The Stovebolt Site Forums The Shop Area Engine Shop Copper fuel lines

In the last few years, I am seeing a trend by fellows using copper fuel lines in their hot rods.

I like the look of polished cooper...it looks classy with brass fittings and adds a nice touch to an engine bay.

I was always told copper was a bad thing to use for fuel lines.

Is this a myth?

I would appreciate your comments!

Greg

copper is a bad thing to use for diesel or bio-diesel as it will oxydize the fuel, don't know about gasoline

problem I'd consider with copper would be makeing good bends without crimping the flow at all, and making good liquid tight joints that can handle repeated tightening and loosening, as well as exposure to heat - it's regularly used for LPG and natural gas tho

Bill

Copper was used as original equipment for fuel lines on many vehicles through at least the late 1950's.

Jon.

By the end of the 70's and into the 80's, it was discovered that copper could no longer be used as a means to move natural gas. It was discovered that natural gas will slowly deteriorate copper lines from the inside out. You can no longer use copper lines in any kind of construction.

The biggest problem with copper is that it is soft enough to fracture if it used in any type of situation where there is movement and vibration of the lines.

Joe

Hy guys, the buses I started working on thirty years ago [diesel] routinely used copper fuel lines I never experienced a problem with them except where they went through the bulkheads and the grommets deteriorated.

Joe, that's a suprise - here in Canada copper is common and legal for natural gas in a building - my commercial equipment has been workin fine w/ soft copper drops off black iron distribution lines

Bill

Huh...We have a big diesel generator at work with copper fuel lines. It's 1950's vintage though.

I've been building houses in Texas since 1969 and in the late 70's, or so, we had to stop using copper lines for any drops. All drops had to be done in black pipe and it is still that way today. Copper drops equal a Red Tag. I've even had to change from copper to black pipe on remodel jobs where we weren't actually working with anything to do with the copper. They have made us change it out if they see it!

We can use the polyurethane and flex, but no copper.

Joe

differant grades of copper. Rubs through if moves agaist any thing. compression fitings are tight to 200 lps water pressure. copper looks good. no efect by gasoline that i know of. inspect regulary for problems. use a tubing bender the type with wheels.

The issue that I know of with copper is fatigue from bending. This can happen most when you have a copper line running from the engine to the body or frame. The engine moves independently from everything else. This can be reduced by making coils that take up the movement. After time cracks can appear and then you have a failure. My 1960 Austin Healey Sprite has had copper fuel lines since new and they are still fine. I used copper on my rebuild of my 1940 1/2 ton. Go to my web site and look around on the current progress. I have pictures of my engine with copper fuel, vacumn and water heat for the intake manifold.

bill's right
we have made copper lines on old motocycles and incorperated a full 'loop' to give a bit of spring/flex to the otherwise rigid line.

My '31 Olds uses copper from the fuel pump to the carb. I replaced the original lie because it had chafed against the block. The vacuum line for the wipers is also copper and has a full turn loop between the intake manifold and poit where the line is secured to the firewall. This line is original and shows no sign of fatigue after 75 years of use. So, if you like copper, use it. Just watch where and how you route it.

Many things have used it for fuel lines before.
But now people think it is likley to crack, and that is bad if it has gas in it and is near a hot engine.

I would use regular steel or stainless myself.

I think I have heard that it may be illegal to use copper for fuel lines in some states? like you should fail an inspection if you have copper fuel lines. I am not for sure on that though.

I agree with with Grigg. Better to use steel or stainless lines.

As stated earlier copper tends to work-harden from vibration and then cracks can then develop. If you are running a electronic fuel injected engine then there is even more pressure inside the fuel lines (up to 80 PSI or more in some cases) increasing the chances of leaking.

Adam

Thats why when copper was used in any aircraft they specified a "hold down" clip at certain intervals. To keep the lines from vibrating and cracking etc..... above all else. Be safe!!

I just finished re-plumbing an old Stovebolt that had plasic tubing-like you use on your swamp-cooler-for fuel line from the rear tank to the valve by the left rocker panel. It went through holes in the frame,over the frame,across the driveline,around the frame rail,through a hole in the crossmember,made a big loop ahainst the floorboards,and went across the driveline again,over the frame rail into the change over valve.(about 15 feet of tubing) Runs a TON better now.
Speed

If the for what its worth category regarding stainless steel fuel lines:

We have been bending fuel lines for factory multiple carburetor setups for years. Some 20 years ago, we discussed making lines from stainless steel, and contacted one of the large stainless manufacturers. We were granted an interview with their engineering department. The engineers stated quite positively that this MIGHT be a very bad idea. According to the engineers, stainless flares should NEVER be bent more than 37 degrees. Automotive fuel fittings are 45 degrees. The chief engineer suggested that if we were going to make lines from stainless, that we should also make 37 degree fittings to use with the lines. We decided NOT to fabricate any lines from stainless.

I realize others are using stainless, however the above is the "skinny" from someone (the chief engineer, not me) who should know.

In 40 plus years of working on fuel systems, I have seen only one failure of a copper line. This occured at the flare (cracked). Subsequent inspection determined that the flare retaining nut had been cross-threaded at one time in its life, which damaged the flare.

However, for "hot rod" applications, we use either steel or aluminum at the customers discretion. We use copper for the Oldsmobile J-2 tripower as that was original, and have had zero problems.

Jon.

Thanks jon

I also have used copper fuel supply lines without a problem.I double flare the ends and always use new fittings.If you want a chrome look, you can use a free standing bathroom sink supply line purchased at Home Depot or a good plumbing store.Looks good and will bend up well.

Fatigue? Many air brake trucks/buses used copper air lines until they were replaced by plastic lines in the 80's.Flex or rubber hoses are used at area of movement,compressor and brake chambers.

Don't know about air brake lines, but I would bet regular brake lines are probably copper/nickel lines. I used them on my 1940's brake lines. I ordered the coils online and bent the lines my self. They are very popular in Europe and again my Austin Healey used them from new. They clean up and shine like gold. If anyone is interested I can supply the link. I'll have to dredge it up.