Just got my Z11 back from very reputable shop. $4K for a complete rebuild of the 350. It went in with low oil pressure and knocking. When I first got it back the oil pressure once warmed up would be 5 psi at idle/20 psi cruising. Took it back and they put the high pressure spring in the new oil pimp. Still getting 5-10 psi at idle/30 psi cruising.

Oil pressure in my 350 Suburban with 250,000 miles on it is 40 psi at idle/60 psi cruising.

What should good oil pressure be in a completely rebuilt Chevy 350 be? It has new crank, bearings, oil pump, pistons, rings, resized rods, valves, lifters, everything is new except can and timing.

 

Rule of thumb 10 PSI every 1000 RPM. There is a possibility that the shop left out one of the oil gallery plugs and there is an internal oil leak. This is a pretty common problem with rebuilt engines. Some shops, rather than fixing the problem, mask the problem by replacing the standard oil pump with a high volume one.

 

Is this with a mechanical or electric gauge? If electric, there's a possibility it could be a faulty switch or gauge.

 

Are these plugs accessible without pulling the engine?

 

May want to look at this
Possible Oil Pressure Leak Due to Missing Rear Oil Galley Plug - Chevy Forums at Chevy High Performance Magazine

 

I agree with the 10 lbs. per 1000 rpm thing, except at idle. You should be at least 20 lb. at idle, then 10 psi per 1000 after that. Both my SBC idle at 40psi and my BBC idles at 35 psi cold. They all drop a little once they warm up, except the 327, which holds regardless of temp.