what is the optimum fuel pressure to run in a holley? I set up my mallory 140 with a return reg., and set it at just under 8psi. Is this to much? Is there an advantage to running as much fuel pressure as possible with out over coming the needle and seat?

Thanks Rich

I have my Comp140 set at 8 psi,feeding a 120 gph Carter mechanical,,,I might be a touch high,but I have had the carter mechanical doing alot of fluctuating lately. 7-8 psi is usually max for a Holley without over pressuring the needle valve.

All you need is enough to keep the carb bowl full. If you could do that with .5 psi, then all you'd need is ..... .5 psi. IMHO the lower the better. There's no point in running it on the ragged edge of causing excessive fuel level all the time.

Holleys typically have a large enough needle valve to where at least 500 HP worth of fuel can get through 2 of them at 5 psi. Unless you're running alot more HP than that, I'd suggest lowering it. Less chance of the unexpected that way.

Rich,
5 or 6 pounds is plenty of pressure, but the most important thing is how much pressure do you have during initial launch and in high gear during WOT. This is where fuel pressure is important,
as the fuel pump must overcome the inertia/weight of the fuel and keep the carburetor supplied at maximum rpm in high gear.

I like running 6 - 7 psi.

8 is too much IMO and may overcome the needle and seats intermittently making the engine go fat at idle or under light loads.

5 or less and you could go lean on the top end if fuel pressure drops a little at high RPM. A problem like this would be more likely if your fiuel pump and line is "just big enough", an overkill fuel system would probably not have a problem at 5 or even 4.