Ok, so i know i can adjust the carb and what not to lean it out.... but the car is running great just runs a little rich. It has the Racing beat intake manifold set up with the 4 bbl holley carb. With this kit you must install the Electronic fuel pump.... pressure regulator...ect. It is running 8psi through the gas lines could that be the cause of running rich? Thanks.

 

Your basic 4150 Holley carb likes 6 to 7 psi of fuel pressure...drop it to 7 and see what happens. You may end up having to change jets, though. I'm more used to Carter Thermoquads, Rochester Quadrajets, Tri-Powers and stock Nikki carbs, though. I'm basically regurgitating decades of reading Car Craft and their experiences tuning Holley's...

Let's see if any real Holley men-men are out there.

Mario III

 

How do i adjust the pressure its running through the lines? I haven't ever had to mess with fuel pressure before so just a quick idea and i should get it.

 

You mentioned fuel pressure regulator...if you've got more than just the basic Holley electric fuel pump, you must have one installed between the carb and the fuel pump. It should have instructions but usually it's just a matter of a screw with a slotted head secured by a set nut on the body of the regulator. Now, what pressure you're dialing in is another matter altogether if you don't have a gauge installed on the line leaving the FPR.

 

It does have the gauge and on some days it reads 8psi and others 9psi, to my knowledge there is a walboro 255 fuel pump installed. Would i tighten the nut to turn down the psi? I'm guessing i would do so while the car is running?