Combines l3 hydro pump

I can't see why you can't boost the pressure a bit if pump is half decent. Are you talking '79 and prior where you would of had to pull valve from port plate to tear it down and shim it or '80 and newer where it is screw adjustable to a certain point and may need shim if not enough adjustment. I hope my memory is right on that. Seams to me we did this a few times years ago.

It is an 1983 model. Where is the adjustment screw you are talking aboutIJ Thanks

OK I had to check manual to refresh some brain cells. This was not meant to be screw adjustable. The lock nut and screw are between the frame and valve on master solinoid (n1). A one inch wrench cracks the lock nut loose and screw is slotted. I did find some of them screws that were not bottomed so cracking the nut loose and then cranking in the slotted screw bumped my pressure as needed. If this does not do it for you you will have to remove lock nut with screw to get between spring and screw with a shim. Shim number is 71176962. Maybe this is where you shimmed allready. Even if it is give it another to see if pressure comes up. I really think if other headers were lifting fine the pump is OK and you only need a bit more pressure. Good luck