OIL PUMP PSI
 

I have a 1967 GTO with the engine out of it.

Back many moons ago when I started this project, the advice I got at that time was that for my stock 400, an 80psi oil pump would be a smart upgrade. So, many years ago, I purchased a Melling 10541:

https://butlerperformance.com/i-3164...h.html?q=10541

Now I'm not entirely convinced that the 80psi is the best choice.

I've read a lot of forums and it seems that the general consensus is that 80psi is unnecessary, and can even be harmful to a degree. Some people are of the opinion that it can put unneeded stress on the gaskets, can wear the cam/distributor gear prematurely as well as other parts, and will rob horsepower.

Just as I was coming to the point of considering buying a 60psi pump, I spoke to Dale from Melling tech who disagreed with all of this and said that the 80psi "shouldn't" cause any problems and the upgrade would be fine.

What do you guys think?

While I'm at it, let me ask a couple of other questions.

What is the best way to tack the pickup tube so it doesn't fall out or shift out of place? There seems to be a WIDE range of opinions on this.

Should I buy a hardened oil pump drive shaft? I think it could be cheap insurance. I'm looking at this one:

https://butlerperformance.com/i-2445...-opds-std.html

Any other advice?

Thanks for your help everyone!

SusieQ

OIL PUMP PSI
 

Oil pump choice depends on a lot of factors, bearing clearances,rod side clearance, crank end play and intended max rpm. If this is a stock build with close to factory clearances the 60 psi pump should be fine. Also the hardened drive is good insurance for either pump.

I'd agree with Bill that 60psi should be more than adequate.
 

If your engine is fairly stock, with 'normal' bearing clearances, 60PSI is plenty.

But you don't need to purchase a different pump to get to 60psi. Just change out the relief spring assembly to a 60psi setup.

And, YES, get the hardened driveshaft. One less thing to have an issue with.

Few things. You must use a hardened shaft with a 80lb pump. But, do not use that shaft in the link. I do not see the little 'dimples" or a clip to prevent the shaft from being pulled up too far when your distributor is removed. Its made by AP. And their shortened shaft that comes with the IA2 block does not have those either so I will not use their shaft.
That shaft gets pulled up and falls off the pump it will more than ruin your day. Nightmare makes the proper shaft for IA2 blocks so I am sure they make the correct one for stock blocks too.
And there is no reason to run a 80lb pump in any Pontiac that is not some loose big power beast. And even then most do not use them.
Your pump, I have a Dyna Gear 80lb pump and it comes with a kit to turn it into a 60lb pump. Also came with the right hardened shaft with C clip. I bet Melling has the parts needed to turn it into a 60lb pump. Might want to ask. Folks did use to cut either .75 turn or 1.5 turns out of the spring to drop the pressure. But I would not do that, hit or miss.
BTW, I have a 455 with 60lb pump forever. Crosses the line at 60lbs, no need for a 80lb pump.

keep in mind the unofficial rule is 10psi per 1000 rpm. unless you plan on running 8000rpm, or over 6000 rpm frequently, the 80lb pump is overkill & not needed. especially if you live in colder climates &/or run thicker oil.

1) You can take a spring and cap from any normal Pontiac Oil Pump and swap the parts with the 80 psi spring cup and spring. I used to buy the 80 psi spring cup and spring from Melling for about $4.00 and convert the stock 60 psi pumps to 80 psi pumps.
So going the other way, if you have your old pump laying around should work unless the pump had 150,000 miles on it.

2) Pure street vehicle I would run the 60 psi pump parts too.

3) The hardened Driveshaft is a good idea if you run the 80 psi pump but I have never seen a stock 60 psi driveshaft fail in normal usage. Not Racing stuff with thick oil.
Maybe if you got a chunk of material inside the gears of the pump from a crappy oil pick-up design.

4) I would run the later oil pan with the baffle welded in the pan. Helps on right hand turns off freeway ramps.

Tom V.

Concerning the parasitic loss from a 80 lb pump. This from Jim Butler on the subject....

"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."

Curious, anyone have testing data with the difference in power/torque loss on a engine between the two pumps ?

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


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60 psi

Every so often, someone comes along and proposes reducing oil pressure to free up horsepower..............


https://www.eng-tips.com/viewthread.cfm?qid=350063

Interesting read, not for any endorsement but offered for general interest.


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Built a 73 block to SD specifications Nunzi did all the machine work. He asked me what rpm the max was for the engine. I said max 6K to 6.2 K. He asked about the oil pump, since it was a block I got from the junk yard I told him it was new. I gave him a NOS SD pump, he switched the spring to 60 psi and did work to the pump gears. He said no reason to run a 80 psi pump.

So for a 6000-6200 rpm street engine... who is correct Butler or Nunzi. NOT to insinuate either is 'wrong'.



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Good stuff guys.

I like the idea of switching the spring to convert it to a 60psi. That's a big help if I decide to go the 60psi route. I was thinking I had to buy an entire new pump.

I'll look into the cost of the spring and then make a decision on what I'm going to do.

The collective wisdom is that the 80psi isn't necessary, and would "probably" be fine, or "shouldn't" cause any problems. I'm not a big fan of doing things that have disclaimers such as "probably and "shouldn't," especially when there's no clear advantage, so I'm leaning towards changing that spring.

An added advantage going with the 60psi is I don't really need to spend money on a hardened driveshaft.

Thanks again guys!

The first time I ever tried an 80 psi pump the new engine started and ran then quit. Pulled the distributer cap off and the rotor wasn’t turning. Pulled it out found nothing wrong. Pulled a valve cover off and the valves were not moving. Found that the key on the cam sheared. Replaced the key and it start up an ran, when we rev’d it up the cam key sheared again. Grrrrr...20 some years later I can smile about it. We weren’t back then. We pulled the engine and put in a 60 psi spring and never had any trouble after that. Not saying it will happen to you. But Pontiac didn’t exactly overbuild the cam gear or the cam drive.

The hardened shaft is needed for a 60lb pump. Thats what Dan Whittmore sent me with my pump. I asked him about it and was told you can still twist a shaft with a 60lb pump on a cold morning. Just do it, peace of mind is worth the 30 or so bucks.

Not saying that Dan Whitmore was not telling the truth on that cold morning deal but honestly, my car/engine for example has not been started on a cold morning in almost 20 years and I live in Michigan. I have a Truck or an Escape for those cold mornings. Not my 1964 GTO convertible.

SusieQ, your info does not say what part of the USA, I assume, you live it.

Tom V.

One of the main problems with the 80psi SD pump was that in the north when it middle of winter a few SD cars blew the oil filter on cold morning starts.
If your car is outside and has an engine block heater pugged in keeping the oil warm in the winter no problem. Yes I also had the hardened shaft for
extra insurance.

Ask yourselves this in regards to the need for oil pressure that being
On the 60s 421 SD motors ( same diameter mains as a 455 ) that ran the banked ovals at 6200 rpm near constantly how much oil pressure did they run?

"What is the best way to tack the pickup tube so it doesn't fall out or shift out of place?"

I would NOT weld the pick-up to the pump for any reason. I see this recommended a lot, but I've had enough engines come in here where the weld broke off a piece of the pump and the pick-up ended up in the pan to avoid that deal altogether. While on the subject NEVER weld the retaining ring on a TH400 drum for the intermediate sprag either, get the 4L80E spiral lock. Seen WAY too many of those have the sprag knock the welds off the ring and the trans looses second gear and has to come out for repairs.

Several much better methods to accomplish that task. For deep sump pans with the taller aftermarket pick-ups I weld a strap to the pick-up then put the other end under one of the pump cover bolts.

For stock pick-ups they are driven in place, then I drill a small hole thru the pump and pick-up about 1/4" from the edge and tap it for a hardened allen drive machine screw, usually 8-32. This is done in the shop vise, then the cover removed to blow out any chips that may have fallen inside.

With either method the pick-up can't fall out or turn and you aren't putting any heat on the pump from any type of welding operation........Cliff

Attaching the pick-up didn't happen from the factory, but the material those OEM pick-ups were made from was better. Aftermarket pick-ups are "soft" metal and don't have any "memory" to keep them in place, so it is imperative that you take the extra time to make sure is doesn't fall off and end up in the assembly.......Cliff

As far as oil pressure goes with correct bearing clearances and proper crankshaft main bearing alignment, correctly sized rod big ends, and correctly assembled the stock pump with the 60psi spring is more than adequate for what you are doing.

Even on the higher HP builds we've done, several over 700hp the stock Melling pump was used and we've never had a single issue anyplace related to bearings or engine failure due to a pressure lubricated parts. Matter of fact the only engine I've ever lost was a "high-end" build before the aftermarket blocks were available and it broke a piece of lifter bore off the block even with a brace in it. The problem with that engine, IMHO was that the camshaft was just too big and aggressive and side loading things beyond the capabilities of the lifter bore design. It had previously led a good life for over 10 years at a lower power level with a pretty hefty flat solid camshaft in it pushing the car to low 10's. The solid roller upgrade with a butt-ton more spring pressure and super aggressive lobes was good for 17 drag strip runs before it gave up, and the aftermath wasn't pretty!........Cliff

Here's the take from Greg at Butler Performance tech:

It should be OK to use as the stock ram air 4 and super duty cars came stock with the 80psi pump

I don’t have a different spring all I can offer is a complete 60psi pump

ugh lol