The 'good old days' I jokingly referred to, was before fuel resistant 'rubber' pipes had been invented. The feed to the carb, was a small bore copper pipe wound like a large spring to accomodate the flexing of the engine. If it wasn't annealed regularly it simply broke. Mike.
I'd be surprised if there was enough movement on any pipes in a modern car to cause problems with copper. Remember it's used in house central heating systems where it moves a fair amount due to expansion etc.
Of course since kunifer is readily available, it makes sense to use that anyway.
It's vibration, coupled with age hardening, that makes it liable to crack. Although the movement caused by vibration is small, it's enough to accelerate the hardening to a point where it can crack. Thing is it's unpredictable. The pipe can look fine one day, and crack the next. The only way to be sure it doesn't, is to anneal it regularly. Held rigid, as it is in house central heating, age hardening, or movement due to heat, does not appear to be a problem, but if you've ever tried bending old copper pipe, you must have noticed how much harder and stiffer it appears, when compared to a similar new length. Mike.
Heh heh - new pipe is half hard as supplied and difficult to bend without using a mandrel bender. Old stuff was much easier - and on the odd occasion when I've re-used stuff and bent it, still easier than new. Think it had a thicker wall, too.
Possibly due to a slightly different manufacturing procedure. The way it's drawn can affect the final hardness. When I ripped out, and rerouted some old plumbing, I found it difficult to reuse the old stuff if it required bending, whereas the new bent comparitively easily. Pure copper does harden with age, and flexing. I've no doubt you'll find confirmation of that if you google. Mike.
Could be the old was Table X too.
But if you try bending new 15 or 22mm with a spring and without annealing, it will ripple on all but the most gentle of bends. Hence the need for a pukka pipe bender.
8 and 10mm is supplied soft and with thicker walls and may be bent gently with no tools - after all it comes in a roll.I'm not denying that. Just the circumstances under which it does work harden. And I don't think those conditions apply to a car where a steel pipe is replaced with copper - after all mild steel will also fracture if subjected to continuous flexing. Modern cars use a flexible 'rubber' pipe between steel and whatever to take up any movement.
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