Head scratcher

[L31MaxExpress]

I agree with most of the points made above as well. I do run a high-volume pump; however, the upper end oil flow is limited by the size of the orifice in the lifter it is fed through and the clearance of the plunger to lifter body. I have had the engine at 2,000+ rpm with the covers off and there was very little oil splash. I could see the rockers acting like the paddles on a paddle wheel steamer, throwing oil mist like crazy. One other consideration is also the thinner viscosity of synthetic oil we use now vs when those first 265/283s came out and ran a straight viscosity of oil. I suspect something like an old 30 weight would be easier to keep inside the crankcase and less susceptible to airflow pulling it out of the crankcase. The early engines also had a HUGE canister style separator in the lifter valley that was tied to the road draft tube. The ones I have seen looked like a tin can that would have Dole brand Pineapple rings in it. Back to this setup having more vacuum, I definitely plan to throw a stock PCV valve back on this after let's call it a 1,000-mile PCV oil consumption test with the LS style fixed orifice. The stock valve closes to the smallest opening at higher vacuum and may actually decrease the flow at normal cruising speeds and loads and pull less oil.

 

[L31MaxExpress]

This is the old road draft style baffle. The fresh air vent on this style setup was high up on the oil filler tube pressed into the front of the intake manifold.

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[Road Trip]

I definitely plan to throw a stock PCV valve back on this after let's call it a 1,000-mile PCV oil consumption test with the LS style fixed orifice. The stock valve closes to the smallest opening at higher vacuum and may actually decrease the flow at normal cruising speeds and loads and pull less oil.

This thread is a great read/look over your shoulder. I really enjoy the ongoing analysis of internal oil control with the goal of optimizing
your powerplant's oil consumption vs the more often seen "It is what it is / If you're gonna play you gotta pay / I can't be bothered"
school of thought.

This thread reminds me of all the hubbub back in the day that surrounded the excessive oil consumption of the LS1 & LS6
engines that a small but vocal minority of Corvette owners were experiencing. Eventually the GM powertrain engineers figured
out what was going on, and based on their understanding were able to come up with a genuine fix for the owners with driving
habits that stimulated the problem:
(John Juriga on the 4 forces of ring flutter: Combustion pressure, Ring inertia, Ring's radial expansion pressure, Crankcase Pressure)

So the near-term warranty fix was the revised ring package for the small pool of drivers that could stimulate the excess oil consumption.

IIRC, the long term fix was some kind of internal block windowing that the engineers added in order to reduce
the 4th variable -- crankcase pressure pulsations. (And no, I'm not confusing this with the controversial Olds 403
block windowing.) Unfortunately, I can't seem to dig up the article describing the long term fix?

****

Given all of the above, I don't think that a discussion about oil consumption, catch cans, and ring flutter is an over the
top geekfest when thinking about what's going on inside a hard-working wet-sump V8. Like what L31MaxExpress is
debugging/documenting for our viewing pleasure. It's leading-edge effort like this that allows you to not have to
apologize for still enjoying a 1st-gen SBC in a sharp state of tune.

 

[L31MaxExpress]

I am also waiting to see what supercharged finds on his 1500 when he pulls the plugs out of it. He has boost on his with his Whipple but I am not sure that he uses that port for the PCV valve as that would be under boost.

I have honestly considered going back to a header evac setup on this again. They actually work very well even with a catalytic converter, just have to run a seperator setup to keep the oil out of them. I am sure this 383 would love some crankcase vacuum. Even the worn out old stock 305 that the Engine Power guys tested saw minor gains in torque with the header evac hooked up.

 

[KansasOBS]

Quite a bit of oil there.

Probably not wrong about the oil we have nowadays having some effect.

It isn't even just these engines. Over the years of working in shops I lost count of how many newer nicely taken care of, lower mileage vehicles had an intake full of oil. Ive pulled them off to carry over to the bench, and had it draining across the floor. Felt like just heading to the garbage can instead.

Yeah, header evac would be optimal. Windage tray if there isn't one wouldn't hurt either.

 

[L31MaxExpress]

Quite a bit of oil there.

Probably not wrong about the oil we have nowadays having some effect.

It isn't even just these engines. Over the years of working in shops I lost count of how many newer nicely taken care of, lower mileage vehicles had an intake full of oil. Ive pulled them off to carry over to the bench, and had it draining across the floor. Felt like just heading to the garbage can instead.

Yeah, header evac would be optimal. Windage tray if there isn't one wouldn't hurt either.

I have the long 3/4 length Milodon tray the longest I can run with the 5qt pan in both the 383 and the 350. They both have the Moroso rear main cap mounted oil pump baffle that doubles as a gasket for the oil pump being a softer metal than the cast iron. The windage tray extends well past the oil pan sump area.

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[Pinger]

First off, excellent detective work pinpointing the oil to cyl#4 issue - impressive.
A couple of points the relevance of I'll leave you to decide.

My suspicion is that Vortecs do have more blow-by than we might first imagine and, as per a comment made by Schurkey, the closer to WOT, the greater the tendency to blow outwards on the passenger side. Normally this is then consumed via the inlet tract from the entry point just downstream from the MAF sensor until such times as the crankcase pressure subsides. The reason I suspect this is that on the passenger side of mine I have disconnected the connection to the inlet (as described above) and instead have a filter on the end of the tube free to breathe to atmosphere. There is always signs of oil misting around it that can (as far as I'm aware) only be from that filter breathing back out of the crankcase. This on an engine that has a mere 50,000 miles on it and oil consumption that is roughly never worse than 4500 miles/qrt. My driving/usage is in hilly terrain where I probably spend enough time on-throttle to create the conditions of highish pressure in both crankcase and manifold which would encourage reverse flow out the passenger side pipe.

Re standard GM driver side pipe. I think, the restricted flow only comes into play at severe manifold depression eg, closed throttle over-run condition - not in milder on-throttle driving where the manifold pressure is below atmospheric but not so low as with closed throttle over-run. I could be wrong, but I think that's how it is configured.

 

[Supercharged111]

I am also waiting to see what supercharged finds on his 1500 when he pulls the plugs out of it. He has boost on his with his Whipple but I am not sure that he uses that port for the PCV valve as that would be under boost.

I don't think I ought to mess with it, it's installed as factory. With the bypass valve in place the engine still regularly sees vacuum. I did drill and tap a fitting for the charcoal canister between the blower and throttle body though as I'm not 100% sure how smart the logic is for that. Blower has to come off to do plugs and wires and I have bigger fish to fry at the moment, but I can't wait too long or weather will get me.

 

[Schurkey]

I ordered an oil seperating catch can that looks nice. It has an actual seperator in it and can be disassembled for cleaning opposed to some that are just a canister with two lines on it and a drain.

A decade ago--or more--guys went to any place that sold air compressors--the big-box home improvement store (Lowe's, Home Despot, etc.) and bought a cheap "Compressed Air Coalescing Filter".

(These are the EXPENSIVE coalescing filters.)
www.atlascopco.com/content/dam/atlas-copco/compressor-technique/industrial-air/documents/leaflets/air-dryers/compressed-air-filters/filters-2021/Filters_EN.pdf

But as soon as enough folks were putting air-compressor filter assemblies on their cars' PCV systems, the offshore "anodized billet" models got popular.

for 40+ years after using one of these daily for
a couple of years I miss having such an unfair troubleshooting advantage at my fingertips...

...When they were new the price of admission was such that only a pro mechanic doing this for a living could
justify the investment. But as an apprentice I felt so lucky to be using a Sun 1115 on a daily basis.

Yup. I worked with various Sun 'scopes, including the 2001 (briefly), and what I remember as the 1010 or 1015. Spent most of my time working with Allen 'scopes. No idea what the model number was.

My Snappy Counselor II is my favorite automotive 'scope, but they're ancient. They were well-built, but everything gets a little goofy with age. They were ~$10K in the 1990s when they were new, and when I bought mine I paid about $1K and got more accessories and the roll-cart.

I don't know what they go for now. Chump-change is my guess, but shipping will be expensive.

On the 383 we’re building my son I just bought some Total Seal gas ported rings, they are supposed to really cut down on blow-by, we’ll see.

I've seen promo pictures and description for those. The way I remember it, they're really expensive.

I'm tempted to cut grooves into the upper part of the piston ring land, to accomplish the same thing, but not require the spendy piston rings at every tear-down.

I think why catch cans are becoming more popular has something to do with us increasing the piston displacement while at the same time being forced to do this in the same total internal volume defined by the block...

...there's going to be a lot more 'slinky-style air movement' between cylinders that are 180° apart from each other
in terms of crankshaft rotation.

I had not considered that. THANKS.

more intense pressure pulsing on the same size crankcase on one side of the PCV valve, while at the same time more
intake manifold vacuum on the other side of the same valve?

A crying shame that the folks who MAKE PCV valves, don't provide any "user guide" to their differences in spring tension, flow rates, etc.

the first thing that comes to mind is to double-check the piston ring seal.

ABSOLUTELY.

This thread reminds me of all the hubbub back in the day that surrounded the excessive oil consumption of the LS1 & LS6
engines... ...the long term fix was some kind of internal block windowing that the engineers added in order to reduce
the 4th variable -- crankcase pressure pulsations... ...Unfortunately, I can't seem to dig up the article describing the long term fix?

I remember that. They made a big deal out of "bay to bay venting" I think they called it. Each of the "V Twin" bays--1 and 2, 3 and 4, 5 and 6, 7 and 8 which were separated from each other by the main cap webbing--could vent to it's neighbors more readily.

 

[SNCTMPL]

I've seen promo pictures and description for those. The way I remember it, they're really expensive.

I'm tempted to cut grooves into the upper part of the piston ring land, to accomplish the same thing, but not require the spendy piston rings at every tear-down.

The price has come down on them. I paid $200 for Summit brand, made by Total Seal.