oil pressure -- how much ?! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71sub · 12-01-2003, 02:07 PM

My 71 truck w/ an '85 350 shows ~ 60-70psi oil pressure when operating ~ 2k RPM, using a Sun oil gauge.

My 71 sub with a OEM 350 shows ~ 30-35psi oil pressure when operating ~ 2k RPM, using an Autometer oil gauge.

Both vehicles have the same type and amount of oil. Which one is right / wrong ? Will a high volume oil pump change the oil pressure ?

Ev

*67Fleetsidedream* · 12-01-2003, 02:12 PM

What is the operateing temps? Oils change viscosities when the get warm....My truck when worming up will go to 70+ psi.....But at operating temp and 3k rpms it is 45 psi.....

junkyardjohn · 12-01-2003, 02:22 PM

A GOOD RULE OF THUMB IS 10PSI FOR EVERY 1000 RPMS OF ENGINE SPEED, & YES A HIGH VOLUME PUMP WILL INCREASE YOUR OIL PRESSURE SOME, BUT NOT NEARLY AS MUCH AS A HIGH PRESSURE PUMP.
RUNNING 30-35PSI AT 2OOO RPMS IS NOT INDACATIVE OF ANY PROBLEM HOWEVER.

JOHN

tom hand · 12-01-2003, 02:34 PM

A bone stock motor will be 20-25 at idle, 40-50 at highway speeds, with the motor at operating tempature. You can get oil pumps with differant springs to put the pressure about anywhere you want, but too much oil pressure has no advantage...wastes horsepower, is rough on distribitor gears, and will make the rear seal leak. You need to use the same gauge on both motors to compare....ethier way both motors sound fine

71sub · 12-01-2003, 03:20 PM

Great !!

The operation temp on the Sub is ~ 160 and Truck ~ 180.

I like the 10psi / 1k rpm rule -- thanks.

So, the 60psi on my truck is probably the PO changing the OEM oil pump config ?

Ev

Longhorn Man · 12-02-2003, 01:39 AM

the one with low oil pressure could be getting worn. Loose bearings will do that.
Mine has real crappy oil pressure anymore. It is a constant reminder to check my oil a bit more often.

VTKidder · 12-02-2003, 10:12 AM

Neither really seems like a problem waiting to happen. As Andy said, one engine is 14 years older than the other, and things do wear out. I wouldn't run out and get a new small block because you're running 30psi though. Just check the oil and run it.

12-01-2003, 02:07 PM	#1
71sub Registered User Join Date: May 2002 Location: Stockton, CA Posts: 169	oil pressure -- how much ?! My 71 truck w/ an '85 350 shows ~ 60-70psi oil pressure when operating ~ 2k RPM, using a Sun oil gauge. My 71 sub with a OEM 350 shows ~ 30-35psi oil pressure when operating ~ 2k RPM, using an Autometer oil gauge. Both vehicles have the same type and amount of oil. Which one is right / wrong ? Will a high volume oil pump change the oil pressure ? Ev __________________ 71 C/10 : 350 / 700r4 ; Ford 9" posi 3.50 with 31x10.5 rear tires, single drive shaft, C-notch, 2.5" drop spindles, keyless entry 71 Suburban 350/350 -- caddy tail lights, keyless entry, late model seats, billet Autometer instrument cluster 70 Ford Torino -- 351W (balanced & blueprinted ), C4, VDO gauges

12-01-2003, 02:22 PM	#3
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,425	A GOOD RULE OF THUMB IS 10PSI FOR EVERY 1000 RPMS OF ENGINE SPEED, & YES A HIGH VOLUME PUMP WILL INCREASE YOUR OIL PRESSURE SOME, BUT NOT NEARLY AS MUCH AS A HIGH PRESSURE PUMP. RUNNING 30-35PSI AT 2OOO RPMS IS NOT INDACATIVE OF ANY PROBLEM HOWEVER. JOHN __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST

12-01-2003, 02:34 PM	#4
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	A bone stock motor will be 20-25 at idle, 40-50 at highway speeds, with the motor at operating tempature. You can get oil pumps with differant springs to put the pressure about anywhere you want, but too much oil pressure has no advantage...wastes horsepower, is rough on distribitor gears, and will make the rear seal leak. You need to use the same gauge on both motors to compare....ethier way both motors sound fine __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

12-01-2003, 03:20 PM	#5
71sub Registered User Join Date: May 2002 Location: Stockton, CA Posts: 169	Great !! The operation temp on the Sub is ~ 160 and Truck ~ 180. I like the 10psi / 1k rpm rule -- thanks. So, the 60psi on my truck is probably the PO changing the OEM oil pump config ? Ev __________________ 71 C/10 : 350 / 700r4 ; Ford 9" posi 3.50 with 31x10.5 rear tires, single drive shaft, C-notch, 2.5" drop spindles, keyless entry 71 Suburban 350/350 -- caddy tail lights, keyless entry, late model seats, billet Autometer instrument cluster 70 Ford Torino -- 351W (balanced & blueprinted ), C4, VDO gauges

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12-01-2003, 02:12 PM	#2
67Fleetsidedream Wiseass secured himself a BAN Join Date: Nov 2000 Location: MOON!!! Posts: 2,282	What is the operateing temps? Oils change viscosities when the get warm....My truck when worming up will go to 70+ psi.....But at operating temp and 3k rpms it is 45 psi.....

12-02-2003, 01:39 AM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	the one with low oil pressure could be getting worn. Loose bearings will do that. Mine has real crappy oil pressure anymore. It is a constant reminder to check my oil a bit more often.

12-02-2003, 10:12 AM	#7
VTKidder Registered User Join Date: May 2003 Location: Vermont Posts: 996	Neither really seems like a problem waiting to happen. As Andy said, one engine is 14 years older than the other, and things do wear out. I wouldn't run out and get a new small block because you're running 30psi though. Just check the oil and run it.



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