Any reason NOT to use copper fuel line?

[GreenV8S]

I don't think it's common to use copper fuel lines, and perhaps there's a good reason for that but I don't know what it is. The only possible reasons I can think of are some sort of petrol/copper reaction (perhaps electrolytic copper versus steel?), or a strength/fatigue issue. Neither seem likely to me. Anyone have a definitive reason not to use copper fuel lines?

[Pink_Floyd]

The flow and return lines on my chim are copper.

[Steve_D]

I see no reason not to run copper but would suggest Cupronickel or Cunifer rather than copper as copper can work harden with vibration and break.

Steve

[Snake the Sniper]

What Steve said. I'd go for a large bore kunifer pipe. The fuel pipe down the transmission tunnel on my 7 is kunifer as fuel hose can age prematurely in such a hot oily environment. My car only has fuel hose at either end to allow some flex and ease of connection.

[Sam_68]

Steve_D said:

...copper can work harden with vibration and break.

I lost the clutch on my Elan because a couple of inches of copper pipe at the slave cylinder end had work-hardened though vibration and fractured. If it had been the brakes (single circuit system on the Elan), it might have been a bit interesting.

Having said which, I happily use copper brake line (mainly 'cos I'm lazy and it's so much nicer to work with than stiff Kunifer tubing), but I make sure it's properly clipped to the chassis at regular intervals to ensure there aren't any unsupported sections long enough for vibration to take hold.

Edited by Sam_68 on Friday 24th April 17:41

[GreenV8S]

In my particular case vibration shouldn't be a problem because it's a relatively short section of 15mm pipe supported only by the hoses connecting to it. I can see that a longer run, for example the length of a car, could easily start flapping about.

[Steve_D]

GreenV8S said:

In my particular case vibration shouldn't be a problem because it's a relatively short section of 15mm pipe supported only by the hoses connecting to it. I can see that a longer run, for example the length of a car, could easily start flapping about.

Geees.....15mm. What engine are you running...Merlin?

Steve

[GreenV8S]

Steve_D said:

Geees.....15mm. What engine are you running...Merlin?

Steve

This is the low pressure side, between the tank and the pump. It needs to be low restriction because these pumps don't like to suck (iyswim).

[Snake the Sniper]

At 15mm long you could use basically what ever you want! Nothing that short held up by the pipes is going to fracture.

[spitfire4v8]

I use copper pipe complete with soldered 90degree plumbing connections. been like that for 5 years and never any problems. Mind you the car doesn't get out much these days

[Steve_D]

OK 15mm pipe is a different matter and will likely do the job.
Reference to copper pipe work hardening etc was aimed at the more normal 8mm ish pipes used for fuel.

Steve

[GreenV8S]

Snake the Sniper said:

At 15mm long you could use basically what ever you want! Nothing that short held up by the pipes is going to fracture.

That's a diameter, not a length.

[Pigeon]

GreenV8S said:

The only possible reasons I can think of are some sort of petrol/copper reaction (perhaps electrolytic copper versus steel?)

Petrol is not an electrolyte. No prob there

Vintage cars used copper as a matter of course, complete with attractive curly bits as an anti-vibration measure. Steel is simply cheaper.

I used copper pipe for the return line in a fuel-injection conversion. Only problem I ever had with it was when I took the car off road and grounded it and crushed the fuel line

[Simon Says]

I never had problems running copper pipe 10mm bore front to rear on Fords i used many years ago,you cant have problems with it breaking and fracturing if its secured properly and that goes for all fuel lines,i mean its fuel line after all not wiper washer tubing i would recommend using P clips or similar every 12" or so anyways(but you know that already V8s)so i cant see any reason for not using it

Edited by Simon Says on Saturday 25th April 14:42

[99hjhm]

Sam_68 said:

Steve_D said:

...copper can work harden with vibration and break.

I lost the clutch on my Elan because a couple of inches of copper pipe at the slave cylinder end had work-hardened though vibration and fractured. If it had been the brakes (single circuit system on the Elan), it might have been a bit interesting.

Having said which, I happily use copper brake line (mainly 'cos I'm lazy and it's so much nicer to work with than stiff Kunifer tubing), but I make sure it's properly clipped to the chassis at regular intervals to ensure there aren't any unsupported sections long enough for vibration to take hold.

Edited by Sam_68 on Friday 24th April 17:41

Lotus

As long as the pipe is P-clipped to the chassis... not cable tied, you should be fine. Those rubber lined p-clips are great.

Most 50's/60's and before cars have copper fuel lines as std, and never have a issue.

On my MGB race car, i run aluminium fuel line! Yanks wont use anything less than steel for brakes and fuel.

[//j17]

Provided you are using automotive copper pipe it should be fine.

There are reports from some people that have built fuel rails for DIY fuel injection set-ups using plumbing copper pipe that it reacts with the petrol and gums-up the injectors - though only from some, not from all people that have done it.

[GreenV8S]

//j17 said:

There are reports from some people that have built fuel rails for DIY fuel injection set-ups using plumbing copper pipe that it reacts with the petrol and gums-up the injectors - though only from some, not from all people that have done it.

This is the sort of thing that was concerning me, but so far I haven't been able to track down any firm evidence that there is any problem nor any tangible suggestion what the problem might be.

[project 112]

i asked this question on another forum some time ago and was told in no uncertain terms not to use copper as it will crack due to vibration on the flanges that you have to form to fit couplings for filters, pumps etc. how true this is i would,nt like to say but i suppose if your fitting new pipes anyway it will be as easy to fit kunifer as use copper even if its only for your own peace of mind.saying that i,ve piped all my brakes with copper!!

[GreenV8S]

project 112 said:

i asked this question on another forum some time ago and was told in no uncertain terms not to use copper as it will crack due to vibration on the flanges that you have to form to fit couplings for filters, pumps etc. how true this is i would,nt like to say but i suppose if your fitting new pipes anyway it will be as easy to fit kunifer as use copper even if its only for your own peace of mind.saying that i,ve piped all my brakes with copper!!

That would seem to be due to work hardening around the presumed swaged ends? Luckily in my case that wouldn't be an issue.

Edited by GreenV8S on Tuesday 12th May 01:18

[Pigeon]

Lister-Petter A range diesel engines have an external oil pipe made of copper. It is terminated by standard plumbing methods and does not fail from vibration. And you don't know what things failing from vibration is all about until you try bolting things to one of those engines