Gt6 mk3 tank to carb, plumbers copper??

[gt6j]

Hello I have had a search but couldn’t find definitive, am I ok to use screwfixs 8mm copper for fuel line from tank to pump on gt6mk3? Pulling old out to change brake lines and noticed it’s a hardish plastic and all rubber from tank to the hardish plastic which starts around the rear passenger wheel. Would leave it but looks undersized to me. Thankyou

Edited April 27 by gt6j
Typo

[Pete Lewis]

plastic based fuel lines were common in the late 70s for many  manufacturers

if the bore is around 5/16 " its fine 

1/4" and 5/16" seems to be commonly used across the range and various model years

the long length of old rubber may be a bigger problem with old and fake fuel hose being sold 

Pete

 

[Ian Foster]

Tank to fuel pump should be 5/16" (8mm). 1/4" (6.3mm) is standard from pump to carbs.

Ian

[micklewis]

automotive 8mm /5/16" copper will have a thicker wall  than heating 

[dougbgt6]

As standard there's a rubber joint in the passenger side rear wheel arch. Oddly my pipe from tank to wheel arch is 1/4" and 5/16" thereafter. I used to worry about this, but it's never been a problem and I'm loathed to start messing about with the joint in the tank to replace the pipe. 

I vaguely recall that copper fuel lines are illegal in Australia, don't know why, not as strong as steel? So don't be driving to Oz! 

Doug

Edited April 27 by dougbgt6

[micklewis]

could run the fuel line in 8mm nylon  ( same as truck air brake piping )  no different to any modern ,

while your re plumping add a inline fuel filter between the tank and the fuel line  keeps the line clear 

[gt6j]

Thankyou something telling me to leave it alone then if plastic used?? Lots of worried words about copper and rubber online wish I hadn’t googled it. Will double check rubber bits 

[Unkel Kunkel]

I think a possible issue with copper would be work hardening and brittleness if there is flexing of the pipe.
How much of a  potential problem this is  I don’t know, and whether it could be addressed be by careful  installation with regard to support / fixings for the pipe?

[Pete Lewis]

sold by many but club shop sell gates barricade fuel hose 

far better than the fake stuff sold 

Pete

 

[Morgana]

Copper work hardening is a major issue, to the extent that it's a failure in many vehicle test codes (I don't know about the MOT specifically). Perhaps that's only a giant no-no for brake lines which are under high pressure, and you might be OK for low-pressure carburettor feed pipes as long as it's very well supported to avoid vibration. However, heating pipe at 8mm is not the same as fuel pipe at 5/16". I'd go to a reputable motor supplier and get 5/16" cupro-nickel ('kunifer'). All the malleability of copper for easy forming, but without the work-hardening, crack and then a fuel fire. I think copper needed twice as many supports as steel, which gives you some idea of the different strengths and resistance to vibration damage. Once they realised the troubles with copper, it was no longer approved and then cupro-nickel came along. From your photographs it doesn't look like there are many supports at all. Perhaps modern-style nylon would be the best like-for-like as mentioned above.

If you use cupro-nickel, don't forget to put a bubble flare on the end where it joins any rubber hose (and yes, get kosher fuel hose from the club as Pete Lewis says). I don't mean a specific standard, but a half-formed double flare, just so there's a smooth bulge in the pipe at the end. Put the hose clip behind this bulge and then the rubber hose can't come off.