got it confirmed I have the wrong fuel tank from tiger if I want to go with throttle bodies instead of carbs.
apparently I can buy something that will correct the problem, does anyone know what this is?

thanks

[Edited on 7/4/08 by jimbona2]

you will need a swirl pot.available from loads of places cbs,denon tweeks etc.just fits in fuel line

isnt the only difference a fuel rail return to the tank, cant you get one wlded/brazed in?

You also need a two way breather, otherwise the air will get drawn in to replace the fuel as it leaves the tank, but when the fuel is returned, it will not be able to push any air out and the tank will pressurize.
I know because I,ve done it!

An injection tank should have a sump as well as the return to prevent air being drawn into the system during hard cornering/acceleration/braking. You can make up for a lack of sump by using a swirl pot. You feed the swirl pot with a low pressure pump from the tank, and then the outlet of the pot feeds the high pressure pump.

Carbs do not need this as they have the float chamber full of fuel to maintain supply to the jets if the pump draws air.

Some have got away without either a sump or swirl pot, and this will be OK as long as your tank remains relatively full. You will have probelms during high g manouvres with a low level in the tank without.

My last Westfield had an injection engine with a non-injection tank (single outlet on bottom, breather on top), and with no swirl pot. It worked okay apart from on track days - I'd get fuel starvation at anything less than 1/3 tank full.

The fuel return pipe was plumbed all the way back to the tank outlet, where it was tee'd into the supply line on the tank outlet.

Related question - is a low pressure pump like a red-top happy to run dry for extended periods? I'm considering increasing my tank capacity by fitting an oversized swirl pot. When the main tank runs dry will the facet be happy scavenging fumes for half an hour?

Gary

just had a word with scolar engines and they said if you dont have a fuel return the fuel can overheat. or at least there's a chance that might happen.
can get around this, anyone got any experience with this? what would I need to buy for my carb fuel tank to get it setup for TBs?

thanks

this is what I have so far, does anyone have photos of the bits I need fittered. Just to get an idea of how much work is involved.
many thanks
Rescued attachment pump1.JPG

pic2
Rescued attachment pump2.JPG

pic3
Rescued attachment pump3.JPG

First thing, is the pipe at the top of your tank piped to the bottom of the tank inside?
If not your pump will not draw fuel.
Second, why is your pump higher than the tank?
It will work better level or below the bottom of the tank and probably last longer. Some fuel pumps even use the fuel to keep it cool so if yours is running on air, it may burn out.

ok i can move the pump below the chassis bar is currently sits above so its in level, or slightly below the fuel tank.

not sure what you mean about the piped inside the tank so probably not although this was fittered before my time. i'll have a look inside the tank (although I dont know how) but what am I looking for?

[Edited on 11/4/08 by jimbona2]

If you do not have a pipe that reaches the bottom of the tank, then the fuel pump will just be sucking air.

ok thats cool. any good lateral thinkers out there that can hint how I can look in the tank? last time I looked its not easy to see whats in it.

It looks like you have connected you pump to either the breather pipe or return of the tank.
There should be another outlet on the tank low level, if not, you have problems.

Here is a link to a fuel tank. you can see the outlet in the swirl pot, a return pipe and breather on top of the tank (oppposite end to filler neck).
FUEL TANK

this is taken from a tiger avon build site, are these the bits I need?
Just trying to get an idea of what work is involved as that may very well determine whether I go carbs or TBs.

(hope using this photo is okay, if not u2u me and i will remove it)
Rescued attachment pic30.jpg

if I had the correct fuel tank would it be simplier? i.e. i wouldnt need to worry about the swirl pot, red top etc..?
is it better just to buy the correct fuel tank?
thanks,

You have connected the fuel line to the correct place on the Tiger tank as it does go to the bottom of the tank and the tank should already have a breather pipe. Your problem is the return and the fact that the carb tank is not baffled (which the Tiger Injection tank is). If the tank has not been used the easiest way would be to get somebody (Tiger?) to weld a return into the side of the tank or if you ordered an injection tank from them ask them to change it as it does cost more.
Another possibility is to get an 8mm screw on tank flang and put that in the tank near the level sender or use a Land Rover fuel pump which has the feed and return connections on it and use that along with it's own sender in place of the ETB sender, although I wouldn't swear that it will fit.