Big Block Oil Pump Spring Change

coloradodave · Oct 3, 2020

BSB67 said:
only assuming that the low oil pressure is due to the relief valve being open, which I've never seen to be the case. If the oil pressure is low at idle the spring wont help. If its low at 40 mph because the relief valve is open, a stiffer/longer/shimmed spring would help

That's not been my experience in all cases. I, like some other members, have an adjustable spring cap on my oil pump. I can dial in pretty much any idle oil pressure I want by increasing or decreasing the tension on the relief spring. The change in tension affects the pressure all the way up the rpm range. I will concede that if the low idle pressure is caused by excessive bearing clearances or worn out pump gears, the tension change won't help.

Dipstick · Oct 3, 2020

There's some misunderstanding about the function of the pressure relief valve, the valve can be completely closed and still have low pressure due to the volume being consumed by wide clearances due to wear.

I'll wager the OP has a volume problem which shows up as a pressure drop. No spring involved. In this case a high-volume pump will increase the volume and, therefore, the pressure.

MOPOWER871 · Oct 3, 2020

Milodon

CHRYSLER OIL PRESSURE REGULATOR
Permits oil pressure adjustment externally even when the engine is running. Very valuable asset for dialing-in desired oil pressure, for compensating for low oil pressure on street application or excessively high oil pressure on the track (more than 75 PSI hot is usually unecessary and uses extrahorsepower to drive).

Chrysler Wedge and 426 Hemi #21225 #21460 #21461 #21462 #21463 #21464 #21465

21550

oldbee · Oct 3, 2020

Heard of those years ago, never tried one though. Yeah, a big drop in pressure signals something else.

coloradodave · Oct 3, 2020

A good primer on this subject: https://www.chevyhardcore.com/tech-...ction-is-high-pressure-or-high-volume-better/

coloradodave · Oct 3, 2020

For those interested: 440source.com

#200-1093 Adjustable Oil Pressure Regulator
Our new adjustable oil pressure relief valve is a great accessory for your big block Mopar. You can use this to adjust your oil pressure where you like it (within a reasonable range), even while the engine is running!
In Stock
$28.95

RRDon · Oct 4, 2020

Wow, lots of good info here. I changed the spring to a Mopar heavy duty 'black' spring and my oil pressure increased over 15 psi across the rpm range. Doesn't seem to matter much cold or hot. But cold was a few pounds more. It's an easy upgrade if you'd like to see a bit more oil pressure. Assuming of course, as some of you have rightly pointed out, nothing else causing the problem.

Challenger340 · Oct 4, 2020

I must be missing something here ?

If the Oil Pressure 'relief'..... is only supposed to "open" and relieve excess Oil Pressure once the Oil System Oil Pressure reaches the target maximum Oil Pressure(usually @ higher rpm)
then praytell...
how the heck is increasing the Relief Spring 'pressure' going to increase Idle Oil Pressure when the Relief Valve is still closed as it should be at IDLE ?

Just say'in here...
IMO, if you have a Low Oil Pressure problem at IDLE ?
You may be better to consider thicker Oil than chasing a stiffer Oil Pressure relief Spring ?

RRDon · Oct 4, 2020

Challenger340 said:
I must be missing something here ?

If the Oil Pressure 'relief'..... is only supposed to "open" and relieve excess Oil Pressure once the Oil System Oil Pressure reaches the target maximum Oil Pressure(usually @ higher rpm)
then praytell...
how the heck is increasing the Relief Spring 'pressure' going to increase Idle Oil Pressure when the Relief Valve is still closed as it should be at IDLE ?

Just say'in here...
IMO, if you have a Low Oil Pressure problem at IDLE ?
You may be better to consider thicker Oil than chasing a stiffer Oil Pressure relief Spring ?

All I know is that it worked. It was recommended to me by some long time Mopar friends of mine who did the same thing at different times over the years and got the same desired results.

threewood · Oct 4, 2020

dadsbee said:
Hope it helps, but I doubt it's a tired spring! That said, I've been running my Bird with less than 10PSI for 30 years.. zero knocks and just like the EverReady bunny !

Factory oil pumps have approximately 10psi per 1k rpm. My 440 is the same way. 10psi at 800rpms, goes up to 50 psi under throttle. No issues and the motor seems happy.

dadsbee · Oct 4, 2020

threewood said:
Factory oil pumps have approximately 10psi per 1k rpm. My 440 is the same way. 10psi at 800rpms, goes up to 50 psi under throttle. No issues and the motor seems happy.

Nah, I'm lucky to have 10 at any time in the Bird... and it hasn't seemed to hurt anything in 30 some years. Tried a new pump way back then, same thing. My Bee's 383 has 50psi at start up, 30 idling hot and 60 running on 10W30, same as it has since it was rebuilt in 1988. Also never an issue with it. Mind you I pound on the Bee with the 4 gear a bit harder than the Bird's 440 gets run with the automatic.

RRDon · Oct 4, 2020

I was seeing about 10 psi at idle and 45 - 50 max at higher rpms. It seemed to be a bit lower than previously noted so I tried the new spring and now it's 25 psi or more at idle and almost 70 max at higher revs. Note, my idle is about 900 - 1000 because of the cam. (That's how the engine came when I bought it)

oldbee · Oct 4, 2020

More spring pressure stops the relief valve from moving rearward to relieve the pressure. C'mon guys look & think a little bit. (It's hard for to visualize stuff sometimes also)

Big Block Oil Pump Spring Change

coloradodave

FBBO Gold Member

Dipstick

Well-Known Member

MOPOWER871

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oldbee

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coloradodave

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coloradodave

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RRDon

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Challenger340

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RRDon

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threewood

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dadsbee

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RRDon

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oldbee

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