Shimming oil pump psi spring?
June 15th, 2016, 12:18 PM
#1
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Join Date: Jul 2014
Location: Imlay City, Michigan
Posts: 381
Shimming oil pump psi spring?
Hi,
I'm freshing up a 330 that has 50,000 on it and thru my searches I see a lot of mentions about shimming the pressure spring one post list .080 another says .250, should I consider doing this an if so how much?
65 330 4v st300 3:23 gears
Regards,
I'm freshing up a 330 that has 50,000 on it and thru my searches I see a lot of mentions about shimming the pressure spring one post list .080 another says .250, should I consider doing this an if so how much?
65 330 4v st300 3:23 gears
Regards,
June 16th, 2016, 12:27 PM
#3
4 Barrels of Laughs
Join Date: Jun 2016
Location: I moved to pittsburgh so I can be near Primantis
Posts: 405
do you have a pressure problem? by the time you drill into the pump, you might as well replace the spring.
if you are low on pressure cuz the motor is a little loose inside, a few extra psi cannot hurt but for the labor involved replace the pump. I would not use the hi-vol pump unless you uprate the oil pan to 6-7qt, oldses are good at putting all 5 quarts in the heads...
But anytime you are touching springs, its a bandaid at best. you can, while in the car, put in new rods and mains, use std size, who cares about the wear, std size bearings will be better than what you got - cheap easy fix!
if you must shim it, a 1/4-20 nut in spirit if not exact size seems to work well
if you are low on pressure cuz the motor is a little loose inside, a few extra psi cannot hurt but for the labor involved replace the pump. I would not use the hi-vol pump unless you uprate the oil pan to 6-7qt, oldses are good at putting all 5 quarts in the heads...
But anytime you are touching springs, its a bandaid at best. you can, while in the car, put in new rods and mains, use std size, who cares about the wear, std size bearings will be better than what you got - cheap easy fix!
if you must shim it, a 1/4-20 nut in spirit if not exact size seems to work well
June 17th, 2016, 03:15 AM
#4
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Join Date: Jul 2014
Location: Imlay City, Michigan
Posts: 381
Hi all,
No known issues with the oil psi, just thinking since I have the engine on a stand for resealing and repainting now would be a good time to do this mod, the car ran fine just maybe looking for a little insurance to prevent any future issues.
Regards,
No known issues with the oil psi, just thinking since I have the engine on a stand for resealing and repainting now would be a good time to do this mod, the car ran fine just maybe looking for a little insurance to prevent any future issues.
Regards,
June 17th, 2016, 07:25 AM
#7
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
I think the important point to be made is that shimming the pump relief spring will increase the maximum pump pressure, but will not in any way increase pump output.
In practice, this means that when the engine first starts up cold, the pressure will be higher than it was before, but as soon as the engine warms up, it will return to where it's always been.
As noted above, if you do want to do it, a ¼-20 or an M6 nut will be just about perfect.
- Eric
In practice, this means that when the engine first starts up cold, the pressure will be higher than it was before, but as soon as the engine warms up, it will return to where it's always been.
As noted above, if you do want to do it, a ¼-20 or an M6 nut will be just about perfect.
- Eric
June 17th, 2016, 09:20 AM
#9
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Join Date: Jul 2014
Location: Imlay City, Michigan
Posts: 381
Hi,
Doing the timming chain and converting to adjustable rockers, new valve seal while I'm there, been reading a lot on this and other Oldsmobile sites and figured I would ask.
Regards,
Doing the timming chain and converting to adjustable rockers, new valve seal while I'm there, been reading a lot on this and other Oldsmobile sites and figured I would ask.
Regards,
June 17th, 2016, 05:35 PM
#10
Registered User
Join Date: Dec 2011
Posts: 7,286
"In practice, this means that when the engine first starts up cold, the pressure will be higher than it was before, but as soon as the engine warms up, it will return to where it's always been. "
==================
The purpose of the pressure relief valve is to limit the maximum pressure at the pump output.
Whenever the pump's output exceeds the amount that is flowing thru the engine, the relief valve opens and dumps the excess back to the inlet.
The pump is geared to the crankshaft and produces more and more flow with increasing RPM.
The oil flow demand thru the engine is more or less constant. Not so RPM-dependent.
At idle, the oil pump produces little flow, not enough to unseat the relief valve, thus the pressure may be as low as 7 before the light switch activates.
As RPM increases above idle, pump output increases, and attempting to squeeze more oil thru the same passages causes the system pressure to increase. At some point, the flow produced exceeds that able to move thru the engine, even at the 60 psi or whatever the spring is set to. Then, the relief valve opens. Above that RPM, the system pressure remains constant at the relief valve setting, since flow capacity exceeds demand.
Among the factors affecting the point at which the relief valve opens are oil viscosity, temperature [which affects oil viscosity], and the relief valve spring setting.
Bear in mind too that increasing the load on the oil pump whether by the longer gears of the HV pump or by the higher pressure setting by means of spring alteration, will place more load on the oil pump drive rod, the gears, the cam, the cam drive sprockets, etc. And, that load costs HP to operate, even if it is only pressurizing the oil and dumping it across the relief valve.
==================
The purpose of the pressure relief valve is to limit the maximum pressure at the pump output.
Whenever the pump's output exceeds the amount that is flowing thru the engine, the relief valve opens and dumps the excess back to the inlet.
The pump is geared to the crankshaft and produces more and more flow with increasing RPM.
The oil flow demand thru the engine is more or less constant. Not so RPM-dependent.
At idle, the oil pump produces little flow, not enough to unseat the relief valve, thus the pressure may be as low as 7 before the light switch activates.
As RPM increases above idle, pump output increases, and attempting to squeeze more oil thru the same passages causes the system pressure to increase. At some point, the flow produced exceeds that able to move thru the engine, even at the 60 psi or whatever the spring is set to. Then, the relief valve opens. Above that RPM, the system pressure remains constant at the relief valve setting, since flow capacity exceeds demand.
Among the factors affecting the point at which the relief valve opens are oil viscosity, temperature [which affects oil viscosity], and the relief valve spring setting.
Bear in mind too that increasing the load on the oil pump whether by the longer gears of the HV pump or by the higher pressure setting by means of spring alteration, will place more load on the oil pump drive rod, the gears, the cam, the cam drive sprockets, etc. And, that load costs HP to operate, even if it is only pressurizing the oil and dumping it across the relief valve.
June 19th, 2016, 10:09 AM
#11
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Join Date: Jun 2016
Location: I moved to pittsburgh so I can be near Primantis
Posts: 405
I was forced to spend a day on my boat but thot I would add this when I got back, entitled 'what is oil pressure and why do you care?'
Question: how much oil does and oil pump pump thru the engine?
Answer: Almost none.
And oil pump only presents fluid under pressure at a pipe, no more no less, it is up to the engine the allow it in. Correction, it is up to the engine to DRAW it in.
I would bet that many reading this have re-bearing-ed a motor, filled it with oil, and stuck an oil pump drive appliance of sorts down the dizzy hole with a drill, cranked it up (preferably in the correct direction), felt the load increase, smiled, put together the motor, started it and wiped out mains 1,3 and rods 1,2,3,4.
Why? because without turning the motor over, little if any oil actually got into any bearings apart from maybe some of the mains. When a start did occur and oil started flowing, the assembly lube was exhausted before the circuit gave any oil to the bearings the farthest away.
So what really goes on inside?
You have probably all seen at your favorite auto parts store the lucas oil display there, these gears can be turned and the lucas oil 'climbs' the 3-4 gears in greater quantities than the non lucas oil. This display would also work, albeit less dramatically, if smooth wheels were used. oil will cling to a moving surface that passes over it and allow itself to be transported away where it later falls off. This is how a bearing surface lubes itself. Its called hydrodynamic lubrication and it is how MOST oiled surfaces in machinery work. Consider if you will large steam locos when the engineer would 'oil around' at each water or whatever stop.
The crank is presented oil and the main saddles where the upper bearing has a hole in it. As the crank spins by, it quickly accelerates the oil touching it away which then oozes outwards in a V shape until it flings off. The desired effect is oil at the saddle feed is constant and as it is fed, accelerated and flung, it is constantly replaced.
No more, no less and look how long main bearings last. And I should mention, this effect is directly affected by RPM (more rpm means more oil needed at the saddle). A pump that produces flow, not so much pressure, will suffice here. Honda is real good at this (more later)
And, the upper half of the main bearing shell (at least, oft the lower as well) has an annular groove.
Why?
If you have seen a crank, you know that oil holes are drilled from the main journal to the connecting journal. Well that makes sense, oil is picked up from the annular grove and flows into the drilled oil passage.
BUT!
the crank is rotating. as the oil enters the throw, it is accelerated, GREATLY towards the rod journal. It is a very easy set of calculations to determine the mass of the oil in the passage at any time, the angular velocity of the crank journal spinning and work it out to the force, aka PSI that the oil in the journal presents itself to the rod bearing. I guarantee you, it is far far higher than any oil pump could do.
Why? because the upper shell half of the big end bearing sustains the most load of any lubricated surface in a motor. The explosion in the cylinder forces the only movable part (piston) downward with a force described as Fcos(theta). The hole in the con rod journal is cleverly timed to produce fresh oil at the 'point of attack'.
And, the oil must leak out of the bearing at TDC with enough force to splash under the piston (cooling it), ooze thru the oil ring to lubricate the cylinder walls and ooze thru a hole to lube the wrist pin.
Which all leads us to a set of questions and facts to consider in your oiling system.
Fact: Aside from contact transfer of heat being next to a warm cylinder block, how is oil MOSTLY heated?
a - by pumping it
b - by presenting it to moving crank surfaces which accelerate it
c - by shooting it on the underside of a hot piston.
Question: does increasing pump outlet pressure increase flow?
Answer: yo absolutely. For any fixed pipe the equations to calculate turbulent and laminar flow rates according to pressure are easily doable. For those dealing with EFI applications, and you increase the capability of the motor, if you dont have a set of higher 'pound' injectors laying around, you simply increase fuel pressure a few pounds - its like going up a size or two.
Question: can you oil starve a motor with adequate pressure?
Answer: yo absolutely. If the pump has good output, but the main clearances are loose and too much oil gets past the mains, there may not be enough fluid for the crank throws to be accelerated into the con rods.
As I had said earlier, a pump shim is a bandaid at best. IF you have the pump in hand, how hard is it to replace it, when the $$ consideration is removed? if you have a loose engine, just replacing the bearings with new, standard size is an improvement over what you have and will often grant you another 50K of operation.
The thing about honda: honda learned years ago, mostly used in motorcycles that flow oiling is more important than pressure oiling, they will allow the centrifugal force to pressurize the rod surfaces. And to go one further, in at least the V4 racing motors, they designed the oil system to DISENGAGE the oil pump at high rpm as the fluting in the hollow crank and this whole 'oil sticks to stuff that moves by' made it a natural oil pump. I hear it was worth 5hp at race speeds.
Now granted in the last 25 years 90% of my experience is with SBC and Ford v8 oil systems, fords - almost never have oil starvation problems in the windsor motors and the 385 motors. Chevy oil system is bulletproof but has maddeningly small oil passages. The 'smokey yunick' rule of thumb was 10psi per 1000 rpm to feed the increased consumption rates at speed.
I do note, from my book that I do have, that olds requires a rather substantial oil PSI at a rather low rpm - I would assume from the large bearings sizes and an oil system which essentially stopped development in the 60's. Choose your steps wisely, there aint many spare parts to be had.
Lastly, you start the motor and it has 50-60psi at cold idle, but at hot idle its 20. is something wrong? Recall what I said above, until the motor requires and indeed, takes the oil from the pump, pressure will be also dependent on viscosity. cold oil is more viscous than warm and when warm, meaning the oil will flow no better, it will in fact experience the maximum flow that it can, rpm based, depending on pump pressure.
I would find it unlikely that any non race motor, and likely any olds motors NEED the advantage of a hi vol pump. To truly make use of it and the headache that brings, you would have a motor with fully filleted race bearings, high rpms and higher than normal main journal clearances.
Question: how much oil does and oil pump pump thru the engine?
Answer: Almost none.
And oil pump only presents fluid under pressure at a pipe, no more no less, it is up to the engine the allow it in. Correction, it is up to the engine to DRAW it in.
I would bet that many reading this have re-bearing-ed a motor, filled it with oil, and stuck an oil pump drive appliance of sorts down the dizzy hole with a drill, cranked it up (preferably in the correct direction), felt the load increase, smiled, put together the motor, started it and wiped out mains 1,3 and rods 1,2,3,4.
Why? because without turning the motor over, little if any oil actually got into any bearings apart from maybe some of the mains. When a start did occur and oil started flowing, the assembly lube was exhausted before the circuit gave any oil to the bearings the farthest away.
So what really goes on inside?
You have probably all seen at your favorite auto parts store the lucas oil display there, these gears can be turned and the lucas oil 'climbs' the 3-4 gears in greater quantities than the non lucas oil. This display would also work, albeit less dramatically, if smooth wheels were used. oil will cling to a moving surface that passes over it and allow itself to be transported away where it later falls off. This is how a bearing surface lubes itself. Its called hydrodynamic lubrication and it is how MOST oiled surfaces in machinery work. Consider if you will large steam locos when the engineer would 'oil around' at each water or whatever stop.
The crank is presented oil and the main saddles where the upper bearing has a hole in it. As the crank spins by, it quickly accelerates the oil touching it away which then oozes outwards in a V shape until it flings off. The desired effect is oil at the saddle feed is constant and as it is fed, accelerated and flung, it is constantly replaced.
No more, no less and look how long main bearings last. And I should mention, this effect is directly affected by RPM (more rpm means more oil needed at the saddle). A pump that produces flow, not so much pressure, will suffice here. Honda is real good at this (more later)
And, the upper half of the main bearing shell (at least, oft the lower as well) has an annular groove.
Why?
If you have seen a crank, you know that oil holes are drilled from the main journal to the connecting journal. Well that makes sense, oil is picked up from the annular grove and flows into the drilled oil passage.
BUT!
the crank is rotating. as the oil enters the throw, it is accelerated, GREATLY towards the rod journal. It is a very easy set of calculations to determine the mass of the oil in the passage at any time, the angular velocity of the crank journal spinning and work it out to the force, aka PSI that the oil in the journal presents itself to the rod bearing. I guarantee you, it is far far higher than any oil pump could do.
Why? because the upper shell half of the big end bearing sustains the most load of any lubricated surface in a motor. The explosion in the cylinder forces the only movable part (piston) downward with a force described as Fcos(theta). The hole in the con rod journal is cleverly timed to produce fresh oil at the 'point of attack'.
And, the oil must leak out of the bearing at TDC with enough force to splash under the piston (cooling it), ooze thru the oil ring to lubricate the cylinder walls and ooze thru a hole to lube the wrist pin.
Which all leads us to a set of questions and facts to consider in your oiling system.
Fact: Aside from contact transfer of heat being next to a warm cylinder block, how is oil MOSTLY heated?
a - by pumping it
b - by presenting it to moving crank surfaces which accelerate it
c - by shooting it on the underside of a hot piston.
Question: does increasing pump outlet pressure increase flow?
Answer: yo absolutely. For any fixed pipe the equations to calculate turbulent and laminar flow rates according to pressure are easily doable. For those dealing with EFI applications, and you increase the capability of the motor, if you dont have a set of higher 'pound' injectors laying around, you simply increase fuel pressure a few pounds - its like going up a size or two.
Question: can you oil starve a motor with adequate pressure?
Answer: yo absolutely. If the pump has good output, but the main clearances are loose and too much oil gets past the mains, there may not be enough fluid for the crank throws to be accelerated into the con rods.
As I had said earlier, a pump shim is a bandaid at best. IF you have the pump in hand, how hard is it to replace it, when the $$ consideration is removed? if you have a loose engine, just replacing the bearings with new, standard size is an improvement over what you have and will often grant you another 50K of operation.
The thing about honda: honda learned years ago, mostly used in motorcycles that flow oiling is more important than pressure oiling, they will allow the centrifugal force to pressurize the rod surfaces. And to go one further, in at least the V4 racing motors, they designed the oil system to DISENGAGE the oil pump at high rpm as the fluting in the hollow crank and this whole 'oil sticks to stuff that moves by' made it a natural oil pump. I hear it was worth 5hp at race speeds.
Now granted in the last 25 years 90% of my experience is with SBC and Ford v8 oil systems, fords - almost never have oil starvation problems in the windsor motors and the 385 motors. Chevy oil system is bulletproof but has maddeningly small oil passages. The 'smokey yunick' rule of thumb was 10psi per 1000 rpm to feed the increased consumption rates at speed.
I do note, from my book that I do have, that olds requires a rather substantial oil PSI at a rather low rpm - I would assume from the large bearings sizes and an oil system which essentially stopped development in the 60's. Choose your steps wisely, there aint many spare parts to be had.
Lastly, you start the motor and it has 50-60psi at cold idle, but at hot idle its 20. is something wrong? Recall what I said above, until the motor requires and indeed, takes the oil from the pump, pressure will be also dependent on viscosity. cold oil is more viscous than warm and when warm, meaning the oil will flow no better, it will in fact experience the maximum flow that it can, rpm based, depending on pump pressure.
I would find it unlikely that any non race motor, and likely any olds motors NEED the advantage of a hi vol pump. To truly make use of it and the headache that brings, you would have a motor with fully filleted race bearings, high rpms and higher than normal main journal clearances.
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