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Re: Oil Pressure vs High RPM's ?
[Re: Pacnorthcuda]
#948531
03/11/11 03:00 PM
03/11/11 03:00 PM
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Joined: Jan 2007
Posts: 1,668
Mi,U.S.A.
mike s
top fuel
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top fuel
Joined: Jan 2007
Posts: 1,668
Mi,U.S.A.
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At 6000 rpms the pressure would have to be less than 35 to literally starve the engine.That is it would be the minimum to overcome inertia per bearing size.However the pressure is low for 6000 rpm.10 psi per 1000 rpm is a safe minimum.Somewhere you are leaking pressure.
Leave the gun.......take the Cannoli's....Mike
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Re: Oil Pressure vs High RPM's ?
[Re: Junky]
#948533
03/11/11 04:42 PM
03/11/11 04:42 PM
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Joined: Nov 2007
Posts: 21,819
Kirkland, Washington
Pacnorthcuda
Too Many Posts
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Too Many Posts
Joined: Nov 2007
Posts: 21,819
Kirkland, Washington
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Quote:
Thanks for the assurances guys. I may get a Milodon adjustable pressure relief valve to raise it a tad.
That is likely to not raise it all. Does the pressure go over 60psi when cold (I bet it does), or does it top out in the 50's???
Your current pressure valve/spring is likely NOT operating in the 50's (and it shouldn't).
You don't have enough flow, with that weight oil, to build more psi than what you are seeing.
A HV pump, or heavier oil (20w50, because its harder to push through small spaces) will increase your hot pressure.
So will fixing the root cause--likely excessive main/rod bearing clearences.
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Re: Oil Pressure vs High RPM's ?
[Re: RapidRobert]
#948537
03/12/11 12:01 AM
03/12/11 12:01 AM
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Joined: Feb 2005
Posts: 4,311
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,311
Prospect, PA
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Quote:
Quote:
Pressures are fine.
what Stump said, You're good
But it is low and you might want to know why.
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Re: Oil Pressure vs High RPM's ?
[Re: BSB67]
#948539
03/12/11 01:03 AM
03/12/11 01:03 AM
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Joined: Jan 2003
Posts: 32,922
Grand Prairie,Texas
stumpy
I Win
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I Win
Joined: Jan 2003
Posts: 32,922
Grand Prairie,Texas
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Quote:
Quote:
Quote:
Pressures are fine.
what Stump said, You're good
But it is low and you might want to know why.
Why do you think that's low. Unless it's a brand new no mile motor those pressures are fairly normal if that is an in gear at idle 20psi. My 408 runs about 60psi at 6500 and 20psi in gear at idle(750 rpm}. After racing it for 2 years at those pressures I still show very little bearing wear.
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Re: Oil Pressure vs High RPM's ?
[Re: stumpy]
#948541
03/12/11 09:28 AM
03/12/11 09:28 AM
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Joined: Feb 2005
Posts: 4,311
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,311
Prospect, PA
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Quote:
Quote:
Quote:
Quote:
Pressures are fine.
what Stump said, You're good
But it is low and you might want to know why.
Why do you think that's low. Unless it's a brand new no mile motor those pressures are fairly normal if that is an in gear at idle 20psi. My 408 runs about 60psi at 6500 and 20psi in gear at idle(750 rpm}. After racing it for 2 years at those pressures I still show very little bearing wear.
I did not say it is a problem. I believe that it is low enough that it is worth looking into and understanding why. I know nothing about his build. If its a motor with 0.003" rod and main bearing clearances, full groove mains, designed to put a lot of oil up top, and has a std pump pressure relief spring - it makes perfect sense - would not change a thing.
But, if its a stock rebuild with stock clearances, half groove mains conventional oiling, 15/40 oil, and the pump is good (not to necessarily confuse a new Melling pump with good), then something is not right or not what it should be. Is it enough to matter, probably not.
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Re: Oil Pressure vs High RPM's ?
[Re: Junky]
#948542
03/12/11 09:30 AM
03/12/11 09:30 AM
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Joined: Feb 2005
Posts: 4,311
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,311
Prospect, PA
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Quote:
I gotta say I trust RapidRobert and stumpy's opinion.
Okay
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Re: Oil Pressure vs High RPM's ?
[Re: ahy]
#948543
03/12/11 02:25 PM
03/12/11 02:25 PM
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Joined: Nov 2007
Posts: 21,819
Kirkland, Washington
Pacnorthcuda
Too Many Posts
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Too Many Posts
Joined: Nov 2007
Posts: 21,819
Kirkland, Washington
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Quote:
If its 52 cold, it may just be a regulator spring on the low side of tolerence. The adustable spring may fix it. While I've never done it, I understand its also possible to simply shim up the existing spring with small flat washers.
Agreed.  Junky--if your cold PSI tops out at 52psi (same as your hot) then that's indicative of the pressure bypass valve in the pump opening up, and 52 is on the low side.
Simply take off the big nut at the back of the pump and find a washer or 2 that will fit inside the Nut/cap. That preloads the spring a little more and makes the valve (its a metal cylinder that uncovers a dump-port when under pressure) harder to move into the bypass position.
You will notice higher pressure.
I have done it, and in your case I think it will work.
Easy.
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Re: Oil Pressure vs High RPM's ?
[Re: Junky]
#948544
03/12/11 02:53 PM
03/12/11 02:53 PM
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Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOc !
The village idiot's idiot
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The village idiot's idiot
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
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Quote:
It's a 4 quart pan one that's on a '71 383. I run a windage tray. With new oil filter I run 5 quarts of oil.
I would be a little concerned about pumping all the oil outa'-da'-pan. If I were you ...I would look-into buying a larger capacity pan.
FOR NOW ... make sure you DO get the oil nice-and-warm before you take-it up-to 6,000 rpm.
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Re: Oil Pressure vs High RPM's ?
[Re: Pacnorthcuda]
#948545
03/12/11 04:52 PM
03/12/11 04:52 PM
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Joined: Jan 2003
Posts: 5,186
Wherever I am.
Junky
OP
master
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OP
master
Joined: Jan 2003
Posts: 5,186
Wherever I am.
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Quote:
Quote:
If its 52 cold, it may just be a regulator spring on the low side of tolerence. The adustable spring may fix it. While I've never done it, I understand its also possible to simply shim up the existing spring with small flat washers.
Agreed. Junky--if your cold PSI tops out at 52psi (same as your hot) then that's indicative of the pressure bypass valve in the pump opening up, and 52 is on the low side.
Simply take off the big nut at the back of the pump and find a washer or 2 that will fit inside the Nut/cap. That preloads the spring a little more and makes the valve (its a metal cylinder that uncovers a dump-port when under pressure) harder to move into the bypass position.
You will notice higher pressure.
I have done it, and in your case I think it will work.
Easy.
Good to know that. Thanks. I'll try the shim.
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Re: Oil Pressure vs High RPM's ?
[Re: dOc !]
#948546
03/12/11 04:56 PM
03/12/11 04:56 PM
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Joined: Jan 2003
Posts: 5,186
Wherever I am.
Junky
OP
master
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OP
master
Joined: Jan 2003
Posts: 5,186
Wherever I am.
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Quote:
Quote:
It's a 4 quart pan one that's on a '71 383. I run a windage tray. With new oil filter I run 5 quarts of oil.
I would be a little concerned about pumping all the oil outa'-da'-pan. If I were you ...I would look-into buying a larger capacity pan.
FOR NOW ... make sure you DO get the oil nice-and-warm before you take-it up-to 6,000 rpm.
I never run the engine hard until it's up to operating temp. I'm not like some of these guys that take off from a car show or cruise-in, after setting hours, doing burn outs or red lining their engines through the gears leaving. That's really hard on parts!!!
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Re: Oil Pressure vs High RPM's ?
[Re: Junky]
#948547
03/12/11 06:21 PM
03/12/11 06:21 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
master
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master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
Quote:
Quote:
If its 52 cold, it may just be a regulator spring on the low side of tolerence. The adustable spring may fix it. While I've never done it, I understand its also possible to simply shim up the existing spring with small flat washers.
Agreed. Junky--if your cold PSI tops out at 52psi (same as your hot) then that's indicative of the pressure bypass valve in the pump opening up, and 52 is on the low side.
Simply take off the big nut at the back of the pump and find a washer or 2 that will fit inside the Nut/cap. That preloads the spring a little more and makes the valve (its a metal cylinder that uncovers a dump-port when under pressure) harder to move into the bypass position.
You will notice higher pressure.
I have done it, and in your case I think it will work.
Easy.
Good to know that. Thanks. I'll try the shim.
My 383 was exactly the same psi as yours a bit higher at idle (900 rpm) i installed the hi psi spring now it stays at 72psi anything over 1500 rpm, but obviously the idle psi is the same. you should be fine just the way yours is now but add the spring if your worried
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