Engine oil PSI

O'l geezer

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modified 440, 30 over, new cam, new flat tappit hydraulic lifters. At idle 950 rpm psi is 70. Is this type of engine need this high of psi ?
I have an adjustable pressure by pass valve but have not installed it yet. Any ideas ?
Thanks
Bob
 

Cranky

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For a lot of years I used 20-50 but stopped that 30 years ago or so....now it's 15-40. The adjustable valve will do what you want but so will a different bypass spring.
 

wagonman

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IMO you dont need that high pressure. Takes HP to turn the pump and stresses the shaft, gear and bushing. I run the standard Melling pump with a Black high pressure spring. 25 psi hot at idle 60 at cruise with 20-50. Race engine yes but 70 @ idle is to much for a cruiser.
 

R413

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Change to a standard oil pump, no need for that much pressure.
 

stage3

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i use the adj regulator from milodon with a melling H volume pump, i had to cut off 2 coils on the spring to get the oil pressure down to 55 psi at idle. now it has a good range of pressure to adjust in, and i also use 20-50 VR1 oil.
 

justcruisin

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If you have 70 psi at idle hot or cold you must have some fairly tight bearing clearances. I run a 440, solid flat tappet with 0.0025"- 0.0027" clearance rods and mains, 10W40, it has 70 psi cold idle but drops to 35psi hot. That is with an HV pump, if I swap out the spring from my original standard pump from the HP engine the cold idle drops to 55 psi.
 

O'l geezer

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Thanks to all who responded. Good info to ponder. This will help me test some things.You fellas are awesome. Thanks, Bob.....
 

khryslerkid

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Thanks to all who responded. Good info to ponder. This will help me test some things.You fellas are awesome. Thanks, Bob.....

You're welcome you O'l geezer.
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Stop in anytime :)
 

O'l geezer

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I did some checking and found out the psi at start up cold was 70-75 psi. Drove around for a half hour and it dropped to between 25 & 50 at idle, went to 70 when fever it up. Is that too high at cold start up ??
 

khryslerkid

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I did some checking and found out the psi at start up cold was 70-75 psi. Drove around for a half hour and it dropped to between 25 & 50 at idle, went to 70 when fever it up. Is that too high at cold start up ??

My 440 goes to 75-80 when cold. I just keep my foot out of it until it reaches operating temperature. It will do like yours, 70 or more when I punch it. Idles 30 or so.

You should have seen it when I had 20w50w in it! I use 10w30w now. Much better :)
 

PlymCrazy

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70-75psi cold and idling in my 383. Drops to 20-25psi idling when warm. Blip the throttle when warm it jumps to 40psi or so. That’s with 20w50 in it.
 

mopar 3 B

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There has got to be a reason I no longer use 80 psi gauges. Could it be oil all over the carpet.
 

AR67GTX

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I did some checking and found out the psi at start up cold was 70-75 psi. Drove around for a half hour and it dropped to between 25 & 50 at idle, went to 70 when fever it up. Is that too high at cold start up ??
That should be fine. I try to use an oil weight that will give me at least 20 psi at hot idle. Rotella 15W40 has been doing a pretty good job of that In most cases.
 

biomedtechguy

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Rotella 15W40
I've seen Rotella mentioned a lot in old school high performance engines as a really good but reasonably priced and readily available oil. Can you or anyone comment? I will only ask and not reply so as to not hijack. Thanks
 

AR67GTX

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I've seen Rotella mentioned a lot in old school high performance engines as a really good but reasonably priced and readily available oil. Can you or anyone comment? I will only ask and not reply so as to not hijack. Thanks

First admission - I’m also a long time C2 Vette owner and probably hopelessly corrupted by the C2 Corvette Forum and many on it use Rotella. But yes, a lot of old muscle and classic car owners do use and recommend Rotella, especially for flat tappet cam engines. I’ve been running it in my old cars for about 10 - 12 years except for in one motor I had custom built and the builder recommended Joe Gibbs HR oil. But it’s well broken in now and I’ll probably switch it to Rotella the next change. I’ve also seen a big following for Valvoline Racing oil too although Rotella no doubt has the cost advantage.
 

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