I bought a dead 1991 S10 blazer 4.3L 4x4 with seized motor (oil pump failure @ 160k). I put in a used motor from a 1990 4.3L 2wd Astrovan (60k miles). I used the oil pan from the blazer, but I used the astrovan's oil pump, and used the blazer's pickup tube (astrovan's pickup tube didnt work with blazer's oil pan). Its installed and running, at 40psi oil pressure on the dash oil gauge.
Now, as you know, the 1991 blazer has remote oil filter lines. I started thinking, does this setup require more oil pressure to run correctly? Is 40psi good enough? What do these 4.3L TBI S10 blazers usually run at? Afterwords, someone told me "you can't mix oil pumps and oil pickup tubes, they are one piece" ?? I tapped the oil pickup tube into the oil pump, with the tube coated with silicone where it meets the oil pump... Hopefully this holds together??
Any thoughts?

 

I generally like to put a tack weld on the oil pump to pickup, but, chevy just press-fit them, and it works pretty good, so, if it was kinda tough going in, you should be fine.

If you are getting 40 PSI at idle, you have plenty of pressure. After all, the sending unit for the gauge is on the motor, so that is showing pressure IN the motor. Anything over 10 psi at idle, is considered "acceptable"...... for what that's worth......

 

I looked closer at it, and the oil pressure is usualy around 30psi, I would guess, on the gauge. Hits around 40 with some throttle, so I wont worry about it!
Thanks for the reply