[dpoltzer]

My stock 400 puts out 80 PSI when cold (20-50 oil) and around 60 psi when hot at idle. Gauge is pegged when WOT. I am guessing that the builder put a high pressure 80 psi oil pump in some years ago. Engine also leaks oil so I was planning on changing the pump to a 60 psi mellings unit. Anything else I can try besides maybe 10-30 oil. Is Mellings a good brand to go with?

[Formulajones]

My RAIII 400 does the same and has been that way for 30 years.

I ve got 80 on a cold start, 60 at idle in gear once it gets some heat in it, and if I cruise the highway for 20-30 minutes I'll get 40 hot idle, however oil pressure still climbs nicely with rpm and yes it's at or very near the top of the gauge (80) at wot throttle.

I daily drive it this way and competed in numerous drag race events over the last 30 years, it's fine, no oil leaks, I don't even concern myself with it.

If ya want you could try thinner oil see if that makes you feel better otherwise I honestly wouldn't worry about it.

[HWYSTR455]

If you're concerned about the oil psi, use 10-30 instead of 20-50.



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[steve25]

If you have to pull the motor to fix the oil leak then get a 60 psi pump and instead of going through the project of installing the pick up tube in that pump just swap the 60 psi spring into the pump on the motor now.

Having near 60 psi constantly is putting way more of a load on the Distributor gear then the standard one was made to put up with, and especially if the oil galley plug that’s in front of the gear was not mod’ed with a small hole to hit the gear with oil.

Another concern about running the 80 psi pump is if the builder used a HD pump driveshaft, or just the stock one.

If I where you in the least I would run a 10W30 oil.

[Formulajones]

Yeah I've heard those stories before. So far after 30 years, ya know how many distributor gears I've been through? Zero, zilch, nada. Don't have the oil galley plug mod either. Stock pump drive shaft too.

This isn't the only engine that I've had like this either.

[steve25]

Just because you have not had your back side bitten does not mean it doesn’t happen.

Do you not have life insurance for you and your family?

Is not drilling a hole in a brass pipe plug and buying a HD driveshaft cheap insurance ?

I once took a part a factory built 50K mile street motor with a 60 psi pump to find the factory oil pump drive twisted near 75 degrees, can you predict for me how much longer it would have gone?

[Dragncar]

I drilled .030 hole in the factory steel 3/8" plug. No need for brass.
Ran a roller cam for a decade and the gear looks new. So I ran it as is in the new engine.

[mgarblik]

I run an 80 LB. pump in all my HP builds. Run clearances a little on the loose side. Used a lube hole for the brass dist. gear. 10W-30 oil. Cold start may see 100 PSI for 2-3 minutes, then settles in nicely around 30-60 PSI in regular street driving, depending on RPM of course. Fully warmed-up idle pressure, 25-30 PSI. Full throttle, high RPM just under 80 PSI. I do use a hardened pump shaft. Kinda feel like a dist. gear every 10 years is way less hassle than main and rod bearings or a hole in the block if I just can't resist a few 6200 RPM gear changes. Everyone has pretty passionate feelings about oil pressure. I can honestly say I have never in my life witnessed engine damage from too much oil pressure. Can't say the same for too low. While your engine is apart, as mentioned, you can just change the spring and cup to 60 PSI if you prefer.

[Goatracer1]

I'm with Fomularjones. My car has run those pressures since 1998.

[Formulajones]

Originally Posted by steve25

Just because you have not had your back side bitten does not mean it doesn’t happen.

Do you not have life insurance for you and your family?

Is not drilling a hole in a brass pipe plug and buying a HD driveshaft cheap insurance ?

I once took a part a factory built 50K mile street motor with a 60 psi pump to find the factory oil pump drive twisted near 75 degrees, can you predict for me how much longer it would have gone?

Someone tells you to jump off a bridge are you going to do it?

Point being is I think you guys worry too much. I've never seen a bunch so worried about so many things on their engine. Makes the Pontiac brand look questionable.

I think this garbage comes down to defective parts more so than what you guys did or didn't to to try and prevent something. But hey go right ahead and worry and modify things till your hearts content.

[Formulajones]

Originally Posted by mgarblik

I can honestly say I have never in my life witnessed engine damage from too much oil pressure. Can't say the same for too low. While your engine is apart, as mentioned, you can just change the spring and cup to 60 PSI if you prefer.

Exactly

[J.C.you]

I had a drive rod snap off at the ear and a filter oring blow out in years past. I err on moderate oil pressure, set up for the rpm limit and application of the motor. There’s hp in thinner oil too.

[steve25]

When John Delorian charged head engineer MacKeller to produce a 400 ( RA IV) that was safe to buzz to 6400 rpm the engineering team continued to use the 60 psi oil pump.
That should tell you something about the 3” main motors seeing as the factory had to warranty these motors.

[HWYSTR455]

I bought like 10 driveshafts from H-O back in the day, and a few other hardened ones along the way. All the builds I haven't done myself got hardened ones from the builder. And that's regardless of what pump they got.

I prefer the ones with the ears, but it's personal preference.

Standard dizzy gears are pretty hard, and generally last a long time, regardless of which pump you use.

Let me remind people:

https://www.pontiacv8.com/articles/2018/3/26/oilpump

"Osterhaus is quick to point out that even though the pressure bypass valves actuate at 50 and 70 psi, respectively, it doesn’t necessarily mean that oil pressure within the engine will be exactly 50 or 70 psi."

“It’s dependent upon such variables as engine speed, bearing clearances, and oil temperature and viscosity. Actual pressure could be higher or lower depending upon the particular engine and where the oil pressure reading is taken.” When dealing with a typical Pontiac V-8 and production-bearing clearances, pressure at the gauge is usually 60 and 80 psi, respectively."

Raise of hands: Who shims their' 60 psi pumps?

Just run the 80 pump and be done with it.



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[track73]

My 455 rarely sees 4800 rpm so I can't see the need for 80 psi pumps. They not only crete more wear on the distributor gear but take away some horse power.

[grivera]

Butler Performance's take on high oil pressure pumps, distributor wear, and power loss: https://www.motortrend.com/how-to/hp...-observations/

Oil Pressure Requirements

A common question from many Pontiac hobbyists is about oil pressure and just how much is required. "We generally feel at least 10 psi of oil pressure for every 1,000 rpm is the minimum requirement for reliable operation," says Butler. "We recommend 20W-50 oil for our high-performance engines, and like to see hot-idle oil pressure between 30 and 40 psi. Pressure as low as 15-20 psi doesn't necessarily present a risk as long as it isn't a sign of other problems, but the amount of time it takes pressure to climb to 60 psi or more can put the bearings at risk on a quick-revving, high-performance engine."

Butler says that since an engine with smaller-diameter main journals (3-inch) and shorter-stroke crankshafts (4.21-inch or less) is generally less stressful on the bearings, a 60-psi pump may provide adequate lubrication in a modified engine, but an 80-psi pump is a better choice. He says any performance engine with 3.25-inch-diameter main journals and/or a stroker length greater than 4.21 inches should use an 80-psi pump. "The greater oil pressure associated with the 80-psi pump improves the strength of the oil film, and better protects the bearings in large journal and/or long-stroke applications," he adds.

Common hobbyist concerns when using an 80-psi oil pump in a street engine include excessive parasitic loss, bearing wash, and premature distributor and/or cam gear wear.

"We've never seen a noticeable performance loss from the added load," says Butler. "Racers will sometimes run a 60-psi pump to reduce parasitic drag and free up a few horsepower. While that's acceptable in a dedicated race engine that's frequently torn down, it's certainly not something we recommend for all engines."

He continues: "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."

One area that many hobbyists overlook when selecting an oil pump for a particular engine is camshaft type. "Some of the aggressive hydraulic- roller-lobe profiles available today and the high-pressure valve-springs required to effectively maintain valvetrain stability can cause the roller lifter's hydraulic internals to bleed down too quickly, and that can create a performance loss. In these instances, additional pressure (75 psi or more) is required to keep the hydraulic lifters working properly," states Butler.

[Goatracer1]

My car was not babied by any means. For over 10 years it was raced running high 10's @ over 125 and is now street driven. The pressure does not stay at 80 - 100 psig all the time. Only when warming up. When it's cold it is not going to see high RPM. I don't see how that is going to damage my engine. And, it hasn't in many years of use.

[HWYSTR455]

Yeah, Will, that's the same article I posted, just a diff source.

I like the excerpts you pulled tho.

Like I've mentioned in other posts, you couple the 50psi "60 pump" with wider clearances (which many shops use) and low idle RPM, you hear people complain about 'noise' when HYD rollers are used. Or just low psi at idle.

Go figure.

Then there's the folks that shim the "60 pump" to get 70psi, which is what the "80 pump" puts out. And a lot of those people swear by the "60 pump".

If you rebuild it, just use the "80 pump". It doesn't matter if you don't 'race', or going to keep it under X RPM, it's a safety margin.


.

[Formulajones]

Ive said the same thing in the past with hydraulic rollers. Pontiacs take more spring pressure to start with compared to a typical SBC just because valve train is heavier, couple that with oil pressure too low at idle eludes to exactly what butler is saying in Will's post.

Those worried about 3 HP on a street build.........meh. you'll never feel it. I'd rather have the pressure. I can easily find more power than that else where.

Besides that it's not like it sees 80 psi and never comes down. Like I said, and the op sounded similar in his post. It mainly 80 psi on cold starts, when you shouldn't be racing the engine anyway. As it gets some heat in it, it'll come down some. Hot idle after just a few minutes is around 60 and if I get the oil hot from extended highway rpm hot idle will be around 40 which I consider a normal idle pressure for any engine. Now at that point if I run the engine wot then sure it'll get up to 80 psi but it's not like you're doing that at every stop sign and red light. The pressure basically moves like a tachometer as rpm goes up and down with a 30-40 psi swing. Perfectly fine.

[Formulajones]

To goatracers point, Ive raced mine since the mid 90's, and still race it today. During all the time Ive put well over 100k miles on it in-between the racing, and continue to use it to this day as one of our main cars for transportation.

Hell I was even doing drag and drive events with it before drag and drive events even became a thing. It's nothing for that car to see a 5-6 hour drive to an event, then proceed to race the car all weekend. Friday, Saturday, and even Sunday if I'm still in eliminations, then drive it back home 6 hours. These days everyone is afraid to go more than 30 miles from home otherwise the car is on a trailer.

Get out and drive the darn things, quit worrying about things you can't control.