Any one interested in the oiling mods I did?

[Duane]

I get what your saying. My issue is I never failed the 5-6 rod bearings, and I’ve never seen anyone else. It’s always the 3-4 rods. In fact, my first 2 X block came real cheap because he kicked the 3-4 rods off both and quit racing over it. I offered to have him send them to me, and I’d fix the issues but he was done. His loss, my gain. A couple of sleeves and they went into service.

So that can’t be a velocity issue. If you’ve ever seen say...a long string of sprinklers in a field, like 30 or so where you get look at the system filling up, you’ll see the last 2 or 3 sprinkler heads and the first 20 or so will all be at full load while those at the far end that are 3-5 are the very last to get to full flow. Once they are all flowing, the nozzle is the limit. Pretty much what happens in an oiling system.

Here is a theory I have but cannot prove. Does an engine oil pump pressure feed the rod bearing or does the centrifugal force of the spinning crankshaft throw the oil in the crank oil cavity at the rod bearings. This was Sanborns theory that the slotting of main bearings gave a longer dwell time for that passage to fill up.
I ask this because I have had failed 2&4 main bearings with no sign of rod bearing damage. It was explained to me that because I did not restrict oil going to the rockers, my main bearing oil did not form hydro dynamic wedge because of inadequate pressure, yet I saw no signs of rod bearing trouble. Could it be that because the crank passage was filled but not pressurized, that centrifugal force still adequately supplied the rods?

 

[yellow rose]

I agree that gauge pressure and galley pressure may not match, but why would two identical opposing columns of oil from the same source not have the same pressure?

Because the oil coming from the pump to the filter, back in to the block, makes and vertical 90, then goes up then another 90 and then a 90 just to get to the mains.

I’m not sure where you’re going to pick up the oil to go into the front, but it will most likely have much less pressure drop than the oil coming from the main feed.

I only checked the pressure drop across the filter once and IIRC it was 8 or 10 PSI at 100 psi. So 110 in and 102 or 100 out. So I figured the pressure drop at the bearings was 20 psi or less.

I was also killing adjusters for a bit, and I was looking for solutions. One was putting direct oil into the shafts after the filter. Giant PITA and that didn’t fix the oil timing issue at the rockers.

What prompted that was I checked the pressure at the end of the shaft farthest from the feed (so the number 7 end on that side) and at a 40 psi hot idle there was only 10 psi at the end of the shaft. It was grabbing the bushing and that was why. If I had needle bearing rockers rockers that may have been ok. And I was killing adjusters.

The fix was get the idle pressure up to 60 hot and fix the oil timing issue to the adjusters. That stopped the adjuster eating and the higher line pressure kept the bushings off the shafts.

 

[yellow rose]

Here is a theory I have but cannot prove. Does an engine oil pump pressure feed the rod bearing or does the centrifugal force of the spinning crankshaft throw the oil in the crank oil cavity at the rod bearings. This was Sanborns theory that the slotting of main bearings gave a longer dwell time for that passage to fill up.
I ask this because I have had failed 2&4 main bearings with no sign of rod bearing damage. It was explained to me that because I did not restrict oil going to the rockers, my main bearing oil did not form hydro dynamic wedge because of inadequate pressure, yet I saw no signs of rod bearing trouble. Could it be that because the crank passage was filled but not pressurized, that centrifugal force still adequately supplied the rods?

You have to increase the dwell time IF the oil timing is off. That’s the band aid. Like full groove mains. You are getting oil to the rods all the time.

If you read that paper that Phreakish posted they discussed putting oil in at TDC. Or shortly after. Pretty interesting.

Again, I use the SBC a my example. They don’t need full groove mains, more dwell time or any of that, because the oil is there, full flow, full pressure at the correct time.

Obviously if the big end of the rods don’t stay round, or they have too much clearance (almost as bad as too little clearance) the pan sucks or some other issue, that system is pretty much bullet proof, even if you oil the mains after the cam the OE stuff did for decades.

EDIT: forgot to mention this question, because it has me scratching my head. The mains get oiled first. So how the mains get starved and not the rods? Or did they both get it.

I think I said this earlier but I prefer to groove the cam and restrict the oil in 2 and 4 rather than just restricting oil there. You can cut the others back more, but 2 and 4 can still get cut back quite a bit if they are getting full time oil.

 

[Duane]

Because the oil coming from the pump to the filter, back in to the block, makes and vertical 90, then goes up then another 90 and then a 90 just to get to the mains.

I’m not sure where you’re going to pick up the oil to go into the front, but it will most likely have much less pressure drop than the oil coming from the main feed.

I only checked the pressure drop across the filter once and IIRC it was 8 or 10 PSI at 100 psi. So 110 in and 102 or 100 out. So I figured the pressure drop at the bearings was 20 psi or less.

I was also killing adjusters for a bit, and I was looking for solutions. One was putting direct oil into the shafts after the filter. Giant PITA and that didn’t fix the oil timing issue at the rockers.

What prompted that was I checked the pressure at the end of the shaft farthest from the feed (so the number 7 end on that side) and at a 40 psi hot idle there was only 10 psi at the end of the shaft. It was grabbing the bushing and that was why. If I had needle bearing rockers rockers that may have been ok. And I was killing adjusters.

The fix was get the idle pressure up to 60 hot and fix the oil timing issue to the adjusters. That stopped the adjuster eating and the higher line pressure kept the bushings off the shafts.

I gotcha. Well all I can hope for is that the difference will be minimal. I opened all the rear block passages, so maybe that will reduce the difference. I will look at that rocker timing when the time comes. Thanks for teaching me about that, never looked at that ever before. Do you know if the Norris rockers also have the timing issue?

 

[Duane]

You have to increase the dwell time IF the oil timing is off. That’s the band aid. Like full groove mains. You are getting oil to the rods all the time.

If you read that paper that Phreakish posted they discussed putting oil in at TDC. Or shortly after. Pretty interesting.

Again, I use the SBC a my example. They don’t need full groove mains, more dwell time or any of that, because the oil is there, full flow, full pressure at the correct time.

Obviously if the big end of the rods don’t stay round, or they have too much clearance (almost as bad as too little clearance) the pan sucks or some other issue, that system is pretty much bullet proof, even if you oil the mains after the cam the OE stuff did for decades.

EDIT: forgot to mention this question, because it has me scratching my head. The mains get oiled first. So how the mains get starved and not the rods? Or did they both get it.

I think I said this earlier but I prefer to groove the cam and restrict the oil in 2 and 4 rather than just restricting oil there. You can cut the others back more, but 2 and 4 can still get cut back quite a bit if they are getting full time oil.

That does look like a good read. Maybe I will sign up so I can read it. I am curious lol. I am sold on the oil timing issue though.
The Chevy is different that way.

 

[yellow rose]

You have to increase the dwell time IF the oil timing is off. That’s the band aid. Like full groove mains. You are getting oil to the rods all the time.

If you read that paper that Phreakish posted they discussed putting oil in at TDC. Or shortly after. Pretty interesting.

Again, I use the SBC a my example. They don’t need full groove mains, more dwell time or any of that, because the oil is there, full flow, full pressure at the correct time.

Obviously if the big end of the rods don’t stay round, or they have too much clearance (almost as bad as too little clearance) the pan sucks or some other issue, that system is pretty much bullet proof, even if you oil the mains after the cam the OE stuff did for decades.

I gotcha. Well all I can hope for is that the difference will be minimal. I opened all the rear block passages, so maybe that will reduce the difference. I will look at that rocker timing when the time comes. Thanks for teaching me about that, never looked at that ever before. Do you know if the Norris rockers also have the timing issue?

I LOVE those rockers. The issue isn’t the rocker, it’s where Chrysler put the holes in the shafts.

I have never seen any shafts sold as W2/5 stuff that had the oil holes positioned correctly. They are actually laid out for the T/A offset.

The brand new shafts I have are wrong and need to be corrected. I wrote a long technical papers with drawing and such and Chrysler blew it off.

You can mock yours up and see what you have. I’d bet everything o have that the holes will not only be off left to right (as in the hole is too close to the rocker centerline) by .100 or so and they will be off radially. Especially when the geometry is correct.

I tried grooving the shafts but it never worked. I just blue the shafts, mock it all up and take the adjusters out and go through the feed hole to mark the shafts. Then I drill new holes in the shaft and plug the old holes with lead shot.

You do that and the adjusters will oil to well past 9k with 360 or more on the seat.

 

[Phreakish]

Pressure to the rod is both pump and centrifugal, but centrifugal dominates.

If the cam bearing is trash or using a full grooved cam, oil may "skip" the mains and go straight toward the cam/heads.There would be a lack of pressure caused by a lack of restriction down stream (cam or head). Even still, when the rod feed passage aligns with the oil feed from the block it will fill no matter what - path of least resistance. Once it's full, centrifugal effects will force it to the rods throughout the rotation.

Damage to #2 and #4 caused by the trashed bearings or full groove cam will likely not happen at high revs, but when warm and at moderate load. Without adequate pressure to build the film, the bearings will heat and fail.

So theoretically at least, it seems possible to trash the mains and not rods. High revs, however, will trash rods and likely also adjusters and pushrods (lack of dwell at the cam causing a lack of supply to the heads).

 

[gregcon]

The reason the simplified diagram is 'good' is that the remainder of the oiling system - rockers, cam bearings etc. have nothing to do with whether or not the oil is willing to take a turn to go the #4 main. That's the whole point of the question....to discuss if the 'oil will keep on truckin past #4' bit has merit or not.

You could even argue that since #4 feeds the rockers, it presents a greater loss than the mains which don't feed rockers. Therefore, the oil in the galley is more likely to seek the low pressure area and the #4 would be an 'oil hog' as compared to #3, for instance. It probably pulls more oil off the galley, not less. The problem is that it serves three masters - the mains/cam bearings/rockers - and there's not enough to go around.

So Duane says engines that run a front feed also run a rear feed. YR says they never do. You two gotta work that out lol. I'll tell you I've seen it both ways but more often it is only one. I think guys do one because it is easier, not because they've decided it's better. For the belted oil pump engine, feeding in the front is way more tidy. Plus, it was an easy mod for Chrysler to make to the block, so they did it.

If you have a single pump and you split the output into two line, then feed those two lines into the same manifold, it'll work fine....that is assuming you take some time to balance the hoses, etc. The pressure in the galley is not the same as it shows on the gauge? I fully agree....that's precisely why the double feed is good - it helps achieve the goal of balanced feed across the engine.

 

[Duane]

Pressure to the rod is both pump and centrifugal, but centrifugal dominates.

If the cam bearing is trash or using a full grooved cam, oil may "skip" the mains and go straight toward the cam/heads.There would be a lack of pressure caused by a lack of restriction down stream (cam or head). Even still, when the rod feed passage aligns with the oil feed from the block it will fill no matter what - path of least resistance. Once it's full, centrifugal effects will force it to the rods throughout the rotation.

Damage to #2 and #4 caused by the trashed bearings or full groove cam will likely not happen at high revs, but when warm and at moderate load. Without adequate pressure to build the film, the bearings will heat and fail.

So theoretically at least, it seems possible to trash the mains and not rods. High revs, however, will trash rods and likely also adjusters and pushrods (lack of dwell at the cam causing a lack of supply to the heads).

Yes that seems to be what caused my failure, to the mains while the rods were fine. I just read the oiling article that you linked to.
That is indeed a good read. Centrifugal force does indeed feed the rods, wow.

 

[Duane]

The reason the simplified diagram is 'good' is that the remainder of the oiling system - rockers, cam bearings etc. have nothing to do with whether or not the oil is willing to take a turn to go the #4 main. That's the whole point of the question....to discuss if the 'oil will keep on truckin past #4' bit has merit or not.

You could even argue that since #4 feeds the rockers, it presents a greater loss than the mains which don't feed rockers. Therefore, the oil in the galley is more likely to seek the low pressure area and the #4 would be an 'oil hog' as compared to #3, for instance. It probably pulls more oil off the galley, not less. The problem is that it serves three masters - the mains/cam bearings/rockers - and there's not enough to go around.

So Duane says engines that run a front feed also run a rear feed. YR says they never do. You two gotta work that out lol. I'll tell you I've seen it both ways but more often it is only one. I think guys do one because it is easier, not because they've decided it's better. For the belted oil pump engine, feeding in the front is way more tidy. Plus, it was an easy mod for Chrysler to make to the block, so they did it.

If you have a single pump and you split the output into two line, then feed those two lines into the same manifold, it'll work fine....that is assuming you take some time to balance the hoses, etc. The pressure in the galley is not the same as it shows on the gauge? I fully agree....that's precisely why the double feed is good - it helps achieve the goal of balanced feed across the engine.

Whether a guy feeds just one end or two would be an individual choice. I would never claim to have seen every guys engine.
But there have been two high profile posters on some of the Mopar small block oiling forums who fed both ends and claim very worthy improvements.
If you can take the time to read the oiling article that Phreakish linked us to, at some point in that article it discusses how some main bearings start getting less oil volume with the successive addition of other leakage points in the path. The only conclusion is that those additional leakage paths mess up the distribution. Pressure does not fix it, which is what I have been trying to impress on you.
That is consistent with my assessment of your drawing. You have left out almost all the leakage paths that are on the engine.
Your drawing resembles what is recommended to do to gain reliability in an extreme performance engine. It does not prove nor disprove that the sbm has distribution oiling issues.
You should submit to your oiling guy a drawing of a stock oiling system and pose the same questions about distribution, and see what he says.

 

[Duane]

Pressure to the rod is both pump and centrifugal, but centrifugal dominates.

If the cam bearing is trash or using a full grooved cam, oil may "skip" the mains and go straight toward the cam/heads.There would be a lack of pressure caused by a lack of restriction down stream (cam or head). Even still, when the rod feed passage aligns with the oil feed from the block it will fill no matter what - path of least resistance. Once it's full, centrifugal effects will force it to the rods throughout the rotation.

Damage to #2 and #4 caused by the trashed bearings or full groove cam will likely not happen at high revs, but when warm and at moderate load. Without adequate pressure to build the film, the bearings will heat and fail.

So theoretically at least, it seems possible to trash the mains and not rods. High revs, however, will trash rods and likely also adjusters and pushrods (lack of dwell at the cam causing a lack of supply to the heads).

I agree, in my mind t is just another example that pressure does not mean everything is well, and it does not mean every component has sufficient pressure and volume.
My new build will supply the top end directly from the main galley.
All my cam bearings are now restricted to 1/8, all of them!
And they will not feed oil to anything else.

 

[gregcon]

I am confident the addition of the cam bearing feeds and rocker feeds would make no difference in the 'does #4 fail to get oil because the oil won't make the turn' discussion. I can't think of any reason they would. My diagram, again, is aimed at that question alone. It's not intended to be a cover-all for the SBM oil system.

 

[Phreakish]

I am confident the addition of the cam bearing feeds and rocker feeds would make no difference in the 'does #4 fail to get oil because the oil won't make the turn' discussion. I can't think of any reason they would. My diagram, again, is aimed at that question alone. It's not intended to be a cover-all for the SBM oil system.

I hadn't looked at your diagram or the discussion behind it before, and nothing I've said is aimed at it. Your engineer friend is right of course, but if sufficient volume and pressure is available then manifold design becomes a little less critical (within reason). Some pressure differential or imbalance is likely acceptable in operation. The extent of that imbalance will only be worsened by things like cam and rocker feeds and during marginal adverse situations those flow/pressure differences due to manifold imbalance will likely determine what fails first.

So, I would tend to agree that larger main oil galley size would benefit the oiling of these engines more than anything. Increasing the passage sizes from the pickup all the way through the filter circuit and main feed back into the block would probably reap a majority of improvements available in the factory oiling scheme. Maximizing everything from the pickup to the main while minimizing (without over-restricting) everything past the mains should yield success in almost every case. Until the rods run out of oil at high revs..

I also agree that oil doesn't need to 'turn' to get to #4 - oil will 'expand' into any area where pressure is lowered. There is some momentum due to oil having mass, but it's not solid particles and it's also not a compressible fluid like air..

 

[Duane]

I am confident the addition of the cam bearing feeds and rocker feeds would make no difference in the 'does #4 fail to get oil because the oil won't make the turn' discussion. I can't think of any reason they would. My diagram, again, is aimed at that question alone. It's not intended to be a cover-all for the SBM oil system.

Gregcon just so we are clear, we are only saying that the oil has trouble turning to #4 main with a stock oiling system with a high volume pump. No one is saying that it is still a problem after you modify the system. The drawing you made should not have any trouble because the issues that would cause the velocity issue have been removed. As I posted before I have failed main bearings 2&4 even though there was plenty of volume going too them because there was not enough of a restriction in the passages feeding the rockers. Because there was no restriction, there was inadequate pressure at those two main bearings. Surely that will convince you that pressure does not fix everything.

 

[Phreakish]

Gregcon just so we are clear, we are only saying that the oil has trouble turning to #4 main with a stock oiling system with a high volume pump. No one is saying that it is still a problem after you modify the system. The drawing you made should not have any trouble because the issues that would cause the velocity issue have been removed. As I posted before I have failed main bearings 2&4 even though there was plenty of volume going too them because there was not enough of a restriction in the passages feeding the rockers. Because there was no restriction, there was inadequate pressure at those two main bearings. Surely that will convince you that pressure does not fix everything.

Pressure would fix it, because pressure is resistance to flow - if there's more pressure it's because more volume is available.

 

[Duane]

I hadn't looked at your diagram or the discussion behind it before, and nothing I've said is aimed at it. Your engineer friend is right of course, but if sufficient volume and pressure is available then manifold design becomes a little less critical (within reason). Some pressure differential or imbalance is likely acceptable in operation. The extent of that imbalance will only be worsened by things like cam and rocker feeds and during marginal adverse situations those flow/pressure differences due to manifold imbalance will likely determine what fails first.

So, I would tend to agree that larger main oil galley size would benefit the oiling of these engines more than anything. Increasing the passage sizes from the pickup all the way through the filter circuit and main feed back into the block would probably reap a majority of improvements available in the factory oiling scheme. Maximizing everything from the pickup to the main while minimizing (without over-restricting) everything past the mains should yield success in almost every case. Until the rods run out of oil at high revs..

I also agree that oil doesn't need to 'turn' to get to #4 - oil will 'expand' into any area where pressure is lowered. There is some momentum due to oil having mass, but it's not solid particles and it's also not a compressible fluid like air..

I hadn't looked at your diagram or the discussion behind it before, and nothing I've said is aimed at it. Your engineer friend is right of course, but if sufficient volume and pressure is available then manifold design becomes a little less critical (within reason). Some pressure differential or imbalance is likely acceptable in operation. The extent of that imbalance will only be worsened by things like cam and rocker feeds and during marginal adverse situations those flow/pressure differences due to manifold imbalance will likely determine what fails first.

So, I would tend to agree that larger main oil galley size would benefit the oiling of these engines more than anything. Increasing the passage sizes from the pickup all the way through the filter circuit and main feed back into the block would probably reap a majority of improvements available in the factory oiling scheme. Maximizing everything from the pickup to the main while minimizing (without over-restricting) everything past the mains should yield success in almost every case. Until the rods run out of oil at high revs..

I also agree that oil doesn't need to 'turn' to get to #4 - oil will 'expand' into any area where pressure is lowered. There is some momentum due to oil having mass, but it's not solid particles and it's also not a compressible fluid like air..

The entire second oil galley (drivers side) is filled exclusively from number 1 main. That galley also feeds 8 lifters

I hadn't looked at your diagram or the discussion behind it before, and nothing I've said is aimed at it. Your engineer friend is right of course, but if sufficient volume and pressure is available then manifold design becomes a little less critical (within reason). Some pressure differential or imbalance is likely acceptable in operation. The extent of that imbalance will only be worsened by things like cam and rocker feeds and during marginal adverse situations those flow/pressure differences due to manifold imbalance will likely determine what fails first.

So, I would tend to agree that larger main oil galley size would benefit the oiling of these engines more than anything. Increasing the passage sizes from the pickup all the way through the filter circuit and main feed back into the block would probably reap a majority of improvements available in the factory oiling scheme. Maximizing everything from the pickup to the main while minimizing (without over-restricting) everything past the mains should yield success in almost every case. Until the rods run out of oil at high revs..

I also agree that oil doesn't need to 'turn' to get to #4 - oil will 'expand' into any area where pressure is lowered. There is some momentum due to oil having mass, but it's not solid particles and it's also not a compressible fluid like air..

The entire drivers side galley that feeds 8 more lifter bores from number 1 main is missing from the drawing. The passenger side galley is not sealed on the passenger side. It still feeds the other side of the engine and 8 more lifters. How is his drawing representative of that. It's not.
Sanborn claimed to repeatedly fail number one main until he blocked the supply to the other side. That main fails from a lack of restriction. That is also what creates the velocity issue at number 4. The oil is always rushing down the freeway trying To fill 16 leaks and another entires galley and starves the first one or two.
His drawing does not show that. Imho

 

[yellow rose]

The entire second oil galley (drivers side) is filled exclusively from number 1 main. That galley also feeds 8 lifters

The entire drivers side galley that feeds 8 more lifter bores from number 1 main is missing from the drawing. The passenger side galley is not sealed on the passenger side. It still feeds the other side of the engine and 8 more lifters. How is his drawing representative of that. It's not.
Sanborn claimed to repeatedly fail number one main until he blocked the supply to the other side. That main fails from a lack of restriction. That is also what creates the velocity issue at number 4. The oil is always rushing down the freeway trying To fill 16 leaks and another entires galley and starves the first one or two.
His drawing does not show that. Imho

I totally agree with blocking ALL oil to the drivers side. That should be a given. For the same reason, I tube everything, and like gregcon if you need pushrod oiling or for some reason you want to use a hydraulic lifter you can use a hole size that isn’t big enough to lube a super tanker.

IMHO, it’s all about oil control first and timing second. I suspect even if you correct the timing and don’t clean up the oil usage you’ll still have some bearing issues if the RPM gets higher.

 

[gregcon]

The reason the driver side galley create problem is that it is fed off the right side, as noted. But that in and of itself wouldn't matter except it creates an added demand on the right side that the right side can't keep up with. I fully agree with 'cutting off' the left side....at least as far as feeding it through the long and winding path of the #1 main bearing saddle goes.

If #4 is starved because of the left side galley, it's not because of velocity but because the 'drain' imposed by the left galley prevents the right galley from maintaining pressure. When the right side's pressure sags, it might well starve #4. But the sag is from lack of pressure/volume, not because of velocity.

This says it well "Pressure would fix it, because pressure is resistance to flow - if there's more pressure it's because more volume is available."

You can't keep the pressure up if the volume sags. When you can't move enough oil, the first thing that drops is pressure. Why can't you move enough oil? Could be the pump is too small, the passages are too small, or the 'leak' is too large. But velocity? Nope.

 

[Duane]

Pressure would fix it, because pressure is resistance to flow - if there's more pressure it's because more volume is available.

Did you read the article that you posted a link too you're self?
I read it thoroughly last night and it well acknowledges that more leaks messes up the distribution. It says some bearings get more oil than others as a direct result of more and more leaks. Pressure does not always fix it.

 

[Duane]

Pressure would fix it, because pressure is resistance to flow - if there's more pressure it's because more volume is available.

Again I will say it is not a sealed brake system. There is always some flow.

 

[Phreakish]

Did you read the article that you posted a link too you're self?
I read it thoroughly last night and it well acknowledges that more leaks messes up the distribution. It says some bearings get more oil than others as a direct result of more and more leaks. Pressure does not always fix it.

That doesn't mean what I said is wrong. When leaks outrun supply, pressure drops. Upping the pressure means there's a commensurate increase in volume available.

Now, if that increase in volume still can't make up for the leak - then yeah, you still have issues.

 

[Phreakish]

Again I will say it is not a sealed brake system. There is always some flow.

Agreed. As soon as outflow exceeds inflow though the pressure will drop. It is possible that an increase in supply pressure (which occurs due to a lack of outflow *somewhere*) can overcome the drop and tread back into adequate volume territory.

It is also possible that the increase in pressure won't be sufficient. It's also possible to a have a system where the supply pressure CANNOT REACH the threshold needed to supply the necessary volume at some downstream location.

None of these things is contradictory. There are specifics within the system that matter. As YR (And I think everyone else) has stated: pressure at the sending unit location is not necessarily pressure everywhere. Mostly because of the constant flow issue (because in a static system, Pascal's rule would apply).

 

[Duane]

The reason the driver side galley create problem is that it is fed off the right side, as noted. But that in and of itself wouldn't matter except it creates an added demand on the right side that the right side can't keep up with. I fully agree with 'cutting off' the left side....at least as far as feeding it through the long and winding path of the #1 main bearing saddle goes.

If #4 is starved because of the left side galley, it's not because of velocity but because the 'drain' imposed by the left galley prevents the right galley from maintaining pressure. When the right side's pressure sags, it might well starve #4. But the sag is from lack of pressure/volume, not because of velocity.

This says it well "Pressure would fix it, because pressure is resistance to flow - if there's more pressure it's because more volume is available."

You can't keep the pressure up if the volume sags. When you can't move enough oil, the first thing that drops is pressure. Why can't you move enough oil? Could be the pump is too small, the passages are too small, or the 'leak' is too large. But velocity? Nope.

Please reread your last post. On one hand your acknowledging that the drivers side galley creates a problem,but your sayings that it's because the passenger sides cannot keep up. If it could not keep up you would not have any oil pressure. It keeps up fine. The pump puts out more than the leaks. But it keeps up with rapid flow. With a high volume hi pressure pump it really flows well. The flow in the galley or the speed of it is the problem. It has to rush to all those leaks to maintain pressure. Then you say when you cannot move oil fast enough you lose pressure. That's precisely what I have been trying to say. The pump is moving the oil extremely rapidly to get to all the leaks to maintain pressure. In the process it leaves number four a little shy.

 

[Duane]

Agreed. As soon as outflow exceeds inflow though the pressure will drop. It is possible that an increase in supply pressure (which occurs due to a lack of outflow *somewhere*) can overcome the drop and tread back into adequate volume territory.

It is also possible that the increase in pressure won't be sufficient. It's also possible to a have a system where the supply pressure CANNOT REACH the threshold needed to supply the necessary volume at some downstream location.

None of these things is contradictory. There are specifics within the system that matter. As YR (And I think everyone else) has stated: pressure at the sending unit location is not necessarily pressure everywhere. Mostly because of the constant flow issue (because in a static system, Pascal's rule would apply).

Agreed, your last paragraph: there are specifics involved within the system. None of those specifics are in Gregcons drawing. The system he drew would have no issues, but that not what the discussion was about. It was about the problems of the stock system in a performance situation. Gregcon is assuming that those specifics in the sbm would have no effect on the oil distribution in his drawing. I disagree.

 

[Phreakish]

Agreed, your last paragraph: there are specifics involved within the system. None of those specifics are in Gregcons drawing. The system he drew would have no issues, but that not what the discussion was about. It was about the problems of the stock system in a performance situation. Gregcon is assuming that those specifics in the sbm would have no effect on the oil distribution in his drawing. I disagree.

I don't think so.
@gregcon is only questioning the one claim that oil 'shoots past' #4 or #2 main - it does not and could not.
I don't think he disagrees that there are other issues or reasons that the pressure at a particular main bearing may drop and he obviously stated that there are shortcomings in the oiling system which could be attributed to uneven oil distribution.

One other question he asked, which I thought was pertinent, was why enlarging the feed to the main would do any good since there's only so much oil available at the primary galley and the primary is already undersized. That increasing the ability to outflow really isn't going to help much since the supply side is already restricted. I think he made a good point with that, and since enlarging the primary feed is tough, double-feeding the primary would be the next best thing. I don't think he's wrong based on all the info that's been discussed and shared. Would it be the best way? I dunno, I haven't done oil system development on small block chryslers. But it's definitely A way to do it.