What PSI perssure for a normally open lean out valve

The norm is a 60 jet at 50-60 psi but with most systems that means it opens on launch. The best thing is to use a 12 volt fuel solenoid on a timer so you can delay it opening if you have too much power on launch. This way you can open it .8 to 1.2 sec into the run. If you have. 8973 or a Grid then it has one built in timer that supplies a ground

 

NO valve

It really depends on when you want the jet to be open.

With a NO valve, I recommend you run some sort of check. It needs to be at least as high if not higher than your idle check. If you have no check, it's flowing all the time and will make your system leaner at idle. Obviously you will get some of that same affect if the check to the valve is lower than the idle check.

Another way to plumb it is behind the bv so it does not really work until stage or after WOT (depending on how your spool is set up). You will still need a check.

The more modern way to do it is with NC valves opened and closed with timers. Even if you don't want to do a timer, you can open the timer with air or electric from a WOT sensor and close it on the shift.