pwsusi

I installed a new fuel line to carburetor on a '71 LT-1, and gas is leaking from the metal block where the line splits into two to connect to the carburetor. It's leaking from the fittings that screw into the block. I have them as tight as i can get them, have made sure the flange is properly lined up, and even tried putting some "seal-all" silicone thread sealant on the threads....and no matter what i do it leaks. Any suggestions? I'm at my wits end. This should be simple. Is there a better sealant i can use or other suggestions?

Thanks.

lars

Those are inverted flare connections - they don't seal on the threads, so you can't use a thread sealant. Use an assembly lube or grease on the threads and on the back sides of the flare where the flarenut rides against the flare. This will assure your ability to achieve proper torque before the fittings stop tightening due to galling.

Lars

ignatz

You can get these washers in various soft metals, aluminum, copper that will crush a bit and form a better seal.

https://www.summitracing.com/parts/fss-24328

I don't know why they are listed under o-rings.. Careful alignment is critical as you assemble things. I hold the flared end against the fitting with one hand so I know it will seat squarely and with my other, tighten the nut finger tight so the connection will stay in place until I can get a wrench on it.

dmaxx3500

plumbing supply stores sell those too

sullyman56

pwsusi

Thanks guys. it took a few tries on and off, but i THINK it's holding now and no leaks. I started with the engine assembly lube and then some grease when i continued to have trouble and it seems to be good. Appreciate the help.

Robert Thomas

Man, I wouldn’t drive your car until you are 100% positive the fuel fittings don’t leak. I had a car that used 13 of those and they were a bear to get right. Leaking fuel lines = fire = destroyed car.

Barry's70LT1

I've been using these for years, on those connections, no leaks.

Mooser

Holy Crap, is that for a box of 25 or something?

But seriously, I have used the same type of copper washer to stop a perpetual drip on a stainless steel fuel line that just wouldn't stop weeping at the pump. Handy to have a handful of different sizes in the toolbox.

But more seriously, I'm seeing summit listing this at $8 usd, that's insane...
M

pwsusi

stupid question but which way would these go in? would the narrow side go into the metal block and wide side on the flared fuel line, or vice versa?

Mooser

They follow the same angles as the flare on the fitting, just act as a softer surface that will form to a slightly flawed mating taper



The really good ones (flaretite etc) have a shoulder that holds them onto the male part of the fitting, the cheaper only taper ones you sometimes need to put a spot of grease or something to hold them in place until you can assemble the joint or they slip part way off and get screwed up
M

lars

They're also referred to as "flare savers" in the aerospace industry. They are intended for use on AN-type 37-degree flared fittings. They are not intended for use on inverted flares. On inverted flare connections, lube it up well and make sure that the conical sealing feature in the female part of the connection has not been marred ("eyebrowed") by previous misalignment and over-torque. If the fitting has a mark on the sealing surface it will leak. If the sealing surfaces are in good condition, if tube alignment is good, and if the connection is lubricated upon assembly, it will seal.

Lars

Mooser

But I couldn't find a picture of the 45 degree A/C washers installed

I turned to them as a last resort on my pump/stainless line that just wouldn't stop weeping even after multiple re-tightening / cleaning / re-shaping / cursing. (Carb end of the line is all AN fittings)

M

68notray

BTW there is no sealant I know of that can be used on a fuel system. The gas dissolves pretty much anything in a tube...

Kris_K

This stuff works great for fuel lines.

https://www.google.com/search?q=e85+...X5jCbIQgjYIjwQ