PCV with open or closed crankcase?
 

I have a 427 FE with 2x4 tunnel wedge intake manifold. I see a need for a change in my crankcase ventilation system. I currently have the usual baffeled oil filler tube in the right front of the intake manifold with the usual push on breather, and a cast alluminum breather stack at rear center of the intake manifold. The 2 valve covers are the cast alluminum Lemans valve covers. Each valve cover has a grommet that converts the twist in hole to a small hole for a PCV valve. There is a 90° PCV valve in each valve cover. I have purchased a chrome Motorcraft EC-2 breather cap which I had planned on replacing the grommet and valve in the rear of the right valve cover and routeing the flow through a 3/8 hose to a fitting on the other side of the intake plenum that would have manifold vacuum. The engine sits pretty much level so the intake tilts the carbs lower infront. There is not much more height clearence on the front of the left valve cover. I was just told by someone that I need to do away with the most of the breathers so as to actually pull a vacuum on the crankcase. I was preparing to remove the grommet and PCV valve in the forward portion of the left valve cover and replace it with a twist in breather cap ,but may now change the PCV valve with an 3/8" elbow. Please, I need some more input . What did you do ? what worked for you?

As I understand it, the PCV system needs a filtered source of air (air cleaner housing, filtered breather, etc.), but I don't think you could have too much...it would be like a vacuum secondary, only the air flow that's is needed gets used. Also, if you have more blowby than the PCV can suck out at WOT, the breathers will let it vent without building up pressure in the crank case. I would recommend having the breather on one valve cover and the PCV valve on the other for a sort of flow-thru system (in one side, out the other).

PCV valves are an anti-polution device, not a crankcase negative pressure machine. You will not build up pressure in a crankcase that does not have a PCV valve attached to it. Who started this rumor anyway? Engines ran for decades without PCVs with no problems. Go to your local racetrack and see how many engines have a PCV valve attached, I know the answer already.

If you want, run with a breather on both valve covers. Having the PCV valve won't hurt anything, but don't think it's adding HP.

Bob

Before PCV was a blowby tube. The PCV was the earliest form of a smog device.The blowby tube allowed blowby gasses from the engine to vent into the atomosphere. The PCV allowed the engine vacuum to pull blowby gasses from the crankcase into the intake manifold and burn them in the cylinders.The breather on the valve cover allows fresh air to be drawn into the crankcase as the blowby gasses are drawn thru the PCV to the cylinders.If you don't have a breather on the valve cover the system will not work, and pressure will build up in the crankcase and the pressure has to go somewhere. The weakest pace in your sealing system will let go. OIL leaks big time. Simple solution is vented breather on valve cover and a clean PCV to remove blowby gasses. By the way the PCV opens to remove the blowby gasses and closes to keep the oil in. It only works off the intake manifold vacuum. Hope this helps.

One thing at this point now the PCV valves only flow when the carbs are passing air. When I had an incident the mess was mostly on top of the primary carburetor. The foam S&H air filter element was oily and there was that mess all over the carburetor and its airbleeds.
Went on a four hundered mile trek. Left home Saturday morning with everything topped . Sunday morning ( in a slanted parking spot at the motel ) I checked the oil level. The dipstick showed only gray foam. The foam was even up in the dipstick tube. I hiked down the street and bought 5 quarts of Mobil 1 20ww50 full synthetic oil. That filled it up again. On the trip up on Saturday,water temp was what the thermostat was set for 180°. The oil temp at the pan was running 210° to220°. Sunday comming home it was a little warmer outside and we got stuck in a virtual parade. Water temp was running 190° and oil temp was also running 190°. Spark plugs were fouled, the engine (when slowed down to idle )wanted to die at the original idle setting. Later Sunday at home and now the oil level was and is fine and all the gray oily foam is gone.

Are most PCV valves the same? Do I just lookfor one that has the plumbing to make it fit my setup?

Mike - I was wondering the same and everything I saw seemed to indicate the valve is generic ie there are not different types, at least for Ford FEs. I think as a starting point you should consider having one "exit" point from the crankcase and that's where the PCV valve goes. Then determine where your one "entry" point is going to be for fresh air and put a breather there. Likely you'll have the PCV on one valve cover and the entry point will be a breather on the other valve cover. Close the rear intake breather port with a piece of gasket material, and plate, or if you like the look, just put the solid gasket under the breather stack so it shuts off the air flow. Close off any other entry points ie the extra openings on the valve covers. I think ideally you want the entry point and exit points to be as far away from each other as possible to best ventilate the entire crankcase.

Hook your PCV to the vacum source under the carb, or on the intake port - however, if the intake port you are using is in one of the runners, you could be negatively affecting that one cylinder's performance. That's why most connect at the carb base.

Run it like this and see if you're still getting blow by - likely out the entry point breather cap. If so, you may want to consider why you're getting this much blow by - remember, the blow by is lost compression going past your rings. Also check your PCV valve and make sure it's working and that there is a vacum pulling on the line connected to it so that's it is indeed pulling vapor out of the crank case.

I assume you're getting all the oil goo on your carb and filter because there's a line running there that serves as the fresh air source for your "entry" point. The blow by is exceeding the ability of the current system to vent it, so it's backing up out this entry line.

Hope this helps - I've just finished fighting through the same thing.

One other thought on your grey foam - do you have a windage tray in your oil pan, and you're not over-filling the oil? If not, the crank could be churning up your oil. You are likely also getting blow by going up the oil dipstick tube as well and that's creating foam also. Just make sure the foam is not from water as well - a much bigger issue with which I am all too familiar.

Also, you can create an oil filler tube cap with a PCV valve built in to it by using a breather cap with PCV and putting the rubber grommet into the end of the fill tube and then inserting the breather cap. I did this on my old intake, but found I had to use a radiator hose clamp to keep the breather cap from coming loose from the oil filler tube. Kept me from cutting holes in my valve covers - which I have since had to do since the Edelbrock intake doesn't have an oil filler tube.

HSSS427 is right all of the PCVs are the same because they all do the same thing. Some may be larger in dia., but are the same.Tell the parts guy what you want it for, and he should get the one to fit.My PCV goes the in at the base of the carb.If you have excessive blowby you may have a mechanial problem.ie bad rings?
Good luck sharpe 1

Question to All...
 

So do all 427 so have blow by or just ones that have worn rings or cylinders?

My next move on my 427 was to take it to someone who will just set it up with a puke tank. I put 2 new breather on valve covers and within 30 minute ride they were soaked with oil. It is running about 70psi oil pressure to oil cooler with jesel valvetrain setup and at 600hp. that is info that might make difference or not... i'm not an engine guy.

Thanks...Keith

I'm not sure all PCV valves are the same. I believe different valves flow greater or lesser amounts whatever is in the crankcase. Flow too much and you may get too lean (a bad thing).

Bob

If you are running a high volume oil pump , you may be filling the valve covers with oil faster than it can drain back to the crankcase. This could cause the problem you are discribing with oil coming out of the cover breathers.

Neverwouldof - I believe almost all engines have some level of blow-by ie the rings don't seal perfectly. I also understand new engines will have higher levels of blow by until rings fully seat, and it's probably also affected by rings, pistons, tolerances, etc. Compression ratio probably also impacts it as well.

Obviously it's not a new issue or situation and you can see that on the original 427s it was addressed with a road draft tube and/or puke tank.

PCV was a pollution control mechanism that kept the vapor inside the engine instead of letting it vent to the atmosphere via straight breather or road tube. My own thought was that using the vacum source of the carb may make the PCV a little more effective since the vacum is drawing the pressure/vapors out of the crankcase vs just relying on the pressure to build up and it gave the vapor some place to go instead of the top of my valve covers!

If you think you're getting too much blow-by, then remember it's a symptom of how well your rings are sealing. Best thing is to then test your rings with a compression and/or leak down test. That will be the best indicator of how well your rings are sealing. If that's normal, then hopefully it's just a matter of getting a crank case ventilation approach that works.

Also, just because your breathers are soaked doesn't mean it's all blow-by. Lots of oil flying around in there and if you don't have a good baffle system, the oil is going to end up in the breather filters. I have a tall "goose-neck" breather on the back of my intake with a steel wool type mesh in the bottom and it was getting lots of oil coming out of it. Someone here at CC pointed out that since I'd gone to a hydraulic cam, there was a lot more oil being flung around in the lifter valley and it was probably contributing to the problem.

thanks for info...
 

Thanks for your info and i hope it's the latter of your reply. i just have std. push in breathers with no baffles that i know of. I'm going to take it to a performance engine shop around here and see what they can do. Not sure i have enough room to do any taller breathers but we'll see. I purchased this car in June and these are the specs of engine...

ENGINE

Assembled with ARP Fasteners

NOS 427 Sideoiler Block standard bore 4.233
Oil Gallery Restrictors Installed and Oiling System Blueprinted To Feed Lifter Galleries and Pump Oil Through Pushrods to top end. far superior to normal 427/FE System.
Relief Valve Shimmed to provide 60 PSI Oil pressure/idle
Block Honed, Line Bored, and trued/decked By Pat Musi Performance
10/10 428 CJ Crankshaft Internally Balanced and Micropolished
ESP Rods / ARP 8720 Rod Bolts
Diamond Racing Forged Pistons 10.25:1 Compression
Hoffman Machine H -13 Tool Steel Wristpins with dual circlips installed
Edelbrock MR Aluminum Heads Ported by Pat Musi Performance
Manley Severe Duty Stainless Valves 2.225/1.750
Crane Dual Valve Springs Retainers
Perfect Circle Teflon Valve Seals

Clevite Engine Bearings
Mellings High Volume Oil Pump
Heavy Duty Oil Pump Drive
Jeff Johnstone/ Billet Fabrication Custom Oil Pan and Windage Tray
Crane Solid Mechanical Roller Lifters
Crane R - 246 Mechanical Roller Cam 246/256 @.050 .580/.601 lift
Jesel Competition Pushrods
Jesel Custom Shaft Mount NASCAR Valvetrain
NOS Ford Flywheel
Edelbrock Aluminum Water Pump
MSD Billet Distributor
MSD 6A Ignition Control
McLeod High Torque Starter
Holley High Pressure Mechanical Fuel Pump
Black Powder Coated Fuel Rail
Original Ford Tunnel Wedge MR 427 Dual Quad Intake with pair of Original 735 Holley 4 BBl
Billet Remote Oil Fileter Mount/Braided Stainless hoses/AN Fittings throughout.
Aluminum Snorkel Breather
Pentroof 427 Valve Covers
Original 427 Harmonic Balancer
K&N Air Filters in Hellings Chrome Housings

Performance:Flywheel on Hoffman Dynomometer 603 HP @ 6700rpm /590 Ft Lbs @ 4800rpm stays at 180F all day long in traffic on a 90 degree day.

Sounds nice!
 

And, sounds like it's throwing it's fair share of oil around inside the top end. I think you just need the right baffles. Check out these breather restraints that you can get from Summit
http://www.clubcobra.com/photopost/d...cture_0041.jpg

It has a double o-ring inside and the bottom is baffled so it will make a better seal with your breather cap and the bottom helps keep the oil from getting directly on the breather filter or PCV valve in the breather cap.

Just search Summit under "breather restraint." They're made by CSR. If you can remove the valve covers, then you can probably manage to install these yourself. However, you may have to drill out the hole in your valve cover to a little bit larger size.

In my case yes I have a windage tray ,yes I may have overfilled the oil pan, I do have a high voluum oil pump with the optional shim installed. I haven't noticed any blow by before this incident. I think the proper oil level and the Mobil 1 having an antifoam additive will take care of the foam problem . The valve covers filling up may be a fact . Probably did so when it foamed.

neverwouldof, you've got an excellent motor, but you should be able to build more hp at a lower rpm. That may be with a different port job, cam or whatever. Be that as it may, if you have a rear breather, block it off as HSSS427 did; your engine is set up for hydraulic lifters, whether you're running them or not. Your engine builder doesn't understand the FE needs oil to the rocker shaft (yours has it, but is it enough? You have to have enough to cool the valvesprings in a street motor; this is accomplished by the restrictors under one of the rocker shaft studs on each side) and not through the pushrods to the top end. Unless your pushrods have holes all the way through them (most for FEs don't), oil isn't getting up there as they say anyway, which is good. It's not necessary. However, you've still got a lot of oil being thrown around under your intake, so don't use a rear breather; block it off. Use a baffle under a PCV valve on one valve cover with a hose running to the large tube in the base of the carb, and the oil-fill breather on the front of your intake as the entry point. If you need a baffle, do a search for HSSS427's post of his original problem; one is described in there, although the one he shows should work at least as well.

Dan