How much oil pressure is to much for a stock 350

[1977C20Silverado]

Why did you replace the original pump? There is no gain to having higher than recommended oil pressures. Only draw backs. The 10 psi/1000 rpm is a minimal rule of thumb. Check your pressure with a mechanical gauge (at operating temp) to see if there even is a problem.
Oil viscosity will also greatly affect your reading at lower temps, if you happened to have tried something different.

The oil pressure went from 30 to 60 to 5 within a minute or 2. Then later on it would start at 30 then go down to 5 until the motor died.

 

[andybflo]

The oil pressure went from 30 to 60 to 5 within a minute or 2. Then later on it would start at 30 then go down to 5 until the motor died.

I'll echo a few comments on here, and give you my advice...

Sid, a few comments back said over 60 is bad. Stone cold, for a few minutes, 60 is OK. He's right though, you hold that on a Gen1 SB, you'll start wearing bearings. Cold, with decent tolerances, on 10/30, 40-60PSI for startup is good.

Warm? Idle? Over 5psi. GM's idiot lights turned on around 3. The better indicator is if it snaps up quickly when you hit the gas. That's the key. I had a 355 in my Impala for a few seasons while I was hunting down some rare 409 parts at the time (they're more avaliable now), and she'd idle sub-10, but pull that magical (and mentioned) 10 psi per thousand all day. Sold it to a friend, and it's been running fine for years, other than the pretty regular SBC oil leaks.

Regarding the factory gauge, yes. 80s electric gauges are pretty terrible. I'll give you a personal story. When I did my LS Swap, hit the key, fired up, and I had oil pressure. Good pressure. When she warmed up, hit the 30/35 PSI range, it began bouncing like crazy. 5 to 50 PSI range, faster than you could see. Of course killed the motor, and thought of the million ways I screwed up putting a motor together I've assembled a hundred times, but somehow broke on my own car....

Know what it was? There's a copper pad on the gauge that the needle "floats" on, after 40 years, it floated around there forever. Wore the traces off. I verified with an auto meter mechanical gauge that pressure was steady, checked resistance off the sending unit that it was constant, and the gauge was at fault. Next time the dash is apart, I'll replace that gauge, and move on... I just ignore it now.

If you're truly worried, get a mechanical. Run it parallel for a bit until you're comfortable the "range" is OK. Then unplug it, and sleep well...

 

[Craig Nedrow]

I say, rejoice, that showed me that main, and rod bearings, cam bearings are good, live long and prosper type engine.

 

[MikeB]

My stock 350 TBI runs about 60 on the factory gauge at highway speeds. It'll idle down to about 35.

That's perfectly fine. I suspect the OP's engine will do the same.

I've always been happy with 45 at highway speeds and and 15-20 at idle in gear. And that's about 60 or so on cold start-up.

Oil weight will make a difference. If too much pressure is freaking you out, try 5W30 or 5W20.

 

[JBswth]

Sounds OK to me. If your oil pressure was, say 80 PSI, you might have excessive oil consumption, but your's looks normal for a good tight engine.

James

 

[mtbadbob]

That's perfectly fine. I suspect the OP's engine will do the same.

I've always been happy with 45 at highway speeds and and 15-20 at idle in gear. And that's about 60 or so on cold start-up.

Oil weight will make a difference. If too much pressure is freaking you out, try 5W30 or 5W20.

I don't think my gauge is 100% accurate either. It acts like there's an electronic glitch as it'll jump up and almost peg out at 60 psi, and it looks like something is causing the jump. Maybe I'll get it figured out!

 

[Fastduramax]

High volume and or high pressure oil pumps will always give you higher oil pressure with rod and main bearing clearances reasonably within spec, good tight clearances are much more important than the pump choice but not saying go with a cheap ass pump either... Generally .002" to .004" in a SBC/BBC is acceptable and converts to good OP, as any red blooded male would say the tighter the better, I have set up a couple 383's @ .0015 and they run massive oil pressure ! High oil pressure low blood pressure, live long and prosper Spock...