Technical 327 pushing (dumping) oil out of breather, real head scratcher

Sorry I'm late to the party as I had a date today with the shoulder surgeon and I too am enjoying a little something something but it's from a little plastic bottle.
Tons of good input here so I really got only one thing to say about high volumn oil pumps and that they are known to pump way too much oil up to the top end of the engine.
My engine guy (RIP Mick) HIGHLY RECOMMENDED TO NOT USE THEM.
I replaced one on a 350 I built with a standard volumn pump, I had not even run the engine with the HV pump when the standard pump was recommended.
Funny thing found on @#$/& website that sells (not mfg) oil pumps.
"We are not responsible for collateral damage caused by the use of this product."

 

Oh, one more thing:
Hey Kerry, that last engine photo is my 327/350 hp engine for my 67 Nova.
But you knew that!

 

Pressure is pressure and Volume is volume [people confuse the two]

When the clearances are loose you use a high volume pump to maintain oil pressure at idle speeds [after that ,it is bypassing anyway]
When the clearances are tight you use a high pressure pump to maintain oil volume

Too much oil pressure or volume does not cause blowby , an oil pump bypasses internally

I didn't know that engine was yours but now google images have now made you famous [it's a nice example]

Unless the PCV hose and valve is blocked on the OP's engine, I think he might have to take squirrel's advice

 

You'll only end up with an oil slick under your car if you take a backward step and install a draft tube.

You need to check to see if the PCV hose isn't blocked [including the tomato can]
Also make sure you have the correct PCV valve, The ones that go in the Block, Valve covers, or Oil fill tube flow the opposite direction to the PCV that goes on the back of the Carb.

The PCV is a controlled vacuum leak, with a check valve for backfire protection

 

Is this a new issue or has it gotten worse over time? I agree with it needing rings, you have some blow-by going past them. I had an old truck with a shot engine, even with it being tired as hell it still pushed a lot of oil out the oil fill/breather. Do address the cylinder wall wash-down, you have to find a happy medium with the carbs and their set up. It may be worth investing in a little dyno time to help sort it out.

 

I hate chrome rings . Not one good thing I can say about them.

 

The last time I encountered an engine that blew oil out of the breather, it was an Olds 394 that had been repeatedly overheated. When pulled apart all of the rings were bad.

 

I’m wondering if the engine wasn’t broken in probably and the rings never seated.


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You need a set of Total Seal or Zero Gap rings.

 

Have you pulled the PCV out and put a finger over the end to see if there is vacuum. Also remember that most generic PCV's are designed to operate at a much higher vacuum than you are pulling.

 

why?

 

Eliminated all blowby in our racing engines Jim. Also leak down has always been under 1% after a season on the 1/2 mile and we are not ez on anything. They work for us......

 

X-cpe touched on it so let's finish this thought. At 7-8" you don't have a functioning PCV system. Add to that that 3/8" hose doesn't flow squat, I'm surprised you aren't blowing out crank seals yet. You're turning race rpm but have a marginal (even for mild street) breathing system. Function first, looks after.....

 

This is interesting... it makes me wonder why they would even make an HV pump. Back then, it was pretty much forced down my throat to get the HV pump. I just assumed that when you're gettin into a performance build, you wanted as much lubrication as you can.

The tomato can is a fresh install. As are the hose and pcv.

So, we may have something here. The PCV that I have is the standard run of the mill autoparts store special as per a vette website seen here in post #5
https://www.corvetteforum.com/forums/c1-and-c2-corvettes/3563940-road-draft-tube-to-pcv.html

Do you think that this may be causing some sort of block leaving the crankcase pressure no other option but to route up to the fill spout?

It has always pushed oil out of the breathers (used to have the aluminum style with holes) they didn't have any baffles in them so I just chalked up oil being in the breathers to that. I do remember that when I didn't have the scruntchie trick under the breathers, there would be oil all over the firewall, more so on the driver than the passenger.

I've been fiddling with the carbs for some time now and finally found a sweet spot. This thing is responsive as hell! Running better than it ever has. One peculiar thing that I am observing is that I am getting continued fouled plugs on the drivers side bank and lean on the passenger? Really driving me nuts.... but like I said, running hard! I originally thought that I had an extreme case of blow by on that bank of cylinders but, ironically the test showed that those cylinders had less leakage than the passesnger side!

Wouldn't a leakdown test confirm this?

Break in consisted of 15-20 mins holding 2-2500 rpm. I was told that this was necessary for the solid tapper cam break in?

No, haven't dont that test yet. I assumed it was working because all of the parts were new (with the exception of the tomato can, that's an original piece that has been throughly cleaned).

I feared the low hg issue with my cam and the pcv. However, when I checked the vacuum it's steady at 7-8 at idle... obviously dips when initially revved then back up to 20 hg or so. I assumed that this would be enough, especially at high rpm?

I'm curious on this one too...

 

What would your suggestion be? I do have the old covers with the holes. Could always throw them back on.

To be frank, I just want to have fun with it for the next few months, so any sort of band aid fix will do. Throwing the valve covers with holes back on really defeats the purspose as it still pushes oil out. I moved to the no holes because the oil from the breathers were Jackin up my headers and I was afraid the oil blowin onto a hot header would catch flame. My front clip is fiberglass so the car would be a goner if that were to happen.

After tax season I was anticipating on pulling the engine out and straight axling it. Been talking about doin it for nearly 20 years, it's time. I can do a quick rebuild on the engine while I have it apart. That's not a big deal.

 

Just my opinion fellas, When you install a high volume/high pressure pump it creates a lot of havoc in the engine. All that oil has to go somewhere.It is pushing past the lifters and dumping on the top of the spinning crank. It is being pushed out the side gap on the rods and adds to the turmoil around the crank .It is just a lot of extra oil flying around. The crankshaft spinning throws a lot of oil on the cyl walls making the oil rings work too hard and maybe can't even keep up with the volume. Your amount of ring leakage is too high and the oil rings may be floating on the excess oil..You will never get it to seal up that high. And from my experience ,we would never consider using an engine with that kind of leakdown,we thought 8 or 9 percent was rebuild time. best of luck.

 

What about a scavenge tube in the headers? An evacuation tube, used to create a venturi to help relieve some crankcase pressure.

 

You could make/buy a catch can. As a temp. fix. No breathers on engine, run breather hoses to container with a breather on top and drain valve on bottom.

 

Some time ago I was thinking the same thing about the HV pump. But, dismissed it as they are commonly installed and I have yet to hear any complaints. But, you know how some guys get with their engine builds. Don't like to talk about the negatives, just how hard it runs LOL.

As far as the leakdown test, I thought that was high. As soon as I hooked the air up, the hissing through the crankcase was apparent. However, according to the gauge it is within "acceptable" range (green). I want to say after 30% it goes to "moderate" (yellow) and so on. I have a couple cylinders that had 10% and that registered on the gauge in the "set" area. I really have no reference to go off of. I can only assume that the %'s provided on the gauge are applicable in my situation.

Maybe I'll just stuff a cut square of a microfiber rag under the breather cap and call it a day until tear down, which sounds like is the solution to my problem.

 

I considered that cause my pops swears by it but, I'd really hate to cut up my fenderwells to band aid the problem. And if it didn't work, I'd be pissed that I cut up my headers and didn't get a thing outta it but lost time. Ha ha ha!

This would require putting the old "hole" valve covers back on?

 

The only thing I would be concerned with, is possibly using this setup with mufflers. They are primarily designed for open headers.

 

25% may be acceptable but not a 8000 rpm possible helps roller rockers, most limit the oil to the top end somewhat. Chrome rings are fine if the right break in is used. 180 grit hone set timing valve lash before starting, fire engine check for leaks and drive do 10 reps 50 to 70 in high gear then do final adjustments. All rings need a load to seat. This procedure was from perfect circle I've used it for 50 years it works.

 

At this point I'm not sure that you will come to any conclusion as to the overall oil issues
UNTIL BOLTS GET REMOVED!
It's time to stop typing and start wrenching, plenty of useful input here so far.
As to the spark plug fouling issue; when did this start, is it all on one head, is it fuel fouled or oil fouled?
When there is a combination of too much oil up top and worn valve stems, guides and/or seals you will have an on-going oil fouled spark plug issue.
I bought a pair of "freshly rebuilt" LT-1 heads many years ago for a 350 rebuild, the valve stem to guide clearance was not "freshly" addressed, in less than 800 miles I put two full sets of plugs in it due to oil fouling, decided to just put new Edelbrock aluminum heads on.
A handful of other upgrades and health issues have kep me from getting it going but it should be quite a nice street engine.

 

Take the drain valve out of the bottom, and replace it with a check valve & a hose back to the crankcase.
And mount it higher than the engine.
When there is no crankcase pressure the check valve opens and allows drain back.

 

Don't want to hijack this thread. but while we are on the subject of leakdown tests, what is an acceptable figure for a hot street, occasionally raced 6500 rpm sbc? I have hypereutectic pistons so my ring gaps are about 50% wider than forged pistons per Keith Black piston instructions.
Also I have a high volume oil pump because I have the Comp Cam lifters with a .012" hole in the face of each solid lifter for additional cam lobe oiling. These 16 .012 holes bleed off quite a bit of oil and the Comp Cam tech told me that a HV oil pump was a good idea with these lifters. I also have Comp Cam moly steel roller rockers.

 

YES! This is correct. I've posted this same thing several times, but first time I've seen it from someone else. This is a basic truth of all pressure lubricated and hydraulic systems. Pumps only create flow, not pressure. Resistance to that flow results in pressure.

Yeah, I agree with your engine guy. The biggest issue is the shearing of the oil that leads to heating & oxidation of the oil and shearing of the polymers used to improve viscosity index resulting in a loss of viscosity. And there is no advantage to the higher pressures created.

This it true too! If there is a blow-by problem, and it sure seems like there is, it's not because of a high volume pump, it's because of wear of the piston rings and cylinder walls. Could be piston deposits causing the rings to stick, polished bores, etc.

We've learned a lot over the past couple of decades. Though some people are slow to change and let go of old ways. Consider that as long as there is ANY pressure in the system, then there is sufficient oil in the clearances to provide needed lubrication. Higher pressures in the passages does not equate to increased lubrication of the mating surfaces, it just ensures adequate reserve supply of oil, which IS important. But at some point the only thing you're accomplishing is shearing and heating of the oil, and wasting horsepower pumping oil that cannot be used by the engine and is forced over the relief valve back to the pan. Better to use that horsepower to push the car than pump oil.

 

Two big horse power robbers to much oil pump and to much valve spring pressure.

 

The only oil getting "slung" around the crankcase is from loose clearances. A HV pump is needed to maintain pressure at low engine speeds. Above that ,all the excess volume bypasses internally in the pump.
Crank case pressure is not caused by windage. Crank case pressure is more air entering the crankcase than is leaving. This is caused by leakage past the rings on compression stroke [no rings seal 100%]

Think about this...... on a multiple cylinder engine [except triumph 2 cyl] pistons going up the bore are counteracted by other pistons going down the bore so the swept volume in the crankcase remains the same. The pressure is caused by leakage past the rings on compression stroke.
At high RPM you could be getting ring flutter in the piston grooves.

Pull the hose off the crankcase, you should be able to blow through the PCV into the carb.

I posted a couple of photos earlier.
On that engine of DDDenny's the PCV draws vacuum from the hosetail end.
on the PCV that bolts to the carb base it draws vacuum from the threaded end
those 2 examples flow opposite each other.

At 8000RPM at wide open throttle, there is no vacuum. So it is crankcase pressure that is evacuating out of every orifice available.

 

A couple of things, big cam hard on valve guides and I put rings in my street/strip motors @ 200 pass's, strip only 400 or less.
Pull it apart and give it a refresh it might just save your motor. Your running on barrowed time.

 

The acceptable number is 25% but that is the max doesn’t mean it’s still good, it’s like saying your propane bottle is 99% empty so doesn’t need to be refilled. At 25% leakage I would say it’s time for a refresh.


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