Oil Drain backs

CDMBill wrote:

Doug Rahn wrote:I should also add that I have seen a correlation between vacuum and oil pressure on my 598. I have a Peterson Wet/Vac pump and on my data logger when the vacuum would reach 12", I could see the oil pressure fluctuating. So I keep mine at 8/9", no issues.

I also have the Peterson WetVac v2 on my 598. I have Star Machine adjustable vacuum break on the VC set to 12". I don't see the flutter issue you report. What size feedline to the pump section do you use? I have a 1" (-16) per Peterson's advice)

I also have a -16 on the suction side and I have Petersons adjustable vacuum breaker mounted in the tunnel ram valley.

With all the clearances you're quoting you're pumping a ton of oil.
Lifters should be at .002 max. Rods .0025. Mains are OK.
Oil pressure fluctuation due to vacuum is a gauge thing, not a system thing. Have you tried running ti without the vac pump hooked up? A vac pump usually minimizes windage issues by reducing atmosphere in the crank case. I would pull all the vacuum you can. It won't hurt anything.
Drain backs are a great idea. There is no downside to them. Anything you can do to get the oil back in the pan asap is a good thing.

Scott Foxwell wrote:With all the clearances you're quoting you're pumping a ton of oil.
Lifters should be at .002 max. Rods .0025. Mains are OK.
Oil pressure fluctuation due to vacuum is a gauge thing, not a system thing. Have you tried running ti without the vac pump hooked up? A vac pump usually minimizes windage issues by reducing atmosphere in the crank case. I would pull all the vacuum you can. It won't hurt anything.
Drain backs are a great idea. There is no downside to them. Anything you can do to get the oil back in the pan asap is a good thing.

Thank you Scott, you are not the first to say my clearances are well big.

Yes we have ran it without the vac on it and experience a 5-8 psi uptick in oil pressure both on the dyno and in the truck. Being we are noticing the issue on 2 different gauges I feel it is more than a gauge thing. Though I understand what you are saying.

The engine picks up so much average and peak numbers that I keep the vac relief screwed all the way in for max vacuum. We kept a close eye on the filter and now that it is torn down have virtually no damage do to lack of oil so I plan to continue this practice. Would actually like to plumb the vac pump with no relief to get max possible. This is why I would like to do the external drain backs, just unsure of the correct, or optimal placement.

Doug Rahn wrote:

CDMBill wrote:

Doug Rahn wrote:I should also add that I have seen a correlation between vacuum and oil pressure on my 598. I have a Peterson Wet/Vac pump and on my data logger when the vacuum would reach 12", I could see the oil pressure fluctuating. So I keep mine at 8/9", no issues.

I also have the Peterson WetVac v2 on my 598. I have Star Machine adjustable vacuum break on the VC set to 12". I don't see the flutter issue you report. What size feedline to the pump section do you use? I have a 1" (-16) per Peterson's advice)

I also have a -16 on the suction side and I have Petersons adjustable vacuum breaker mounted in the tunnel ram valley.

I am thinking a -16 may be added to mine as well just to ensure, though SCP does say -12 is adequate

EverySparePenny wrote:

Scott Foxwell wrote:With all the clearances you're quoting you're pumping a ton of oil.
Lifters should be at .002 max. Rods .0025. Mains are OK.
Oil pressure fluctuation due to vacuum is a gauge thing, not a system thing. Have you tried running ti without the vac pump hooked up? A vac pump usually minimizes windage issues by reducing atmosphere in the crank case. I would pull all the vacuum you can. It won't hurt anything.
Drain backs are a great idea. There is no downside to them. Anything you can do to get the oil back in the pan asap is a good thing.

Thank you Scott, you are not the first to say my clearances are well big.

Yes we have ran it without the vac on it and experience a 5-8 psi uptick in oil pressure both on the dyno and in the truck.  Being we are noticing the issue on 2 different gauges I feel it is more than a gauge thing.  Though I understand what you are saying.

The engine picks up so much average and peak numbers that I keep the vac relief screwed all the way in for max vacuum.  We kept a close eye on the filter and now that it is torn down have virtually no damage do to lack of oil so I plan to continue this practice.  Would actually like to plumb the vac pump with no relief to get max possible.  This is why I would like to do the external drain backs, just unsure of the correct, or optimal placement.

Best placement is somewhere in the back corner of the head where you can catch the oil before the drain back in the head. I don't know how much valve cover rail you have to work with but here's what I did on one of my BB Chev's; It's a -8 line with a -8 x 3/8 pipe fitting. It's a big hole to drill and tap. Any smaller fitting and it;s going to be necked down smaller than the -8 line (1/2").

Somewhere around here: (Pic is off the internet. Don't know who's engine it is.)



Example:









I'm sure there are other opinions on where and how to do this, just giving you an idea of what I did. You want to make sure the oil returns into the pan at a main bulkhead, not where it can be interfered with by the rotating assy.

Scott, do you feel it would be best the return enter the pan under the windage tray then?

Ya I would have to look at my heads again, I don't think I have that much meat to work with before the OEM drain pool area

EverySparePenny wrote:Scott, do you feel it would be best the return enter the pan under the windage tray then?

Ya I would have to look at my heads again, I don't think I have that much meat to work with before the OEM drain pool area

Yes, under the tray if possible. You might have to get creative with the drain back location in the head. Honestly, though, it doesn't sounds like that's your problem if that much of an oil level change in the pan didn't change anything.

Scott Foxwell wrote:

EverySparePenny wrote:Scott, do you feel it would be best the return enter the pan under the windage tray then?

Ya I would have to look at my heads again, I don't think I have that much meat to work with before the OEM drain pool area

Yes, under the tray if possible. You might have to get creative with the drain back location in the head. Honestly, though, it doesn't sounds like that's your problem if that much of an oil level change in the pan didn't change anything.

That's what I'm affraid of

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EverySparePenny wrote:

Scott Foxwell wrote:

EverySparePenny wrote:Scott, do you feel it would be best the return enter the pan under the windage tray then?

Ya I would have to look at my heads again, I don't think I have that much meat to work with before the OEM drain pool area

Yes, under the tray if possible. You might have to get creative with the drain back location in the head. Honestly, though, it doesn't sounds like that's your problem if that much of an oil level change in the pan didn't change anything.

That's what I'm affraid of

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Maybe spend the time to enlarge and "blue print" the drain backs in the heads, and clean up where they meet the block. There is a lot of improvement that can be made there.

E.S.P. : Installing external oil drain backs has some up side and no down side. But, don't over look the obvious.

1] Pump pressure section is bigger than it needs to be. Pump drive ratio is higher than it should be, especially given the time the engine is at high RPM. The thing is trying to pump too much oil and the "too much" oil is being offered an escape route....see #2.

2] {A} The lifter bushings really do need to be replaced. The .041" hole in them is about twice the size they need to be if a guy was trying to restrict the oil.
{B} """"""""""""""""""""""""""""""""""""""""""""""""""" .0035" lifter to bushing clearance is a huge leak. Like Scott said, ~.002" works.

3] I'm thinking you said the rod bearing clearance is .0035".....if so....it could be less but, given the 2-1/2" rod journal and the engines RPM range I'd rather see .003" than .0025" .

Lem Evans wrote:E.S.P. : Installing external oil drain backs has some up side and no down side. But, don't over look the obvious.

1] Pump pressure section is bigger than it needs to be. Pump drive ratio is higher than it should be, especially given the time the engine is at high RPM. The thing is trying to pump too much oil and the "too much" oil is being offered an escape route....see #2.

2] {A} The lifter bushings really do need to be replaced. The .041" hole in them is about twice the size they need to be if a guy was trying to restrict the oil.
{B} """"""""""""""""""""""""""""""""""""""""""""""""""" .0035" lifter to bushing clearance is a huge leak. Like Scott said, ~.002" works.

3] I'm thinking you said the rod bearing clearance is .0035".....if so....it could be less but, given the 2-1/2" rod journal and the engines RPM range I'd rather see .003" than .0025" .

Thank you Lem

I will definitely be playing with #1.

#2 I might be able to partially tackling if I can find a tighter fitting set of lifters than the Comps. Though not correct per say the bushings themselves will have to stay for now (machine shop difficult to work with in a timely manner).

#3 I am not to worked up about. I'm with you on the wider clearance for the intended, hopeful, potential RPM it will run next season

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As has been said numerous times here ... the way to fix your oil pressure issue is to address your oil hemorrhaging problem, which you don't seem to recognize as being of any importance.

I believe that oil pressure loss at higher RPM was your original concern.

And then: Think about this....huge over speed oil pump gets big gulp of aerated oil ,which leads to pump cavitation, which leads to jumpy/crappy oil pressure.

rmcomprandy wrote:As has been said numerous times here ... the way to fix your oil pressure issue is to address your oil hemorrhaging problem, which you don't seem to recognize as being of any importance.

I believe that oil pressure loss at higher RPM was your original concern.

I do indeed recognize the importance of the oil pressure issue and I understand that ideally I would be able to fix all of these. That is not affordable in both time and money right now. Not the right reasons I know, though it is the real reason.

I was in hopes for some insight into an option affordable enough for my current situation, that would help not necessarily fix my current situation, which I got and am extremely thankful for.

I very much appreciate the things that you gentlemen brought to attention as trouble areas. I do not disagree with any of it. I just can not tackle it all right now.

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Lem Evans wrote:And then: Think about this....huge over speed oil pump gets big gulp of aerated oil ,which leads to pump cavitation, which leads to jumpy/crappy oil pressure.

I would agree. This is something we will be able to play with once together

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EverySparePenny wrote:

I do indeed recognize the importance of the oil pressure issue and I understand that ideally I would be able to fix all of these. That is not affordable in both time and money right now. Not the right reasons I know, though it is the real reason.

Setting some oil clearances tighter and slowing down the pump shouldn't cost a whole lot.
As I said ... you don't seem to think that the oil hemorrhaging is important enough to alleviate some.

If that isn't even affordable then what is ...?

rmcomprandy wrote:

EverySparePenny wrote:

I do indeed recognize the importance of the oil pressure issue and I understand that ideally I would be able to fix all of these. That is not affordable in both time and money right now. Not the right reasons I know, though it is the real reason.

Setting some oil clearances tighter and slowing down the pump shouldn't cost a whole lot.
As I said ... you don't seem to think that the oil hemorrhaging is important enough to alleviate some.

If that isn't even affordable then what is ...?

Seems to me that this guy is trying to live on steak and caviar on a peanut butter and jelly budget, another thing is I think he is just here to get the right answer, or another words wants everyone to say his combo is great, he is right and maybe him and the one and only God of all Gods can stear him down the KBOOM path. don't see how he can afford to worry about drain back hole is this other stuff is just as cheap....


several problems exist here
to much clearance
to much oil ( oil to close to windage tray)
to much vacuum


Oh and a shout out up yous and a happy holidays

EverySparePenny wrote:

Lem Evans wrote:E.S.P. : Installing external oil drain backs has some up side and no down side. But, don't over look the obvious.

1] Pump pressure section is bigger than it needs to be. Pump drive ratio is higher than it should be, especially given the time the engine is at high RPM.  The thing is trying to pump too much oil and the "too much" oil is being offered an escape route....see #2.

2]  {A} The lifter bushings really do need to be replaced. The .041" hole in them is about twice the size they need to be if a guy was trying to restrict the oil.
    {B} """""""""""""""""""""""""""""""""""""""""""""""""""     .0035" lifter to bushing clearance is a huge leak. Like Scott said, ~.002" works.

3] I'm thinking you said the rod bearing clearance is .0035".....if so....it could be less but, given the 2-1/2" rod journal and the engines RPM range I'd rather see .003" than .0025" .

Thank you Lem

I will definitely be playing with #1.

#2 I might be able to partially tackling if I can find a tighter fitting set of lifters than the Comps. Though not correct per say the bushings themselves will have to stay for now (machine shop difficult to work with in a timely manner).

#3 I am not to worked up about. I'm with you on the wider clearance for the intended, hopeful, potential RPM it will run next season

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Lifter clearances here are probably your biggest oil loss. New bushings with smaller restrictions and tighter clearances will solve that. Call Claud @ CHE in CA or Precision Products Performance center in NC. Probably the most important and effective change you can make. Morel lifters are also typically a little larger in diameter than most, if new lifters are a possibility.

Scott, Lem, Doug, Randy, David, Bill, Boss, Thank you gentlemen for your insight and knowledge. As you all have pointed out I do have some oil delivery and clearance issues to attend to.

I appreciate all of your guys' input and will administer as much as I can to help curb the issue I am having.

Again thank you

At the risk of reputational ruin I'm going to have to disagree with Mr. Clark on one of his points. 12" of Hg is not too much vacuum for this engine.

When things are done right the spur gear style external pumps are a game changer.

Thank you Lem

In your opinion is there an amount that is "to much" vacuum? In a perfect world of course.....

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EverySparePenny wrote:Thank you Lem

In your opinion is there an amount that is "to much" vacuum? In a perfect world of course.....

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Not answering for Lem, but I'll agree with him and my answer would be no.

Thank you Scott

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EverySparePenny wrote:Thank you Lem

In your opinion is there an amount that is "to much" vacuum? In a perfect world of course.....

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There is no a perfect world that we live in.

Touche'

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