Board logo

Trivial fuel pipe question.
David Jenkins - 29/1/08 at 12:53 PM

I'm busy sorting out the layout of the fuel pipes for my bike carbs, and have come up with a 'cunning plan'. However, it's dependent on an assumption that I'll try out on you lot.

The 4 carbs come in 2 pairs, with fuel pipes between each pair (1--2, 3--4).

Ideally I bring 2 equal length pipes down from the connections, into a T-piece, then 1 pipe to the regulator.

However, it would be easier if I put a very short pipe on the first connection, then a much longer one to the other. I'm talking about 3" to the first one, 9" to the second.

Am I right in assuming that this won't make any difference, as long as the capacity of the pump, pipework and regulator can meet the demand for fuel?

David Rescued attachment pipe1.JPG
Rescued attachment pipe1.JPG


Mr Whippy - 29/1/08 at 12:56 PM

think of a injection fuel rail, fuel goes into the end.

so long as the feed pipes have a large bore you should have no problems, but I think it will look pants


ditchlewis - 29/1/08 at 12:57 PM

that looks like my twin forty fives. the pipe comes from the pump, first to a t piece conection that feeds the first carb then on to the second carb.

ditch

[Edited on 29/1/08 by ditchlewis]


Agriv8 - 29/1/08 at 01:03 PM

Rover V8's run all the injectors in series .

Ie fuel pump resure in at one end and regulator out at the other.

Regards

Agriv8


BenB - 29/1/08 at 01:06 PM

The pressure within the system should be the same so it's no problems doing it either way.


RazMan - 29/1/08 at 01:11 PM

With carbs surely it is more about flow than pressure - as long as you have enough flow then you should get the same at each carb regardless of plumbing. However if flow is restricted in some way (pinched pipe or knackered pump) then the carb furthest down the line will be starved first.


[Edited on 29-1-08 by RazMan]


Rosco - 29/1/08 at 01:11 PM

There's a pressure drop associated with any length of pipe, so you will get a slightly difference in fuel pressure. I would have thought this would be insignificant on such short runs but you could help yourself by using a larger diameter line and/or by making sure that the runs, especially the longer runs, are a straight as possible.


Phil.J - 29/1/08 at 03:18 PM

With carbs you have a buffer in the fuel supply system in the form of the float chamber which can handle small variations in pressure.
As long as the fuel line can flow sufficient fuel for your maximum needs then either layout will be fine.


David Jenkins - 29/1/08 at 06:58 PM

That's what I thought - thanks!

BTW: The pipework won't be seen very easily, so I'm not too worried about looks...