I am trying to decide if I am going to run my PCV system or not. Every stock TPI intake that I have seen taken apart had MAD amounts of oil coating the runners and additional sludge built up in the plenum. I have spent countless hours porting and fully polishing my Superram inside and having any kind of sludge and oil is unacceptable for me. I have read a ton of posts as I have searched on this topic but am still unsure on whether or not removing the PCV sytem could actually cause engine damage. Questions: Will all brand new PCV parts, hoses and valve, replaced at very regular intervals keep the oil out of the intake? I have seen a bunch of cars with dual breathers and no PCV system, are they doing something that I am missing or did they just dump the PCV system and are they at risk of damage? I imagine it does but will the oil that builds up in the intake actually hurt airflow or am I worried over nothing? Anyway when I have the car all put back together here in a couple of weeks it will be a garage queen and never a daily driven vehicle. The motor is a 383 with all the the bells and whistles of performance maching and building so all the internals are new and in proper spec. I know the main reason for PCV is to pull nasty air from the crankcase yada yada yada. My car probably wont see anymore than a few thousand miles per year and changing the oil will be more like a hobby for me versus a necesity. All opinions welcome.

removing the PCV should not put you at risk of damage,
if excessive pressure built up, you could experience problems
but I have not heard of this happening, ever. without PCV
I'd change my oil a little more often than usual, cause it'll
get contanimated with different stuff from the combustion
process.

no, no real adverse affects from removing the PCV valve that
I know of, just oil gets dirty quicker. slighty quicker? not sure
how much faster, but I wouldn't sweat it.

So its mostly a question of contamination not pressure?

Get some valve covers with the proper baffles in them and your PCV oil sucking days will be over. Most aftermarket valve covers either don;t have baffles and or the hole in the cover is in the wrong spot, allowing a rocker to squirt oil directly on the baffle.

The idle calibration is designed to allow for the small air leak that the pcv system allows. Pluggin it will enrichen the idle and off idle. Cars always run better and last longer with a properly functioning PCV.

You CAN dump your PCV system, if you don't mind changing your oil every month or 500 miles. You can burn a new PROM to recal the idle tables. The buildup in your intake will take longer to accumulate without the oil vapors, but will still accumulate anyway. Any buildup that you don't get in your plenum will more than be compensated for by the extra sludge in your crankcase. It's your call.

Yes it's mostly a question of contamination, and as
Vader and F-bird have pointed out, the issue is more serious
than I originally believed it to be.

as they've pointed out, keep the PCV.

A trick that works on fNords is to put a clear plastic fuel filter inline with the PVC hose. This way the filter can trap most of the oil and you can at least have a chance to keep the TB and runners clean. It does work and has proven its self many times.

SSC

The inline filter idea doesnt sound to bad. Does this stop all the oil from entering the plenum or does it still allow some by? So if I were to do this I would keep the PCV valve and run the filter with it while ditching the passenger side lin to the TB and using a breather instead?

Vader

Are you quoting the 500 mile oil change from experience? That number seems damn low but if thats the way it is thats the way it is?

Keep the PVC. It's not some emmisions device that is robbing power. It has a purpose--to help keep the oil/crankcase clean by venting the crankcase. Removing the PCV system to keep the engine 'cleaner' is backwords thinking IMO. Maybe you need to consider a vacuum pump to vent the crankcase(instead of using the engine vacuum to do so).

82camaro

I am aware that there is no parasitic loss due to the PCV system, my main concern is the spreading of oil all over the runners of my ported and polished Superram.

Have you ever seen a vaccum pump used for this purpose?

It was also just suggested to me that I could plumb a PCV valve into a line that would be fabbed into the exhaust after the O2 sensor, what does anyone think of that idea?

It does keep the manifold clean if you replace the filter once in awhile, every six months or so depending on how dirty the filter gets. Thats why I suggest using a clear paper element fuel filter.

If you hooked up the PVC system to the exhuast it wouldent work, you need suction provided by manifold vacuum.

OK, this is something I don't understand. People always say removing your pcv will cause your crankcase to not be vented, but what the hell is a breather for then? Doesn't a breather just perform the same function as a pcv, except the fumes and gasses are vented into the atmosphere instead of into the engine to be burnt again. I understand how running valve covers with no provisions for any venting could hurt the engine and cause the oil to be contaminated, but I don't understand how removing the pcv and replacing it with a breather can hurt the engine at all.

PCV=positive crankcase ventilation

Manifold vaccum is applied through the PCV valve so all the nasty crap gets sucked into the intake and burned in the combustion process, only problem is it turns your intake into an oil slick. Good for the crankcase bad for keeping the inside of the intake clean.

I understand this, but I dont understand why you can't just remove your pcv valve entirely and replace it with a breather and cap where the line goes on your throttle body. Your engine would still be vented and you wouldn't be sucking the fumes into the engine, but instead venting them into the atmosphere. Am I wrong on my thinking? What is so bad about replacing the pcv valve with a breather besides the pollution aspect?

if i understand correctly it isnt the gasses its the fact that all that oil crap that gets in your intake doesnt its just sits in the crank case and it needs to be gotten rid of. My question is if this is the case how do some cars use breathers?

I agree about keeping the PCV in place. If someone has a properly working PCV system and they think they need to change it to breathers, in order to help crankcase ventilation, they've got more problems then they would probably care to know aka major blowby. If you just want to switch to breathers because of airflow purposes, I don't think that enough oil would accumulate using the PCV to affect performance. Well maybe after 100,000 miles or something. If you had oil collecting on the valve from leaking seals, that's a different story. I've seen valves with what liked a couple millimeters of oil caked on them. I guarentee that that affected performance.

Oh yeah, I don't think your oil change schedule will need to be changed to every 500 miles if you run breathers. That's rather extreme. The main reason I would just stick with the PCV system is that Breathers STINK, especially when you go WOT. I have seen some guys run one breather and one pcv valve that went to the throttle body.

I never ran pcv on my new motor after I built it.

8k miles later the motor was on an engine stand so I could change the oil pan gasket, rear main seal, timing chain cover gasket, and valve cover gaskets. The only fricking place that didn't have oil squirting out was the fuel pump block-off gasket.

Now I run pcv.

Did you have it completely blocked off or did you have breathers? What I am not understanding is why you would hurt your engine if you ran one breather on each valve cover. That way you would still be venting the crankcase pressure and not have it going back into the engine. Why is this bad? I am asking an honest question so someone could please explain this to me. A PCV valve is used to vent the gasses and fumes that build up in the crankcase of an engine correct? A breather is used for the exact same purpose correct? Other than polluting the environment, why is running breathers instead of a pcv system bad?

True, breathers vent into the atmosphere, but only what is pushed. The benefit of PCV is the constant vaccum that is applied aiding in the release of condensation and other contaminents.

Replacing a straight fitting for the pcv system into a catch can/breather or an inline fuel filter fitting is a very good idea... Should there be blow-by etc the oil isn't recycled to be burned thereby keeping your intake charge less contaminated and your runners etc cleaner.
If you run NO PCV system then you'll have the problems Jim described... If the crank case can't vent you're not going to be happy for long. If the dirty oil is removed entirely there's no reason to think that it would cause any harm as it's no longer in the engine, just like pcv is intended, except instead of being burnt it's being removed.
Some might say it's not necessary "if everything is in good shape." My response to that is that all engines blow some oil occasionally through the pcv system, this makes things dirty. While it might not affect it in the short term after 20-30k miles it does begin to build up. There is no reason not to run a fuel filter in line with the pcv system (Purolater F23170 fuel filter should work as I recall) with some small band clamps to hold it on. If you're feeling really ambitious an external vented catch can (Summit part SUM-G1505 basically a piece of pcv pipe with a breather on top to allow for proper crank case ventilation to allow for more time between filter changes.) I wouldn't really recommend straight K&Ns in place of the pcv due to the fact that it allows oil to be blown all over your whole engine compartment, basically not good for anybody who wants to keep their engine bay in show quality cleanliness.
In short, overall the pcv system is good, use an inline fuel filter or catch can to keep everything clean.

I'm old enough to have actually owned cars where the engines ONLY had breather caps instead of a PCV valve. Instead of oil accumulating in your intake, you'll be wiping oil off your engine constantly.

Your choice.

I had a breather in each valve cover.

I like this idea....i dont have a show car but whenever i have to rip apart the tpi to do something its all covered in black on the inside and i just dont like it. For the catch can is it as simple as just hooking up the tubing to a can and the extra oil can spill into there?

Alright, now please don't take this as a flame because it is definitely not intended as one, but I am confused. I assume you attributed your problems with your engine to having no pcv, and instead breathers. Correct me if I'm wrong, but wouldn't having breathers still allow your engine to vent the crankcase? How would not having a pcv cause you problems? Again, no flame intended, just an honest question. BTW, was there any excessive sludge buildup inside?

Pretty much, yea. Replace the pcv valve with a straight fitting and run a piece of tubing to your catch can instead of to your intake manifold, simple enough.
The inline fuel filter is probably just as good as it doesn't "defeat emissions" as rerouting the pcv hose is considered to be. In my opinion unless your breather is inoperative/plugged etc I'd think the extra crank case ventilation would actually help rather than hinder... The pcv valve shuts when you're on the throttle anyway (since the vacuum would probably pull even More oil into the intake) so having it able to vent while on the throttle would most likely help.
Of course using a catch can is mostly necessary for people running some type of boost (nitrous supercharger turbo etc) Most of the time it's not necessary when running n/a and the fuel filter in-line would be the better option.

I agree with Glenn here. I run duel pvcs on my race car. I raced 30 years ago, with no pvc system, two vents on each valve cover, and still had oil everywhere. Go to the track and look at some cars, you can always spot the ones that run breathers instead of the pvc system. On a new engine, that is sealed good, crud in the intake would be minamal. By the way, my race car doesn't leak oil.

I'm not argueing the fact that breathers might make a mess or that they might stink a little, or that even using a pcv won't cause massive amounts of sludge in your intake. I have just read numerous times before from doing searches that by running breathers you will some how hurt your engine. I don't see how this is possible. Can someone shed some light on this for me please? If you think about it, using breathers might even enable your engine to vent MORE than a pcv. So can you really damage your engine by ditching the pcv and going the breather route?

When there's crankcase pressure being built up, it's from compression that's supposed to be in the cylinders (aka blow-by). Every engine has it, even new ones. It's just that 'tired' engines blow more. The only exception I could see are those gapless rings, but how many of us run those.

Anywho, the hydrocarbons (unburnt fuel) is vented either into the atmosphere (feds no like) or into the intake system (feds like).

If you get oil all over your engine from running vents, then you have major blow-by. How do I know? My '72 has them and I'm always whiping off the valve covers. Obviously I have a lot of blow by because I do this EVERY TIME I drive it. And it's not just a little oil. It's quite a bit.

The drawback of running it into the intake system is carbon build up. Look at the tops of valves from an engine that had leaky valve seals. They will be caked with carbon. The carbon from oil burning is much higher than gasoline. If you have major blowby, and a PCV system, then expect excessive carbon deposits to form inside.

I like the fuel filter idea, except it would seem like it would get clogged rather fast. Once that filter is clogged, you may as well not even have a PCV system there. It would be the same as not venting the crankcase at all, wouldn't it?

IIRC, that's why they make the filters that go on the end of the PCV tube an into the air cleaners. They're made outta different stuff than fuel filters.

Clogging/saturation is always a concern but provided the engine is in relatively good shape you should get a few months out of it, if it's blowing by a quart a day then of course an oil separator or something similar would be a necessity, but the filters have been used with great success on several other types of cars as you might see on other messageboards. I don't see why it would be any different on a small block chevy. I run a catch can myself, no problems with it or anything so I don't know why breathers would destroy an engine...

I looked at the catch can. My question is how exactly do you plumb it inline? It appears to have a filter and 1 port on it. I imagine that you put a hose from the PCV valve to the port on the can and then somehow tie vaccum into the can? But even putting vaccum on the can seems like a difficult task as it would suck right through the breather on the can???

Please explain.

Catch can.

I didn't mean placing it in line but rather as a simple oil catch/breather, which is why I said to use a straight fitting instead of a pcv, so that the oil that would normally just blow through your engine bay with a breather would instead be gathered in one spot (much cleaner in other words) Only the fuel filter can be used in line. I believe there are spots for 2 inlets though so you could vent both valve covers, but again this would require the pcv fitting on the intake manifold to be plugged.

I see, so you are only using it to catch oil blowby instead of having the oil splash all over your valve covers. You are not actually applying any vaccum to the crankcase with your setup.

I however desire to have vaccum applied in my situation. What I will do is take your idea and mod it. I will fab up my own catch can. Sealed with 2 ports and a drain, no filter.

1. I will run hose from the intake manifold to a port on top of the can to apply vaccum.
2. I will run hose from the PCV valve in the valve cover to to a port located mid can to deposit sludge in can.
3. I will pack the top half of the can with some material to act as a filter.

I think this will work out real nice, should cost about 10$ at Home Depot for parts.

I've used the coarse stainless steel pot scrubbing pads for the filter. Then put a small piece of foam over it to prevent the possibility of a strand being pulled into the engine.

Just adding the catch can will reduce the amount of oil being pulled from the valve cover. This is due to the reduction in strong pulses being applied to the PCV system at the valve cover. The can acts as a dampener.

RBob.

So you're basically going to be running a homemade oil seperator then? Let us know how it works, and be sure to post a tech article if it works well I didn't really feel the need to recirculate the "dirty" air so the catch can was better than just venting to the engine bay but I'd like to see how it works out for you.

I say run the clear fuel filter....I did that when I owned my 1995 Eagle Talon, Turbo 2.0, AWD...

It worked...plain and simple...just change it at every or every other oil change...whenever it gets full...so much simpler than any other solution and guaranteed to keep the intake clean

Oh...and keep the PCV...it is there for a reason...to relieve and/or equalize crankcase pressure...think of the engine as a large air pump and realize why you want the pressure equalized

mine was unplugged tonight by mistake and my car for sh1t...realized something was wrong I found the pcv and plugged it in...car ran perfect....keep it

had similar experience last week with my brothers 78 TA...he had unplugged and I plugged it back in and it cleared up his idle

Running a PCV as opposed to just breathers is better for the eng.

If you're running breathers only, the crankcase fumes are vented alright.
Problem is, they are replaced by more fumes.

With a PCV, the fumes are vented and replaced by clean air.

A TPI eng, that's in decent shape, shouldn't have any oil fumes traveling into the plunum or runners. The tube that connects the pass side valve cover to the throttle body flows air from the throttle body INTO the valve cover. If you pull this line off at the TB, and smoke comes out with eng idling, there's a problem. Either the PCV system isn't working properly, or there's simply too much blow-by.

The PCV does allow fumes to enter the intake manifold, but not the plenum or runners.

I'm skeptical abt running a fuel filter inline with the PCV.
My concern is the filter media becoming saturated with oil, and not being able to flow sufficiently to prevent excessive crankcase pressurization during high power situations when blow-by is at its peak.
The PCV is made to flow small amounts of air under high intake vacuum conditions, like idle.
When intake vacuum drops (like under accel (with higher blow-by)), the little ball inside the valve drops and allows much more volume to pass.

I'm suprised no-one has mentioned the ol'fashioned draft tube.
It wouldn't be legal on a street car (ahem), but it does create a low pressure to pull fumes out of crancase. A breather on the other valve cover would allow filtered air in to replace the fumes.
Problem with this (other than the legality aspect), the oil mist from the tube promotes the formation of gunk on the underside.
Also, the local drag strip officials might not appreciate you blowing oil mist down track.

I wouldn't try plumbing the crankcase air into the exhaust either.
Unless you properly designed a set-up that used exhaust gasses to create a low press area (using a venturi of some sort), I'm afraid you would simply be allowing exhaust to flow into the crankcase. That would be really ugly.

This is my setup and I dont have any oil in my throttle body or intake. I use the PCV and a breather on the driverside (breather is a vent/oil fill cap and the PVC goes into the intake like the factory had it setup). On the passenger side, there is a vent that goes into the throttle body.

Here's a couple pics:

Passenger side vent to TB:

well i have a 305 carbed, i put on a edelbrock air cleaner and breather that i have hooked up to a banjo fitting in the air cleaner....i dont know if this works but it came with the banjo fitting so i used it there on the passenger side and kept the pcv setup as well....im just not sure how the fumes will stay in there seeing as its an open element...

crank case ventilation is just that "ventilation"

like opening a window on each end of your house to let "flow" remove the hot stuffy or smoky air and to allow fresh air in.

PCV (positive crankcase ventilation) means it is ensuring "positively" that fresh air is ventilating in. I have seen people run two breathers and no breathers and just the vac PCV line and valve. niether perform this function other to merely "release" the pressure which is not what this system is supposed to do. this system is suppose to remove the oil vaporous air, not just "vent" it. alot of this is caused merely by windage not always just exhaust contamination of the crankcase.

When you build a power adder car you have to run a looser ring endgap to keep them from butting for a myriad of reasons not just RPM. this and the higher cylinder pressures caused by boost or nitrous adds to the problem. so wiping down the engine and the rest of the compartment can become a real drag after a while. also the smoke from the oil mist hitting the headers makes your car look like shat all the time.

I have always used a vent catch can like the one shown above on the one valve cover to allow cool fresh air in and stop oil from blowing out of the vent filter, and on the opposite valve cover the pcv valve, even on a 800+ RW HP EFI'd drag car. The factory put alot of thought and testing into this basic PCV setup and it is used in many types of internal combustion motors made all over the world. I think it gets the job done on many levels.

As an example here is a pic of what I mean, and it can be used with or without the vacuum side catch can:

I run a crankcase evacuation system (goes from valve covers --> check ball -> headers) The crankcase gases are sucked out by the exhaust.

Breathers let the vapors flow out under their own power, which means not much guck and goo and other stuff that used to be oil is coming out.

The PVC system, however, uses engine vacuum to SUCK all that stuff out, so it will stay alot healthier inside the engine.

Plus... its alot easier to remove and clean and intake manifold than to strip and entire engine to bare bolts and clean it all.

I have stripped litterally everything off my 350 as far as emittions goes, but the PVC is still there and works like a charm. The engine was clean every time i've taken off the valve covers (2 times this summer alone) and the oil that came out when I did an oil change was minty clean and was not looking like cottage cheese like it might if you do dump the PVC.

And on my engine its just the PVC valve in the valve cover and a hose on that going directly to the carb, so it isn't in the way or an unsightly thing to see, because its just one ~8" long hose to the valve cover.

A carbed setup is no way like that of FI. With a carb there is always fuel in the intake charge which reduces any buildup from the oil vapor. FI is air charge only so all kinds of shiit can build up inthe intake.

Like apples and oranges.

so very true

yeah I forgot one other cool deal about PCV's

A few times I have seen cars that if you disconnected the pcv they would just start drip-drip-dripping on the ground almost instantly! A pcv can actually help prevent leaks! once a car was in the shop that would do this I would show about a dozen people including other mechanics, customers, and friends that came by.

I have a question about this set up...

Why can't the tube from the filtered air cleaner to the job instead of having the catch can on the intake part of the PCV system???

I like the catch can on the vent from the cranckcase used in conjuction with the PCV Valve and into the Intake. This seems best to me.

The Fuel Filter is also another interesting idea as well, but seems it clogs to frequently and would be required every oil change Where the catch can you described seems more effective in the long run.

Again, why have two catch can instead of using the filtered air from the air cleaner as the intake to the ventalation?

Would putting a fuel filter inline after the second catch can be counter productive?

(I am studding emmissions system now and after fully understanding the system I wondered why/how people used the breather filters I seen so much on these forums)

You know the PCV valve only needs a slight vacuum to pull the crud out of the engine.

I have heard of this, it solves the problem of needing a filter, getting your intake dirty, and fabbing up some filter job.

Take the hose from the PCV valve, and route it down to your exhaust, below the headers, put it in at angle where it is facing downstream of the exhaust flow.

This will create a slight vacuum, pulling the gasses out of your top end, and dumping them into the exhaust to be burnt/catalized.

Most likey you wont be able to use simple rubber for the hose connecting to the exhaust tho..