Making fuel lines is a little frustrating but ultimately satisfying. Frustrating because when you bend pipe you only get one shot at it. Any one bend in the wrong place or at the wrong angle means throwing that piece away because you can’t un-bend it. Satisfying because whilst you know that no one will ever appreciate the work it took, YOU know that no one noticing it means you got it right…
Putting pipe runs to one side for a minute, having managed to get all the engine cooling elements fabricated, sealed and holding water – I shifted my attention to the electricals and I have I *think* put the distributor into a position where it should be close enough to allow the engine to start, it can be adjusted once the engine is running. There are no ignition timing marks on these cars plus I have updated the internals of the distributor to be electronic (and not need the unreliable points) so it is now impossible to tell visually or otherwise when the high voltage surge would be sent to a spark plug.
The carburetors have been setup based on experience in what I will call a ‘default’ position which again should be close enough to allow the engine to breathe but will need adjustment for maximum power (coughs theatrically). I have adjusted all the throttle linkages so that both carburetors open together and adjusted all the linkages from the throttle pedal to the carburetors taking out the loose play. I also had the foresight to fabricate a solid pedal stop in order to prevent a heavy right foot bending the carburetor linkages but all of that is now in place and ready to go
So back to the title of this post – pipe runs, more specifically – fuel.
In early motoring history fuel was fed to the engine using gravity requiring the fuel tank to be above the engine, technology moved on and by the 1920’s cars commonly had a hand-operated pump on the dashboard which pressurised the fuel tank with air. (yes seriously) following pneumatic principles, the compressed air pushed the fuel out of the tank towards the engine. When you stop the engine there is a manually operated tap on the fuel tank to let the pressurised air out again. The fundamental flaw in that design is that you needed to rebuild the air pressure over a surprisingly short distance. One of the jobs of a riding mechanic was to operate that pump throughout the journey. Luckily Riley’s were always on the forefront of design and in the 30’s it was common to have an electric fuel pump mounted onto the bulkhead in the engine bay. Thank you Percy.
Where the pump is mounted is not an aesthetic decision – these pumps are not able to ‘suck’ fuel up to a great height and they also need to be close to the carburetors to keep the pipe run short.
In my car, there are not actually many places the pump can be mounted. Once a decision was made, I then had to work out how to route the copper pipe from the pump to the carburetors making sure it would not be in the way of any moving parts such as the gearbox linkage. I also have to factor in how the pipe from the fuel tank gets to the pump. 5/16 copper pipe doesn’t bend at acute angles so the shape of the pipe run also needs to consider those bend angles. Back to the first paragraph – get the angles wrong and you throw away the pipe. A challenge – I like it.
I first worked out how the pipe needs to route to get to the bulkhead, it had to go up and over the gearbox linkage but not obstruct the fuel mixture adjustment nut on the rear carburetor. Now I had to work out where the pump could sit giving me enough room for the inlet pipe and the outlet pipe. It was soon apparent that this was going to be a complex piece of pipe bending.
The picture below shows you just how complex it needed to be and the tool that pulls the pipe around a mandrel and into shape:
The full 360 degree bend (which was quite interesting to achieve!) is to allow the pipe to have some flexibility – the engine will move when it is running – the fuel pump is bolted to a non moving surface. If the pipe was rigid; over time the to and fro movement would cause a fracture in the pipe and the fuel pump would happily provide a pressurised spray of fuel all over a hot engine. This is something I am fairly keen to avoid.
In the picture below you can see the pump-to-carburettor pipe in its final position. I am rather proud to say this was achieved on my second attempt. The only reason had to reject the first try was because I wasnt paying sufficient attention and kinked one bend because the pipe fed into tool incorrectly. But I am rather pleased with only needing two tries. I suspect the experience gained restoring my Etype Jaguar (that blog is at www.connor.org.uk) which had a LOT of pipes that needed complex shaping, had given me sufficient knowledge to progress with confidence.
Out of the left side of the pump will be another pipe that will run straight down, back under the car along the inside of the chassis rail to the fuel tank – I have that excitement to look forward to another day – thats a 6 foot pipe to play with…