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Old 12-03-2005, 04:26 PM
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oil pressure question

i have a 69 chevelle with a 350 sbc i have done some work too the car it has a 670 holley ,holley street dominator intake,blackjackheaders,mild comp cam.still in process of building.but my question is about my oil pressure when i start it from a cold start its sits at 55-60psi and when it warms up it drops to 25-30 and it will stay there at idle.while running at say 2500-3000rpms it is at 45-55 is it normal for it too be that low at idle or should i get ready too replace the pump soon? this engine is not fresh it has some miles on it but does not smoke or have any power loss.thanks

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Old 12-03-2005, 04:32 PM
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Suprised it doesn't drop lower than that at idle warmed up. I've seen plenty drop down to 15-20psi and run fine.

If ain't broke don't fix it!
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Old 12-03-2005, 04:34 PM
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Quote:
Originally Posted by jody chevelle
i have a 69 chevelle with a 350 sbc i have done some work too the car it has a 670 holley ,holley street dominator intake,blackjackheaders,mild comp cam.still in process of building.but my question is about my oil pressure when i start it from a cold start its sits at 55-60psi and when it warms up it drops to 25-30 and it will stay there at idle.while running at say 2500-3000rpms it is at 45-55 is it normal for it too be that low at idle or should i get ready too replace the pump soon? this engine is not fresh it has some miles on it but does not smoke or have any power loss.thanks
Most of the Chevy experts on this forum will tell you that 10 idling hot and 10 psi per 1000 rpm is OK...... (yikes)

so they will insist that 10 and 30 is great.... They will consider your 25 and 45 plenty high.
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Old 12-03-2005, 04:36 PM
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Quote:
Originally Posted by xntrik
Most of the Chevy experts on this forum will tell you that 10 idling hot and 10 psi per 1000 rpm is OK...... (yikes)

so they will insist that 10 and 30 is great.... They will consider your 25 and 45 plenty high.

Ok , I should add then IMO! and this is just from the engines/vehicles I've ran.
Correct me if this is way off!
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Old 12-03-2005, 04:42 PM
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your oil psi is fine, a chevy guy
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Old 12-03-2005, 04:49 PM
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reply to oil pressure question

Quote:
Originally Posted by TwistedTrbl
Suprised it doesn't drop lower than that at idle warmed up. I've seen plenty drop down to 15-20psi and run fine.

If ain't broke don't fix it!
cool i thought so i guess i should trust my instincts more .i like your quote man,mines if it ain't broke dont buy it .
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Old 12-03-2005, 08:45 PM
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If the engine is out of the car, why not change the pump now? Its cheap insurance if it has a lot of miles on it. BTW...the pressures sound good to me too.
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Old 12-03-2005, 09:04 PM
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oil pressure is good, notice the next oil change it will be higher for a 100 miles or so and then come back down some ................ the viscosity changes
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Old 12-04-2005, 07:16 AM
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I had the same concern with a fresh chevy 350. Cold it has 50 PSI on the gauge, all warmed up at idle it has @15 PSi, get above 1000 RPM and it gets to 40 PSI and stays there. I am using a relocated oil filter kit and oil cooler which I thought might be the cause. I use Mobil 1 5-30 oil which concerned me as I noticed these issues after engine break in and the switch to synthetic oil. There are no lifter ticks and the engine runs strong. I'd say from personal experience that you will be OK.
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Old 12-04-2005, 11:31 AM
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Quote:
Originally Posted by gazrnr
I had the same concern with a fresh chevy 350. Cold it has 50 PSI on the gauge, all warmed up at idle it has @15 PSi, get above 1000 RPM and it gets to 40 PSI and stays there. I am using a relocated oil filter kit and oil cooler which I thought might be the cause. I use Mobil 1 5-30 oil which concerned me as I noticed these issues after engine break in and the switch to synthetic oil. There are no lifter ticks and the engine runs strong. I'd say from personal experience that you will be OK.
Chevys are notorious for very poor oil pressure but that seems like quite a discrepancy. It does not seem logical that you would have 15 @ 750 and then 40 @ 1200 rpm.

I would be running 15w50 Mobil 1 if I were you. I have been using M1 exclusively for 20 years.
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Old 12-04-2005, 11:34 AM
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If I run anything but 5-30 oil it voids the warranty on the crate motor from GM.
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Old 12-04-2005, 11:58 AM
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Speaking of oil pressure answer me this... New engine, gobs of oil pressure, engine temp reaches 190 and continues to run 5 min, no change in water temp, but the oil pressure drops to 20 psi @ 2000 and 0 at idle.. using a mech guage that was checked.. Cam bearing?

2wld4u
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Old 12-04-2005, 12:02 PM
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Your oil pressure is just fine.
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Old 12-04-2005, 12:40 PM
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Quote:
Originally Posted by 2wld4u
Speaking of oil pressure answer me this... New engine, gobs of oil pressure, engine temp reaches 190 and continues to run 5 min, no change in water temp, but the oil pressure drops to 20 psi @ 2000 and 0 at idle.. using a mech guage that was checked.. Cam bearing?

2wld4u
Oil pressue is a measure of the resistence to flow.

I have had a theory that high valve spring pressure pushes the cam down to the bottom so much that the bearing clearance blows the oil out. I also believe that the cam shifts longitudinally (loose button) that the shift in bearing alignment loses oil too. I also believe that many hydraulic flat tappet lifters dump excessive oil around the pushrods and the lifter bore. Experience has shown that tighter main and rod bearing clearances does not help SBC oil pressure very much.

gazrnr (Apparently Chebby crate engines have low oil pressure too.)

2wld4u Your oil pressure is not fine in my opinion. Under 10 at idle and you have a serious serious problem. True ZERO is .... YIKES.

I think that each of you might have an oil pump-gear side-clearance problem that manifests itself as the oil temp goes up. I bet it would be sucky on a 95* day on an interstate trip when the oil gets to 230*!!!!!

There was a thread about this not long ago and pictures of his pump. I will try to find it and post it here.

Obviously you have internal clearances that are excessive.

Each of you, If it were me, I would change to 20w50 cheapo oil and see what pressures you get. You can change it back in 50 miles. $ 10

If that helps the pressure, I would consider a HV pump with a 60 psi spring.

Always remember, bad oil is better than NO oil.

x
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Old 12-05-2005, 11:10 AM
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Quote:
Originally Posted by xntrik
Oil pressue is a measure of the resistence to flow.

I have had a theory that high valve spring pressure pushes the cam down to the bottom so much that the bearing clearance blows the oil out. I also believe that the cam shifts longitudinally (loose button) that the shift in bearing alignment loses oil too. I also believe that many hydraulic flat tappet lifters dump excessive oil around the pushrods and the lifter bore. Experience has shown that tighter main and rod bearing clearances does not help SBC oil pressure very much.

gazrnr (Apparently Chebby crate engines have low oil pressure too.)

2wld4u Your oil pressure is not fine in my opinion. Under 10 at idle and you have a serious serious problem. True ZERO is .... YIKES.

I think that each of you might have an oil pump-gear side-clearance problem that manifests itself as the oil temp goes up. I bet it would be sucky on a 95* day on an interstate trip when the oil gets to 230*!!!!!

There was a thread about this not long ago and pictures of his pump. I will try to find it and post it here.

Obviously you have internal clearances that are excessive.

Each of you, If it were me, I would change to 20w50 cheapo oil and see what pressures you get. You can change it back in 50 miles. $ 10

If that helps the pressure, I would consider a HV pump with a 60 psi spring.

Always remember, bad oil is better than NO oil.

x

I was using 20/50W casterol GTX and a solid lifter cam... I found the problem, it was a plug above the rear main cap...

2wld4u
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