fork

And the thing I don't understand is on a holley 4 bbl, the accelerator pump is te only part of the carb that has nothing to do with vaccum. one side of the pump fills up with fuel and when you hit the throttle a arm pushes on the diaphram and pushes fuel thruogh the squirters. Thats why if a car isn't running and you hit the gas fuel will come out of te squirters but the not the boosters.

In conclusion, I don't know why the hell they need a vaccum line

Bone1

on a holley 4150/4160 you can tune the pump shot with the cam and the adjusting screw.

Also depends if your using a 35cc pump of a 50cc Reo pump. But most SBC don't need the 50cc unless it is a 406 SBC witha 300 cam.

Fuel is SUCKED out of the boosters due to the increased velocity due to the shape. The low pressure area creates a vacuum and fuel flows.

Sadly most don't know that when street driving a Holley, most of the fuel comes from the idle/part idle circuts and tuning the jets does very little for streetability.

chinoy

Break it down.
The first part is obvioully related to the squirter circuit.
Behind this we have the return line. With the second part of the gizmo.
There is a brass piston with an O-Ring that connects to the carb body.
THis is the bit that controls the return line fuel flow.

chinoy

DOes the fuel adjustment screw on a carb like this work diffirent from an air screw on a bike carb. Or are they both the same.
On a carb when you screw it in it gets rich cause less air is going in.
On this it seems when you screw it in less gas is going in. (Yeah I know that why they call it a fuel screw and not an air scre). But nobody has been able to tell me what screw this Mikuni carb uses.
Any sites / links / Articles on carbs worth reading up. Not much info on Mikuni carbs on gogole.

chinoy

Its a fuel screw checked it out with the colore tune.
Before I get abused for talking carbs. Wanted to avoid making a fresh post so Ill just throw my stupid quesstions in here.

Another question.

What diffirence does it make wether the vacum line is taped off before the buterfly or after.
Im asuming a vacum line taped off before the buterfly will have a weaker signal and signal will only grow as the throtel is opened.
Where as a vacum line taken below the throtel will have a stronger signal which will get weaker as the throtel opens am I right ?

Bone1

port vs. manifold vacuum signal...........depends on how the dist. is setup for the timing curve.