[tooski]

I did a search, read a lot, but no info for what I was looking for.
Which is: What makes a 60 psi pump different from an 80 psi pump?
I would surmise that the pump build specs would be different to produce different pressure specs. That would mean that the 60 psi pump should be unable to produce 80 psi. Otherwise why would there be 2 different pumps.
I have read that a washer can be placed in the spring housing to raise the pump pressure. I believe that only raises the point at which the relief operates. Why shim the spring to relieve at 70 psi, when the pump can only produce 60 psi?
Why does the 80 psi pump require a longer spring cup? Why not just use a stronger spring?

[johnta1]

Basically just the spring pressure.
(stock type units)

The 80 lb spring housing is usually longer compared to the 60 lb one.

The pressure is variable, but the volume per 1 rpm is the same.

[Tom Vaught]

To make the 80 psi pump from the 60 psi pump, Melling (I spoke to the Engineers several times over the years) just designed a different spring and longer spring housing for the pump. The number of teeth on the pump gears, the height of the teeth gears and the diameter of the teeth gears, and the pump pick-up screen is exactly the same.

So the 80 psi pump cost them about $3 to manufacture vs the normal 60 psi pump.

I have bought just the spring housing and spring several times over the years from them. All they did was raise the control pressure before the by-pass opened up.

Tom V.

[STEELCITYFIREBIRD]

A gear pump is a positive displacement pump, that must have a precise regulator in an engine oil pump application.

So my buddy didn't understand... nor listen. Puts an arbitrary, uncalibrated spring he picked up at hardware store in his dry sump pump regulator (original spring damaged). His plan was back the adjustment all the way off and increase till acceptable.

I move undercover as he prepares to light it .

In about < 5 seconds of run time, hand still on starter button the oil filter explodes, (remote starter button in circle car to fire without driver in car.) He was COVERED in oil.

Point is a gear pump is capable of making a LOT of pressure (upwards of 3000+ psi IIRC)

The regulator sets the pump bypass point psi.(pump psi rating)
Your resultant oil pressure reading is a measurement of how much restriction/leakage there is in your engines oil system.

Max pressure is pretty much limited to what your regulator is set at.
Resultant pressure is a measure of restriction.

Longer spring is likely for more spacing between the spring coils, eliminate coil bind in high bypass conditions, limit over-pressure spikes, more precise control at higher psi/rpm situations.

HTH and makes sense.

[grandam1979]

We just got a new 60 psi pump from butler and in the box is a shin that if you want 70 psi add the shin.

[STEELCITYFIREBIRD]

Originally Posted by grandam1979

We just got a new 60 psi pump from butler and in the box is a shin that if you want 70 psi add the shin.

How thick is it?

[Steve C.]

Related....

https://forums.maxperformanceinc.com...09#post4317909

And from a different thread....


"a .060 shim will raise it about 10 psi."
Pontiac Dude


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[lust4speed]

Except I've used a .035" shim to get 70psi with 10/30w oil.

First question should be whether there is really a need for over 60 psi, and if RPM isn't going to exceed 6,000 RPM then the additional pressure is probably a detriment and causing unnecessary stress on the distributor gear.

[Steve C.]

In addition to the different threads and comments I've seen other numbers mentioned for the thickness.


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[Cliff R]

Even on the highest output full race engines I've done we've used the stock Melling pump with 60psi spring. Never a single issue with these engines even spinning them past 7000rpms.

The key to success is in the short block preparation and parts used. Good rods that don't go out of round at high RPM's/heavy load and crank and block work that are spot on for fit and finish.

We do the same with our SBC engines, even the high RPM circle track ones we've done for local racers. A stock 40lb standard volume pump is all that we use here, extra volume and pressure just rob power and wear out the distributor gear quicker. Plus you put extra stress on the pump drive (I've seen a few shear off) and timing set.......FWIW.....Cliff

[Steve C.]

This is a good read:


https://www.hotrod.com/articles/hppp...-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 valvesprings 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."



.

[Steve C.]

"I have had 2 Butler Pro Pumps and had issues with both. After doing a take apart study on the pumps, I found that many of the "modifications" either did not exist OR were counter productive to mitigating cavitation or high flow. After many discussions with David Butler, he agreed with my synopsis. I sent him a comprehensive write up. Butler has contacted their pump supplier and I believe Butler is in discussions with Mark Luhn to start carrying his pumps due to Mark's higher quality pumps that DO include REAL upgrades."


Source: http://forums.maxperformanceinc.com/...=807179&page=2

Post number 28



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[Tom Vaught]

"Mark Luhn" has probably one of the best MODIFIED "Melling type" Oil Pumps out there.

The Pumps are based off of many discussions with different Oil Pump Engineers and suggestions from OEM Pump Designers for Ford and Aston Martin Engineers.

His latest Oil Pump Pick-up design is very impressive.

If I remember correctly, his pumps were on Mike Leech's Engines at one time and worked well even at lower controlled oil pressures due to the better pick-up design.

Trying to run a mile with your nose plugged up is similar to running a oil pump with a reduced oil inlet design on a very high rpm large stroke engine. A 6000 rpm engine might live a very long time with a stock design pick-up and the right oil viscosity.

Tom V.

[Formulas]

Still have not seen a detailed picture and plausible explanation of the dreaded bearing wash phenom

[Steve C.]

Picture of Mark's new pick up design....

http://www.pontiaczone.com/forum/att...7&d=1556417278


LUHN PERFORMANCE

http://www.luhnperformance.com/pontiac.html




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[slowbird]

I wonder why Luhn did a redesign on the pickup, something wrong with the other design?

[Dragncar]

40lb pump, 60lb pump, 80lb pump. Same pump. Different relief systems.

[Dragncar]

Originally Posted by slowbird

I wonder why Luhn did a redesign on the pickup, something wrong with the other design?

Yes, the diameter of the stock, Canton and Morroso pickups can not keep up with sudden increases in needed pressure/volume. It catches up, but there is a lag and no one wants that.
So they went to one closer to 1" vs one a little ever 1/2" I.D.

I am building and modifying one with a "in-between" diameter pickup per Luhn's instructions. I have a thread on it. Waiting to get my short block from machine shop so I can finish. Will post pics.
The size I am going to is larger. But to go all the way to the 1" O.D. size tube they use requires milling off that part of the pump and using their bolt on adapter.
Oh, and the size and shape of the Canton pickup does not help anything either. Luhn said you are better off with a OEM style pickup.

[Steve C.]

"I wonder why Luhn did a redesign on the pickup, something wrong with the other design?"

As I understand it the 'new' design pick up pictured above is a shorter length for use on a oil pan depth similar to stock. His other design pickup (with tube and cone shape) as shown on the website link is still used on the highly modified oil pumps and for deeper oil pans. Again, as I understand it, That said, Dragncar is more up to date on his pick up designs.

And note the different oil pump pictured above compared to the units pictured on his website linked.


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[Stan Weiss]

Remember if you are running a 60 psi oil pump and hot your engine does not see 60 psi then changing or shimming the spring will not help increase oil pressure. Many years ago when I was running Aluminum rods in a SBC. Because larger rod side clearances I would run a high volume oil pump.

Stan