HV oil pump/too much oil on top Q

[Belgian1979]

What about using restrictor type pushrods? I would rather not reduce oil to my lifters (roller lifters) as the car is run on the street.

I agree, read on here people using rollpins for pushrod restrictors. Still I'd prefer to improve drainback before restricting.

Boot, what do you suggest for improving drainback?

[dannobee]

On a SBC, about all you can do for drainback (from the heads) is clean up the cast iron on the ends, make sure the drainback holes are clear, and make sure that the head gasket holes are lined up and big enough to match the size of the drainback holes.

[ClassAct]

I’m not so sure that the HV oil pump is the issue. The pump can only force X amount of oil through the system, which is determined by the total amount of leaks. The HV pump can only get the bypass to open sooner. The total flow through the engine is the same. In other words the HV pump gets more oil to the system sooner and then the bypass opens. It can’t push more oil through the system, it can only produce whatever the X number is sooner.

[BOOT]

Boot, what do you suggest for improving drainback?

Like mentioned clean up oil drains, I'd also improve crankcase venting. A dry sump would be nice but external drain lines could also be added at the rear of the heads.

edit: Never done the drain lines myself but seen them.

[Belgian1979]

I don't remember any obstructions in the head return hole, but I left it untouched.
Yes, external lines, but it's quite elaborate and a 79 vette hasn't got place to spare in the engine bay as it is, especially on the drivers side.

[fabr]

Have you done a leak down test on the engine? Excess blowby even on a fresh engine is many times on a SBC the culprit to inadequate oil return to sump . The blowby has to go somewhere and that is usually a breather mounted on one or both of the valve covers to vent to atmosphere. That blowby seeking a path to vent blows the oil back into the heads and hinders oil return to sump. As said in an earlier post there are not a lot of return paths and the blowby can easily block/hinder the return to sump.

[Belgian1979]

Have you done a leak down test on the engine? Excess blowby even on a fresh engine is many times on a SBC the culprit to inadequate oil return to sump . The blowby has to go somewhere and that is usually a breather mounted on one or both of the valve covers to vent to atmosphere. That blowby seeking a path to vent blows the oil back into the heads and hinders oil return to sump. As said in an earlier post there are not a lot of return paths and the blowby can easily block/hinder the return to sump.

See one of my previous posts with a youtube movie. I measured the amount of blow-by coming from the valve cover with a flow meter that I also use to set the gas flow on a welder. It resulted in 0.5 cfm (13 l/min). I don't have a leakdown tester. Compared it to my dd (2.0 tdi at idle) and that one has more blowby then the vette.

I did a compression test and al cylinders are around 183-185 psi.

[fabr]

Have you done a leak down test on the engine? Excess blowby even on a fresh engine is many times on a SBC the culprit to inadequate oil return to sump . The blowby has to go somewhere and that is usually a breather mounted on one or both of the valve covers to vent to atmosphere. That blowby seeking a path to vent blows the oil back into the heads and hinders oil return to sump. As said in an earlier post there are not a lot of return paths and the blowby can easily block/hinder the return to sump.

See one of my previous posts with a youtube movie. I measured the amount of blow-by coming from the valve cover with a flow meter that I also use to set the gas flow on a welder. It resulted in 0.5 cfm (13 l/min). I don't have a leakdown tester. Compared it to my dd (2.0 tdi at idle) and that one has more blowby then the vette.

I have reservations using a welding gas flowmeter to gauge how much blowby you are experiencing. I can address that if you wish in a later post.

For the moment though we will accept that it is correct. If it is correct there are very few things that will allow flooding of the rocker covers other than blocked/hindered drainback. I think I remember you are using T&d shaft rockers so for the moment we will assume they are not involved. That only leaves the pushrods really to transfer the flooding oil. Are they new? Are the holes oversize from normal due to wear? Were they possibly from a source that might not have controlled the pushrod ends holes? The hole size in a pushrod end is the metering orifice to the topside as is the hole in the lifter pushrod seat and/or the rocker adjuster cup. I can think of nothing other that could increase the flow of oil to the topside and even then I would have to believe that drainback is the issue.

[Belgian1979]

The pushrods are new units, bought after installing the rockers as I needed a custom length. Standard diameter. Didn't ask for a special opening in them, so I assume they are standard.

Why is a gas flow meter not good? Just to make sure this is clear, I plugged the PCV, put a tube that closed up the breather on the other side and put the hose in the rubber of the gas flow meter. I assume these do give a good indication.

[fabr]

THe problem with trying to use a welding gas flowmeter is that they are calibrated to a much higher pressure than the crankcase will see. Therefore the flowmeter will give very inaccurate results.There are flowmeters calibrated to much lower pressures with much larger passages for automotive/diesel usage. The welding gas flowmeters have very small orfices for much higher pressure that just will not flow the flow that will be seen from blowby at much lower pressure. This is much like the oil pressure thing. Loose tolerances will flow much higher volume at low pressure than tight tolerances willl at higher pressure. Blowby is a fluid just like oil so the basic laws of fluid flow apply to both.Sorry if I said that about as clear as mud . I'm on the road now and not enough time to say it better.

On another note.are you sure your flow meters are showing cfm and not cfh? All my welding gas regulators are in cfh. The reason I ask is I just cannot believe your engine has only .5cfh blowby if they are actually in cfh instead of cfm. Even if correct they read in cfm , .5cfm is a really tight engine. This is why I am skeptical of the readings you are getting with a welding gas flowmeter.

[BLSTIC]

What would happen if you use a thinner oil? Wouldn't it flow back down faster? If you have a high volume pump you almost certainly could keep the pressure up.

[Belgian1979]

THe problem with trying to use a welding gas flowmeter is that they are calibrated to a much higher pressure than the crankcase will see. Therefore the flowmeter will give very inaccurate results.There are flowmeters calibrated to much lower pressures with much larger passages for automotive/diesel usage. The welding gas flowmeters have very small orfices for much higher pressure that just will not flow the flow that will be seen from blowby at much lower pressure. This is much like the oil pressure thing. Loose tolerances will flow much higher volume at low pressure than tight tolerances willl at higher pressure. Blowby is a fluid just like oil so the basic laws of fluid flow apply to both.Sorry if I said that about as clear as mud . I'm on the road now and not enough time to say it better.

On another note.are you sure your flow meters are showing cfm and not cfh? All my welding gas regulators are in cfh. The reason I ask is I just cannot believe your engine has only .5cfh blowby if they are actually in cfh instead of cfm. Even if correct they read in cfm , .5cfm is a really tight engine. This is why I am skeptical of the readings you are getting with a welding gas flowmeter.

I don't agree.

This is a gas so the gas low applies. P1 * V1 = P2 * V2 = constant. P2 pressure is always atmospheric, so no matter what the initial pressure would be the V2 would adapt itself to make sure that P2*V2=constant. So these measure the flow exactly as they should imo.

It is rated at l/h but you can recalculate that to cfm. The measurement was 13 l/h.

One thing that I found strange though is that the ball was going up and down. The 13 l/h is the high point. So the flow of blow-by is not constant. I would think one hole would be bad, but that's not the case as all the compression readings are the same and all plugs are equally oily.

[Belgian1979]

What would happen if you use a thinner oil? Wouldn't it flow back down faster? If you have a high volume pump you almost certainly could keep the pressure up.

I use 5W40. I would think that going down too much in viscosity carries its own risks.

[fabr]

You are more than welcome to disagree . I would continue discussing/debating/explaining but that is frowned upon.The facts have been laid out as to the very few causes of your issue. You don't understand and I'm good with that. Best wishes and Happy New Year!

[RDY4WAR]

What would happen if you use a thinner oil? Wouldn't it flow back down faster? If you have a high volume pump you almost certainly could keep the pressure up.

I use 5W40. I would think that going down too much in viscosity carries its own risks.

Correct, but it depends on the engine. There's a lot of people running 15W-40 and 20W-50 in an engine that realistically could go 500k miles on a 5W-20. Too high of viscosity carries its own risks as well. Note that I'm not saying your choice of 5W-40 is wrong, I don't know your engine, just putting that out there.

If the oil is leaking past the valve seals, they are typically elastomer rubber. You could try an oil with a decent bit of ester or naphthalene. Though it's usually added to higher end oils for thermal and shear stability and solubility, they also happen to work quite well at conditioning seals. I know of a couple good oils that fit that ticket off the top of my head (HPL Premium 5W-40, Red Line HP 5W-40), but that's here in the US. I know the HPL isn't available in Belgium, not sure about Red Line. Motul 300V Power 5W-40 would work.