[BillB]

I have a 67 with a 454...The engine has an 8 quart oil pan with a Melling hi-flow oil pump. The engine has approximately 2500 miles on a complete new build. When I start the car cold, it generates 70 to 80 psi oil pressure. As it warms, it drops to between 40 and 45 psi. When the engine is fully warmed up and operating temp, it cruises at highway speeds and maintains 40 psi..at an idle, it drops to about 10 psi. Makes me nervous. $$$$ Is this normal and common with big blocks? A buddy of mine told me that big blocks are known for this. True?

 

[Tom Mobley]

If it's a high volume, high pressure oil pump these numbers are low. If you're using the 30 year old factory gauge on it, put a new mechanical gauge on it and try it out before getting worked up.

Tom

 

[Wally]

All it needs to be safe is 10lbs per 1000 rpm. This is a GM standard. My 454 in my SS454 has somewhere between 10 and 30 using the factory gauge when fully warmed up. I also run Mobil 1 oil in the beast which reads a little lower than regular oil.

Most of the race small blocks I did had 25 at idle, 60 to 80 at 7000 plus.

I can't figure out why there is this thing about high pressure and the other deal about high volume. The sbc and rat motors have one of the best oiling systems out of the box, the stock pumps are fine for most applications.

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Wally
Gold #67
67 malibu

 

[Gene Chas]

Not that I'm a BBC expert, but I've never seen one idle that low. What's your idle spped. If you say it's 600, well then , maybe it's ok. Most pumps I've used on new motors hold 30-40 psi at idle. New engines are seemingly going to low pressure. My Aurora ( well, it's the banks) idles at 9-10 psi hot. Freaked me out when I saw it. Went right to the dealer and they said it's normal. Something about a variable pressure pump. Huh? And this is supposed to be a hi perf Northstar engine. Go figure. Frictional losses I guess.

 

[72Elky]

Although I have a small block, I'd still say those numbers are a little low. Mine runs at about 20-40 during idle, and 60-80 at about 4000-5000.

 

[godsend]

Its too low, you wear things dowm... Take your engine apart and change your bearings...
Its only a tip, when things happen it goes so fast. And you are going to eperience som bad things with so low pressure...

 

[Wally]

To low, I don't think so. A Detroit diesel, 22 to 1 compression, blower and turbo, at idle it has 8 pounds of oil pressure, that is normal pressure, 2 pounds per cylinder. Still think it's to low?

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Wally
Gold #67
67 malibu

 

[BillK]

Bill,
I don't think the pressure will hurt anything as long as it comes right up. I mainly wanted to enclose this link to Mellings web site. It has some very interesting and informative articles about oil pumps and oil pressure.
http://www.melling.com/
Hope it helps dispel some myths.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

 

[godsend]

I suppose your min bearings or rod bearings are worn out, and yes you still got the lubrication there with a lot more oil than before but without the pressure you dont get it up in the motor, tho lifter, and the rest of the valvetrain. Mayby you got grooved bearings or something, change them to stantard if you dont spend all your engines life on the track exeeding 6000 rpm or so...

 

[SSRat]

Bill,
I live just down the street from lunati and they say factory big blocks are known for this, it should be ok. This is reason for old tech. of cross drilling crank to increase oil flow but now they have only partial drill hole, it creates a vacume and they install groved bearings to help. One other thing they also say to plug bypass valve. chevy bypass comes off it seat at around 16psi and about 70% of the oil misses the filter so on there engines its pluged and all oil must go through filter.

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[Gus]

My motor has a Mellings high volume oil pump. At normal operating temps, the pressure is 40 at idle and at 60 when I'm cruising.