We're running a Holley Red Pump feeding 2 44mm Mikunis at about 4psi, which seems about right.
The biggest problem that we've had is supply to the pump---we ended up using 10mm tube from tank to pump to fix the problem.
Just remember, if you've got too much pressure drop, the fuel will vaporise in nothing flat, even in moderate temperatures.

I'm using twin 40 Dellorto's, a Holley Red pump and external Holley low pressure regulator set at about 2.5 psi. For a while I ran it between 3 - 4 psi, it ran pretty decent. But when I backed the fuel pressure off to 2.5, I noticed an increase in power, so I think 2.5 is a good pressure for Weber/Delloroto's...of course it depends on your jetting too. You can cheat rich jets by backing the fuel pressure off a little more, or run a little more pressure if you're running lean.

are you serious or are you talking bout putting a set of vice grips on the line?

you like running rich????

that sounds a bit odd to me

You dont have to run a regulator. I have a large Weber down draught on my Ford ute and an electric fuel pump that pushes about 7psi. It runs a little rich ofcourse but I have no drama with too much pressure, actually has a nice pop pop sound when you back off the go pedal or change gears.

If you cant afford a regulator then you can make a nice simple one that is effective and will cost you very little.

Simon

not on a downdraught weber (32/36 ect)

depends if you go for an elec pump or standard pump obviously, cause if elec pump has over 5psi then yes

with my 40mm webers i am running 2psi i think or maybe 2.5psi

got told the mech fuel pumps run anywhere bettween 2psi to 5psi, depending on throttle ,so when at max (5psi)throttle this could knock the needles in your carbs of thier seats

ive read up on sites that you should run a pressure regulater when running a webber carb. is this true? what are you guys running with your webbers?

many thanks
nicholas