[TheSilverBuick]

My learnings.

Take the oil from the oil pressure port off the oil pump. Use a relatively small line out to the regulator. I think I used 3/16th. Then have a relatively large line as the return from the regulator, I used 3/8th. Knowing what I know now, I'd port the oil right into the head at the rear oil galley plug. I was told a 90º wouldn't fit between the engine and firewall in a Firebird, but I'm convinced it will now that I have an engine in the car. I do not believe any dead headed pressure regulator (no return line) will work due to the pressure differential needed, but maybe playing with line sizes could get that to work.

I put a trimmed Buick high pressure spring in the oil pressure relief and dial the regulator down to cap out around 12-15psi with thick oil. It hovers around 7psi at hot idle. Main pressure on mine is now 55psi, and that was function of trimming, it was in excess of 70psi with an unmodified spring. I could put a few washers in the cap and up it some, but I'm comfortable with it at 55psi. I adjust the viscosity of the oil to meet a target of 35-40psi at cruising rpm.

Don't forget, if you are running an external line you have to close off the restrictor tube hole to the lash adjuster galley, or replace the restrictor tube with a piece of pipe. Some have simply soldered the hole closed, just make sure the solder job is good and won't come loose!

I'm running a straight pipe in place of the restrictor tube, but I think the next time I have the engine apart, I'm probably going to put a restrictor of some kind in as I think I'm getting too much oil up top. I'll probably measure the tube and shoot for half that area. Still will be significantly larger than stock. And technically the restriction is the center bearing journal of the camshaft, which I haven't measured for area.