Jun 172012
 

The fuel and brake lines were other items that were to be replaced as a matter of course during the rebuild. I had intended to purchase lengths of piping and make the individual pipes myself. However the cost of decent pipe flaring tools, able to achieve consistently good joints, are considerably more than complete kits.

So I’d purchased a brake kit from Automec, a similar fuel line kit from Hutsons and a pipe bending tool. Both kits were supplied in copper rather than bundy or cunifer which is closer to the original look. So I’ll have to see how they look on the car and I may revert to fabricating my own in cunifer; an alloy of Copper (Cu), Nickel (Ni) and Iron (Fe).

More importantly, I subsequently found out that copper brake pipes are banned in countries like Australia and the US, where cunifer is the norm. Apparently the copper pipes are susceptible to work hardening over time which can lead to fracturing. The introduction of Nickel and Iron addresses this problem. I think more research is needed especially as it’s a safety issue.

Back to the pipes … the problem with the kits is that they are fabricated from coiled piping. In order to get neat, straight pipe runs they need to be straightened before forming into the correct shapes.

I found an article on an American car site with a rather over-engineered process for straightening coiled fuel pipes. I had a spare afternoon so I thought I’d give it a go. The main point is that the coiled fuel pipe should only be straightened/bent in the same plane as the direction of the original coil.

The first step is to lay the coiled pipes on a flat surface and uncoil them against a straight edge, therefore ensuring additional bends in other planes are not introduced. Once released, the pipes will spring back to some extent in the direction of the original coil so the pipes will now form an arc.

Trial run with the shorter engine bay 5/16″ fuel pipe

Long boot to engine bay 5/16″ fuel pipe

The second step involves deforming the pipes beyond a straight line so that this time, when they spring back, they (hopefully) return to a straight pipe. As it happens, the pipes need to be bent beyond the straight line to exactly the same radius as the arc of the now uncoiled pipe.

I used two pieces of old shelving and some 9mm cladding, the latter would act as channel down the centre of the form. I guess you could just use one board against a flat surface.

The radius of this arc is determined by the pipe thickness and the diameter of the original coil. Therefore, for a given pipe size from the same original coiled length, the arc radius will be the same regardless of pipe length.

The final step is bending the arced pipes over the form. Starting at one end, position the pipe arcing away from the form but in the same plane. Then bend the pipe around to produce a straight pipe when released. However be careful not to allow the pipes to rotate when doing the final step.

I thought the results were quite good for a pleasant afternoon spent taking a sledgehammer to crack a nut!

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