[68 Firebird]

been following this thread and a lot of good info in here. All engines were built by different mechanics and too different specs. Too many variables at play. Everyone has there own real world experience and preference. Thicker oil means higher pressure and thinner means less pressure at hot idle in my car. Swapped to Crower CamSaver Lifters a few years ago. Spoke to Crower tech to get oil recommendations. Tech was nice and said they go for lightest oil after break-in and recommend 5W30or10W30. Said they want oil to lifters as fast as possible and the thinner oil would FLOW better at startup thru flats on lifters directly to cam surface. Well broke her it with SAE30 and then dumped oil and filter. Running VR1 10W30 and man those lifters are quiet even after sitting in garage for months. Startup is 65 and 50 when she comes off idle. Once fully up to temp 20 PSI in gear and jumps with any throttle movement. Will see 15 coming off longer highway run, but will come back up to 20 after a few miles. Crower tech did advise slightly lower idle psi due to extra oil flow due to leakage path. Also pressure reading is from dizzy location using mechanical gauge with copper line. At breakin I had a spare gauge hooked up to oil filter adapter and for reference that one showed 4-6 PSI higher at idle then dizzy gauge. Just my experience. Gerry

[HWYSTR455]

Originally Posted by 69 Limelight

Google "Amsoil Viscosity Tech Article", click on "Motor Oil Viscosity Grades Explained in Layman's Terms". Good read. Found paragraphs 11, 12, & 13 especially interesting and explains why Valvoline tech engineers recommend changing VR1 20W-50 at 3,000 mile intervals, or less, but this reason would also apply to all 20W-50's or 10@-40's.

My understanding was that the Valvoline VR-1 recommended change intervals are due to the additive package used in 'racing' oils, which don't last as long as 'street' oil additive packages. Has nothing to do with the viscosity. (though I did not read the article)

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[#1965GTO]

Well if you find the answer I'd like to know. Your expectation of oil pressure that high is unfounded. More than one very qualified machinist and mechanic have told me anything above 40 PSI oil pressure is a pure waste of horse power. They also state that pressures in the range you mention will cause bearings to wash. In other words remove the bearing face material even with the hardest bear faces they make.
My concern as well as yours is the low pressure at idle. Mine is a 400 with King bearings at .002 to .003. and Melling standard pump, Voodoo hydraulic flat tappet cam and lifters. Pressure with VR-1 straight 30 weight conventional is 65 cold and 20-25 warmed up, 200 water temp. I had VDO quality gauge set originally and questioned each. So I replaced them with a good set of SW. There was some difference, both sets being mechanical. The temp went down 20 degrees and the oil pressure was up about 5 lbs. on both ends.
I never stab the gas not in gear. Revving that high with no load will cause all kinds of problems. From an idle a modest increase to 1500 RPM and the pressure is back to the 40 LBS. range.
The last time I had the motor out I even detailed a new oil pump. I reduced the gear to plate clearance by sanding the base of the new pump body on a flat surface with some 600 grit. It's been awhile so I have forgot the clearance I was going for. I think that may have made a slight difference.
Pontiac had a recall in about 68 or 69 because they were literally blowing filters apart due to the wrong spring in the bypass. An old friend of mine had one of those cars when he lived in Salt Lake City. He had to be towed in twice before the dealership got the recall to change the oil filter adapter. He said the bearings failed a couple of months later. After he got the new warranty replacement motor installed he traded the car for a 69 Charger with a Hemi.

[gtofreek]

Originally Posted by #1965GTO

Well if you find the answer I'd like to know. Your expectation of oil pressure that high is unfounded. More than one very qualified machinist and mechanic have told me anything above 40 PSI oil pressure is a pure waste of horse power. They also state that pressures in the range you mention will cause bearings to wash. In other words remove the bearing face material even with the hardest bear faces they make.
My concern as well as yours is the low pressure at idle. Mine is a 400 with King bearings at .002 to .003. and Melling standard pump, Voodoo hydraulic flat tappet cam and lifters. Pressure with VR-1 straight 30 weight conventional is 65 cold and 20-25 warmed up, 200 water temp. I had VDO quality gauge set originally and questioned each. So I replaced them with a good set of SW. There was some difference, both sets being mechanical. The temp went down 20 degrees and the oil pressure was up about 5 lbs. on both ends.
I never stab the gas not in gear. Revving that high with no load will cause all kinds of problems. From an idle a modest increase to 1500 RPM and the pressure is back to the 40 LBS. range.
The last time I had the motor out I even detailed a new oil pump. I reduced the gear to plate clearance by sanding the base of the new pump body on a flat surface with some 600 grit. It's been awhile so I have forgot the clearance I was going for. I think that may have made a slight difference.
Pontiac had a recall in about 68 or 69 because they were literally blowing filters apart due to the wrong spring in the bypass. An old friend of mine had one of those cars when he lived in Salt Lake City. He had to be towed in twice before the dealership got the recall to change the oil filter adapter. He said the bearings failed a couple of months later. After he got the new warranty replacement motor installed he traded the car for a 69 Charger with a Hemi.

Sorry but that statement from machinist is total hog wash. Blown drag race engine frequently run over 200 PSI without "bearing Wash". In my 40 years of building engines[25 years professionally] I have never seen bearing wash happen in anything. Even with stock replacement bearings. That's just an old wives tale that people keep passing down. I think it may have started way back when they babbit filled bearings. Like back in the 30's. Totally not true in todays world.

[JSPONT]

Originally Posted by HWYSTR455

My understanding was that the Valvoline VR-1 recommended change intervals are due to the additive package used in 'racing' oils, which don't last as long as 'street' oil additive packages. Has nothing to do with the viscosity. (though I did not read the article)

.

Racing oil has no detergent in it like regular conventional oil I was told.

[Formulas]

Whatever API rating a oil has should tell you about detergents

[Steve C.]

Repeat information and to reinforce gtofreek's statement.....

“We’ve run as much as 100-psi on some engines and have never experienced any bearing wash issues. Excessive distributor or cam gear wear can result, particularly with a bronze gear, but we consider positive cam-gear oiling a must when running a roller camshaft, and we found that it significantly improves distributor gear life.”
Jim Butler

A repeated link, but more here on Pontiac oil pumps and the source of that comment :

https://www.hotrod.com/articles/hppp...-observations/


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["QUICK-SILVER"]

With standard volume oil pumps, HP requirements and gear wear doesn't go up untill pressure exceeds 60 psi. In the case of the OP's car...That would be at higher RPMs when the engine needs the extra protection.

It's high volume pumps that create more load under normal driving conditions.

Clay

[gtofreek]

But in Pontiac's case, there are no high volume pumps from Melling, just high pressure pumps. Both have the same gears, so same volume. They just have different bypass springs.

[grivera]

In my case with pressure not matching the pump psi is it safe to assume additional wear isn’t an issue (outside of cold high idle)?

["QUICK-SILVER"]

Originally Posted by grivera

In my case with pressure not matching the pump psi is it safe to assume additional wear isn’t an issue (outside of cold high idle)?

I think it's good to go. The oil is just getting skinnyer when hot. Didn't what you post show the 10 psi min. per 1,000 RPMs.

In this thread I missed what the build even is. If it's a stroker project, I'd want a little more hot psi if it's gonna get thrashed on.

Clay

[grivera]

Originally Posted by "QUICK-SILVER"

I think it's good to go. The oil is just getting skinnyer when hot. Didn't what you post show the 10 psi min. per 1,000 RPMs.

In this thread I missed what the build even is. If it's a stroker project, I'd want a little more hot psi if it's gonna get thrashed on.

Clay

It’s the build in my signature 400/461 stroker, .0025 mains/rods. 80 psi pump, 19/32” check ball instead of 5/8

[Bruce Meyer]

After reading through these posts I decided to try 20-50 VR1. In the past I always used 10-30 VR1. Never had any oil related problems but I always had noisy Comp Cams Magnum rockers. Hot oil pressure at idle in gear was 20 lbs. With the 20-50 I now have 30 lbs at hot idle and no rocker noise. Im sold.

[JSPONT]

Originally Posted by Bruce Meyer

After reading through these posts I decided to try 20-50 VR1. In the past I always used 10-30 VR1. Never had any oil related problems but I always had noisy Comp Cams Magnum rockers. Hot oil pressure at idle in gear was 20 lbs. With the 20-50 I now have 30 lbs at hot idle and no rocker noise. Im sold.

Are you trying to start trouble here? LMAO

[grivera]

Originally Posted by Bruce Meyer

After reading through these posts I decided to try 20-50 VR1. In the past I always used 10-30 VR1. Never had any oil related problems but I always had noisy Comp Cams Magnum rockers. Hot oil pressure at idle in gear was 20 lbs. With the 20-50 I now have 30 lbs at hot idle and no rocker noise. Im sold.

What is your idle rpm ?

[Bruce Meyer]

Originally Posted by grivera

What is your idle rpm ?

around 700 in drive

[phil400]

Originally Posted by gtofreek

But in Pontiac's case, there are no high volume pumps from Melling, just high pressure pumps. Both have the same gears, so same volume. They just have different bypass springs.

I always thought the good'ole go to M54DS pump was a high volume pump.

[Kenth]

There are no higher volume pump from Melling than what the currently carrying for Pontiac V8. They are all "high volume" using the 3/4" pickup tube.

In "the day" Pontiac used a 40 lbs pump with 5/8" pickup tube for the lower perf engines.

[phil400]

Originally Posted by Kenth

There are no higher volume pump from Melling than what the currently carrying for Pontiac V8. They are all "high volume" using the 3/4" pickup tube.

In "the day" Pontiac used a 40 lbs pump with 5/8" pickup tube for the lower perf engines.

Oh ok thanks.

[steve25]

A motors rotating Assy's need for oil volume levels off by 4500 rpm and at that point all that is needed is enough pressure to keep the centerfugal forces from within the Crank from stopping the oil from entering into the Crank and getting into the rod Bearings.

If your oil is up to temp and the filter is not a restriction and your Bearing clearances are not excessive then a motor with 3 inch mains will live just fine when blasted to 7000 rpm with a 60 psi pump.

If I am going to take a 3.250" main motor to over 6000 rpm , but not more then 7000 rpm then I would shim the pump to 70 psi .