost me one bowl and those old style bowls with the patant numbers are really hard to find.

New lines, new bowls and new fittings and still the same problem. We worked on the install this weekend, minor leaking at first. We re-tightened and everything seemed fine, got the motor good and warmed up, man I love the sound of that big block! The next day, I took it out to the back shop and guess what? Darn thing leaking again! I'm now wondering if I need to retighten them leaking or not while the engine is warm, apparently the cool down had an eaafect on the fittings. This thing is really bugging me!

Man... what a bummer!
Where exactly is it leaking? From the fitting/bowl, or from the fuel line/fitting? Or both? Are all three carbs leaking?

There might be a difference in the angle of the flares on the lines, or even the seats in the fittings. I have run across some steel lines that have regular SAE type fittings(nuts), but the flares on the lines were a different angle(metric, maybe?) than the seats. Never could get them to stop leaking. You could, I guess, re-flare the lines with a flaring tool, just to be certain they have the right flares on them.
If the leaks are from the fitting to the bowl, I have seen some Holley-style fittings that were too short to actually seat the gasket(nylon/teflon) to the bowl. Just an idea you might look into. Ain't nuthin worse than an aggrevating fuel leak!

It's beginning to really bug me. They actually take turns leaking. I've changed fitting gaskets a couple of times. Went from the composite to the steel to the teflon/nylon. Sometimes it's hard to tell exactly where the leak is coming from, bowl fitting or flare. I'm gonna take it all off, check the angle of the flares, some of those lines are so short, it won't be easy to get a flare tool on them, but I'm gonna try to re-flare them too. I just don't think I'd have to put that much torque on them to get them to seat.

Does Holley make a fitting that's longer?