I have a 1988 Cigarette Bullet that has Hardin Marine external water pickups thru the transom. I asked questions here on the board(previous screen name that I lost access to) as far as placement and consensus seemed to be for them to extend about 1/8” below the bottom of the boat. I put them about 3/16” below thinking it easier to take some off as opposed to adding some. My water temps are solid at about 160 but my water pressure shows about 5 on one side and 0 on the other. The motors are fresh, the sea pumps are new oem pumps, the circulation pumps are new, the oil coolers are new, and the exhaust is new Imco units so everything should be in good working condition. Any ideas why the water pressure is low? Thanks

Need to know more about the engines, are you only dumping exhaust water ? no intercooler or steam dumps.......pickups going directly to the sea pump.........The mods may be able to recover your old screen name

also need to know when you see those pressures. at idle or up and running?

The engines are basically stock 454 Mags. They are bored 0.030 over and are converted to hydraulic roller cams, and roller rockers but otherwise stock. The water pickups are connected to 1.25” i.d. hose and connected to the sea pumps. I do have a screen filter in-line just in case. Nothing else is dumping out with the exhaust.

Hope you added ball valves to that setup. If a hose pops off, you’ll have an incredible amount of water coming in fast - faster than you’d be able to pump out.

And what kind of screen filter? Unlike a outdrive’s slatted water inlets, transom mounted pick-ups can suck in some pretty big stuff (you’d be surprised). You really should have strainers inline that will catch debris while still allowing water to flow.

Where are you getting your pressure from? In-line? Blocks? Thermostat housing?

Water pressure at idle is 0-3psi in most cases. As long as you have water flow out the exhaust, it's fine.
The psi when running at various rpms is what is important.

As far as the pick up being below the hull, I'd make the leading edge even with the hull bottom, and angled to be deeper at the trailing edge