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PCV Air Oil Separator
https://slantsix.org/forum/viewtopic.php?t=53666		 Page 2 of 3
Author:  pishta [ Tue Oct 29, 2013 8:35 am ]
Post subject: 
The 2 90 ports (they are NOT turnable as I thought) on the top are the in/out port, just plumb the PCV hose to one side and the intake hose to the other. The 2 fittings included (clamped together) are solid plugs. No idea what they are for. The round bracket gets hose clamped to the body (little rubber stickers are for vibration?) and the flat bracket gets mounted to the firewall and then the screws bolt these together. The blue hose is just vacuum hose. When you get it, remove the top fittings and get some O-rings, as they use some sort of RTV gasket that MAY leak (might be fine out of the box) the 2 side fittings are doped and O ringed to the clear sight tube(can remove whithout taking hose off). The bottom is O ringed. Actually pretty good stuff for $20 shipped but its a little rough in the tapped holes. I had some tap flashing in the can, remove the bottom plug and look up in there and use a long screwdriver to knock flashing off tappings and clean out. Filter? I wouldnt use one as it would hinder the drain ability. The Filter should be on the breather anyway. Solids at velocity dont like to make turns so the oil goes straight to the bottom while the cleaner air happily makes the 90 and goes back into the intake.
Author:  Ssg Pohlman [ Tue Oct 29, 2013 1:13 pm ]
Post subject: 
Quote:
Quote:
$50! Try this: http://www.harborfreight.com/38-in-comp ... 68230.html
Dont do the harbour frieght, the drain valve is spring loaded and set to open. Only time it closes is when there is pressure in the lines. Ask me how I know :roll:
Author:  Aggressive Ted [ Tue Oct 29, 2013 2:33 pm ]
Post subject: 
Quote:
Filter? I wouldnt use one as it would hinder the drain ability.
The Jeg's version has a very nice filter that keeps 99.9% of the oil out of the intake and engine. The cheaper units do not have this high flow filter. I take mine out once every 6 months and clean it with soap and water.

The filter does in no way interfere the draining of oil. The oil drains out in a matter of seconds.
Author:  pishta [ Tue Oct 29, 2013 6:03 pm ]
Post subject: 
So maybe some sort of K&N style filter sock on the inlet pipe inside? Perhaps that way it wouldnt get down in the oil.
Author:  kxracer728 [ Tue Oct 29, 2013 7:23 pm ]
Post subject: 
Aggressive Ted,

Could you use something like this with one of the universal catch cans on ebay?

An inline oil/water separator on the outlet side of the catch can going to the carb. To catch any residual oil, debri before it gets to the carb...do you think this might restrict air flow to the carb?

http://www.harborfreight.com/oilwater-s ... 68246.html
Author:  Aggressive Ted [ Tue Oct 29, 2013 7:33 pm ]
Post subject: 
kxracer728,

Maybe......but it would sure fill up fast.....
You need a bigger container not smaller.

The You-Tube video of the new Cadillac engine with one is huge in comparison to mine. It is about the same size as the Moroso air oil separators.
Author:  kxracer728 [ Tue Oct 29, 2013 8:50 pm ]
Post subject: 
Quote:
The You-Tube video of the new Cadillac engine with one is huge in comparison to mine.
Do you have a link? I did some searches can't seem to find the video...
Author:  olafla [ Wed Oct 30, 2013 4:10 am ]
Post subject:  A catch tank design, and some notes on PCV valves
I made a thread last winter, asking about possible reasons for lots of foam on the dip stick, which I never have experienced before. I later found it to be a frozen PCV valve, causing the trapped water vapors to create foam in the engine oil. I am therefore making an oil/water vapor separating catch tank.
  • It is made from a cheap stainless steel drinking bottle of the type used by hikers or in sports, similar to the type shown below.
  • It will be mounted upside down, with a hole in the bottom to hold the stock PCV valve that normally sits on the valve cover.
  • The hole in the valve cover is fitted with a 90° open nipple instead of the PCV valve, and it has a hose to the catch tank intake pipe.
  • The stock hose from the PCV valve to the carb is used.
  • I was fortunate, in that the bottle neck has 3/4" pipe threads, so standard brass or steel pipe fittings can be used.
  • I have a reduction from 3/4" to a 90° 3/8" nipple for a hose.
  • The hose is made from clear, oil resistant plastic, and is used both as a level indicator, and to empty the contents of the tank.
  • The clear hose is pushed onto a 'blind' nipple, as shown on the illustration, when serving as a level indicator.
  • Inside the bottle, some coarse ss pot scrubs are held in place by roughly cut ss insect screen, of the type used in window or door openings.
  • If the screens are made oversized, and just roughly showed in, the friction against the sides of the bottle will hold them in place above and below the scrubs.
  • One or more scrubs should be pushed onto the pipe inside the bottle to prevent leakage of non-condensated gases along the pipe, the other scrubs stacked around them, depending on their size, of course.
  • Ordinary copper/brass/steel pipe parts can be screwed onto the bottle by making a flat spot with a hole in it, or you can glue, solder or braze them onto the stainless steel.
  • The shiny grill on a Rolls-Royce were actually made by soldering together stainless steel plates with ordinary plumber's solder and equipment!
  • The bottle should be mounted away from a heat source, the idea is that the vapors condensate inside the bottle, but be careful when placing it, so it don't freeze in winter.
  • The tank will be held in place by those nice, anodized aluminum clamps for turbo pipes. :D
    Well, no, probably not, they each cost more than the bottle and the other parts together, exhaust pipe clamps are more likely.... :cry:
Image ImageImage

Unfortunately, the 904 in my Aspen broke down, so I haven't been able to test the catch tank yet. Besides, I am at a different location, so I can't even produce a photo. I will publish one later. Here is the source of inspiration for my version of the catch tank.

If your engine is modified, you may need a different PCV valve, but which one?

The PCV valve is a necessary addition to the engine to reduce emissions. It is vital that it is working correctly for another, more practical reason, and that is to remove vapors and gases in the crankcase which will create acids that break down the engine oil. The PCV valve is created for a spesific engine's flow of air through the crankcase, and the calibration is a combination of restrictor hole size, spring pressure, pintle size and design. The movement of the pintle is caused by vacuum and air flow, against spring pressure. Because a PCV valve is regarded as a vital part of the emission equipment, it's calibration is not made public, as it is not to be altered.
Car manufacturers have taken the 'vacuum leak' caused by the PCV valve into consideration when they calibrated the carburetor or FI intake systems on a stock engine. An incorrect PCV valve may give unstable idle and low speed running problems, and also suck much oil.
When the PCV valve is in low-flow position, it may be fully closed, or may have a small opening, depending on application. The moving pintle inside the valve can be a ball or a cone.
  • Engine off = no vacuum = PCV valve closed by spring
  • Engine at idle = max vacuum = little blow-by = PCV valve in low-flow position
  • Accelerating from standstill = low vacuum at first= increasing blow-by = PCV valve closed at first while carb sucks fuel, but gradually opens as vacuum rises
  • Any cruising speed at medium to high rpms = medium to high vacuum = medium to good flow in PCV valve
  • WOT = vacuum drops to next to nothing = PCV flows max, but vacuum level is too low to make a difference = max blow-by = an eventual positive crankcase pressure may instead evacuate through the breather's hose back into the air filter box, and is the reason for oil-soaked air filters...
  • Sudden release of the gas pedal = high vacuum = PCV valve moves to low-flow position
  • Engine backfire causes the PCV valve to slam shut immediately
The PCV valve design is a compromise, there are too many variables to make it work as intended in all situations during an engine's lifetime. The fact that it doesn't even work when the blow-by is at it's greatest at WOT, is a real miss. A large connection to ported vacuum would maybe solve that problem, but create a lot of others.

Situations that may cause the engine behave strange at idle:
  • The incorrect PCV valve in used.
  • Big cams with low vacuum at idle can make a stock PCV valve behave different. At idle with a stock cam, there is high vacuum that put the pintle in PCV valve in the 'low flow' position. A big cam that produces low vacuum at idle, will put the pintle in the 'full flow' positon, having the effect of a vacuum leak that creates a lean and unstable idle.
  • If a modified - or unmaintained - engine, which makes just enough vacuum at normal idle speed to keep the pintle in a low-flow position, have a drop in idle speed when the transmission is put in gear, and thereby lower the vacuum enough for the pintle to move to 'full flow' position.

An incorrect PCV valve may be the reason for some of the problems with carburetor adjustment on a modified engine, reported by some members. Using a PCV valve made for a High Performance engine with low vacuum at idle, may be a solution.

This is a text copied from another forum, describing the calibration to a spesific engine.
D. Positive Crankcase Ventilation (PCV) Valve
1. Test Procedure and Criteria
a. Measure the flow of the PCV valve in standard cubic feet per
minute (SCFM) vs. pressure differential across the valve over a range of
operating pressures from 4-22 inches Hg., at standard atmospheric
conditions (21.1 [deg]C (70 [deg]F) at 755mm (29.92 inches).
b. A PCV valve shall flow within the vehicle manufacturer's
specifications or shall meet the following criteria: Whenever the mean
of the original equipment flow curve is below 1 SCFM, a maximum
deviation of the mean replacement PCV valve shall not exceed 0.1 SCFM.
Whenever the mean original equipment curve is
equal to or greater than 1 SCFM, a maximum deviation of the mean of the
replacement PCV valve shall not exceed 10%. The
total flow tolerance of the replacement valve shall not exceed the
original equipment variation from the mean, at any pressure
differential.
2. Durability Procedure: The flow of any specific PCV valve must not
deviate from the flow curve of the original equipment PCV valve by more
than the total original allowable tolerance when each is similarly
operated in the intended vehicle application over the service interval
stated by the certifier.

Olaf
Author:  Aggressive Ted [ Wed Oct 30, 2013 6:43 am ]
Post subject: 
Quote:
Do you have a link? I did some searches can't seem to find the video...
Sure, very easy to find...

http://www.youtube.com/watch?v=Y9klkDCItEY

Moroso TV: Moroso Air/Oil Separator / Catch Can test 2009 Cadillac CTS-V

There are many of them I just happened to like this one since you could see it in action.
Author:  kxracer728 [ Wed Oct 30, 2013 9:57 am ]
Post subject: 
Thanks...good example of how much oil is going back into the intake thru the PCV!

I could tell on my truck awhile back when i disconnected the pcv line from the carb. I was surprised at how much oil residue was coming out of the hose and wondered how that was affecting carb, idle, tuning!
Author:  robertob [ Wed Oct 30, 2013 10:32 am ]
Post subject: 
To add another data point to the PCV valve discussion:

- some engines (LS2 GM truck from 2002 on) have no valve at all, but a tiny restrictor.

Using a variable restrictor would enable you to tweak the flow until you get it to the exact right level. The downside would be a larger vacuum leak, but I bet you could adjust the carb to compensate.
Author:  Rug_Trucker [ Wed Oct 30, 2013 11:03 am ]
Post subject: 
:)
Author:  pishta [ Wed Oct 30, 2013 11:51 am ]
Post subject: 
Looks like a baby food jar! Hmm.......unscrew jar to drain..jb weld 2 stub outs into the cap or use bulkhead connectors, hose clamp cap to something...free!

Efi can get away with murder as the ecu accounts for intake vacuum levels and can alter iac or even open and close pcv orifice.
Author:  Aggressive Ted [ Wed Oct 30, 2013 12:39 pm ]
Post subject: 
Quote:
Using a variable restrictor would enable you to tweak the flow until you get it to the exact right level. The downside would be a larger vacuum leak, but I bet you could adjust the carb to compensate.
You can do that with the filter media.
Author:  Aggressive Ted [ Thu Oct 31, 2013 7:19 pm ]
Post subject: 
Nice work Olaf!

Thanks for sharing about the process of making your own and the filter media. Many of the eBay units do not have filters....which is a poor design.
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