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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
 
It stays around 70 hot or cold
 
Compare it with another gauge first. Should be noticeable drop in pressure after hot.
 
What weight oil?

I went from a 20w50w to 10w30w and psi dropped quite a bit. I didn't like the high pressure all the time.
 
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.
 
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.
 
Change to a standard oil pump, no need for that much pressure.
 
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.
 
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.
 
Thanks to all who responded. Good info to ponder. This will help me test some things.You fellas are awesome. Thanks, Bob.....
 
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 :)
 
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 ??
 
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 :)
 
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.
 
There has got to be a reason I no longer use 80 psi gauges. Could it be oil all over the carpet.
 
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.
 
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
 
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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