Engine oil PSI

[O'l geezer]

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

 

[Geoff 2]

Hot or cold?

 

[O'l geezer]

It stays around 70 hot or cold

 

[PlymCrazy]

Compare it with another gauge first. Should be noticeable drop in pressure after hot.

 

[RemCharger]

I would be happy with it.

 

[khryslerkid]

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.

 

[Cranky]

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]

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]

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

 

[stage3]

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]

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]

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

 

[khryslerkid]

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.

Stop in anytime

 

[O'l geezer]

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]

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]

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]

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

 

[AR67GTX]

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]

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]

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.