Guy's oil pressure is alot lower in new motor, what is to low?

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Oct 22, 2000 | 12:06 PM
  #1  
While driveing it will be up around 50 psi, but at ilde it is down to about 20 or so, I am running 10-30 oil, The motor has about 600 miles on it, my old 305 was always up around 50. So what is normal, I have a brand new gm 350.

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86Z28, GM 350, Jet perf Q-jet & chip Dual snorkel air cleaner, Edelbrock performer intake, Edelbrock headers, Edelbrock cat-back, Off road pipe, MSD 6AL, Accel Super Coil, Taylor Spiro-pro wires, Rapid fire plugs, Jet fan switch, World class t-5, Hurst Short Throw Shifter, Ram Flywheel, Center force dual friction clutch,Aluminum drive shaft, BW disc rear 3.45's & a posi, PBR calipers, Earls braided brake lines, Polygrapite bushings all the way around, poly tranny mount & torque arm mount, Hotchkis lower control arms & panhard rod, Rancho limiter straps, KYB struts & shocks, Gm Wonderbar, Edelbrock strut tower brace, SSM sub frame connectors, Jamex lowering springs, Carbon metallic brake pads, Crossed drilled rotors, Mobil 1 Tranny fluid & motor oil, GM syntheic rear end oil, K&N, Grant stering wheel, 1,200 watt system, Jet Black Paint, 91 Z28 rims, 92 wing, Tinted windows.
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Oct 22, 2000 | 01:12 PM
  #2  
depends on where you look or who you ask, but the most common pessure reading i see cited are 10 psi for ever 1000 rpm or 35psi at 2000rpm (i think, i never pulled my manuals to look it up) the factory gauge isn't known for being accurate, i'd check it with a mechanical gauge.

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-=ICON MOTORSPORTS=-
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Oct 22, 2000 | 01:27 PM
  #3  
Actually, the GM minimum requirements are EVEN LOWER: 7 psi @ idle and 20 psi @ 2,000 rpm are the MINIMUM requirements. As for the 10 psi per 1,000 rpm, remember that is for SUSTAINED RPMS. If you are going to run a sustained 6,000 rpm, then you should have at least 60 psi of oil pressur. But (on a typical street engine), 2,500-3,000 rpm is the normal sustained rpm, therefore you should have at least 25-30 psi for that sustained rpm. The occasional peak rpm of 5,000 rpm (such as when you pass a car) doesn't necessitate a minimum 50 psi of oil pressure.

Frankly, your oil pressure looks fine, though a bit on the low side @ idle for a new engine. 30 psi minimum (fully warmed @ idle) is genereally what I've seen on a new/rebuilt engine. So I would monitor it to see if it gets worst.

But I have to agree with ede's comment about the lack of accuracy on the dash gauges. Also, your sensor might be a little weak and is the most common reason for erratic oil pressure readings. I would try changing that first, if you haven't already. And 2 sensors (or guages) don't necessarily read the same, even if new.
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Oct 22, 2000 | 02:31 PM
  #4  
My oil psi usually hangs around 40-50 psi especially if I am driving. At idle, it is about 30-40psi unless the temps get around 220F, then it goes way low to about 20psi at idle... 40psi while driving even when that hot.

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock... all the suspension stuff... 9-bolt posi disk is in... K&N filter... 93 octane...

-=ICON Motorsports=-
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Oct 22, 2000 | 03:43 PM
  #5  
I have got around 6000-8000 miles on my 350 that i rebuilt and running 10/40w oil..... and it holds right at 60psi and even when engine is hot it still holds 50 or better...
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Oct 24, 2000 | 08:33 PM
  #6  
Does 5-30 and 10-30 have diffrent pressures? what about mobil one compared to regular oil, will it give diffrent readings?
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