Bleed valve adjustment

[HULK]

Can anyone tell me how many turns of the knob on a under bonnet bleed Valve need to be made to make the same boost pressure from carb base to carb top???????

[Brigsy]

No set rules on how many turns will bleed off mate, my only advice is half a turn at a time unless you want big boost!

[HULK]

Ok cool, just I had 14 psi at carb base, now piped it up to the carb top and it's only 10psi, turned the knob a bit at a time until it's been wound out a full turn and it's still 10 psi :scratch:

[Matt Cole]

do you mean 14psi at carb top? You would generally expect a pressure drop through the carb.

[HULK]

I measure boost at the carb base via the aei line. I have the cup mod and have simply piped the actuator from the side of the carb (14 psi) to the carb top which now gives (10psi).

Now I want to adjust the bleed valve to give me my 14 psi back, I have already adjusted the knob a full turn and nothing has changed. :scratch:

maybe I need a restrictor in the pipe from the valve to carb top but unsure of what size and how to make one??

[dangerous dave]

i'd pipe it back to the other line and keep an eye on what the engines seeing after the carb..

you might need to nip up a few pipes if your losing pressure like you have..

[HULK]

Sorted now. Put a restrictor in and all is well :)

[Markey Mark (BD)]

The reason you lost a few psi doing the cup mod is because the actuator lost the pressure on the back port which helps hold the wastegate shut, in theory its best to leave it how it was as you having to play with bleed valves just to bring the boost pressure back to where you started.