the PCV systems in new cars are pretty much the same mate.

every engine produces blow-by. Even new engines. Blow-by obviously increases with engine speed and load. And the gasses that do get past the rings into the crankcase contain unburnt fuel, as well as all the other stuff that normally finds its way into your exhaust. The purpose of the closed PCV system with regard to pollution (rather than ventillation) is to remove these vapours from the crankcase. There are a few problems with this unburnt fuel and waste burnt gasses being in the crankcase;
-its corrosive
-it degrades the lubrication properties of you engine oil
-contain unburnt HC

An engine in good condition will not vent oil through the PCV system in road use conditions.

The reason race cars do not use a closed PCV system is that they spend a much higher percentange of their running time at high load, high rpm conditons which equals high blowby and high crankcase pressures. In those situations an engine in good condition can vent some oil into the PCV system. Oil contamination of the air/fuel mix degrades the octane rating of the fuel which is obviously highly undesireable.

But as I said before, an engine in good condition used on public roads won't vent oil into the PCV system. If your engine is worn and producing too much blow-by, therfore increasing crankcase pressure, it will. Removing the PCV system is treating the symptom, not the problem. If you're really after peak efficiency and performance, consider a freshen up of the engine.

Quote:

yes i am saying that. lead was also a suppressant for many other chemicals and when heated it was, in itself, a catalyst.

removing the lead from fuel was a "damned if you do, damned if you don't" scenario. the general, ill educated and misinformed public and government ministers were more worried about lead (of which they know the effects) than benzyene or carbon monoxide or xenoflourocarbons or whatever (the effects are lesser known) so they banned lead and the catalyst effect with it.

i'll google for the proof and post it.

Quote: I gotta agree wholeheartedly with this.
In a road engine, the PCV is a practical & efficient solution to a very real problem & any power loss is negligible in anything but a max performance, all out, balls to the wall engine.
My engine is an improved performance road engine, & hell, i'm ADDING some polution control stuff, including a cat converter. It will not reduce my on-road performance by any degree that i will be able to notice & i can always proudly say that it is 'Clean Mean & Legal' Who else amongst us can join in this chorus?

I always remember that old man of racing, Ak Miller. He was not a young man, yet in the early 1970's he was winning in the Baja 1000, a semi off-road event, with a race vehicle that complied with the projected 1975 California smog laws, which were the toughest in the world at the time. I always regarded him as the thinking mans racer.
It was he who used the phrase," Old age & treachery shall always defeat youth & enthusiasm" He is /was an automotive icon.

Hy L18B110: In your posting you mentioned the following:
Quote:
Due to the nature of my job, I have to drive a lot within southern California(court/medical interpreter), to courts, Doctor offices, Law offices, patient/client residences, so I spend about 80 % of my driving time at high RPM, going about 65/70 MPH,it takes me 10 minutes to reach the highway(called freeway/expressway here), then, takes me 45 min to an hour of high RPM to get to my exit, then, about 10 min to reach destination, even less. If my engine was in bad shape, I would say so, no shame, that is why we like to talk and repair our cars, the reason for my selection of a open system is that I see it as inefficient, at least in my case,the PCV valve at high rpm is closed, due to low manifold vaccum, and the blowby goes into the carburetor the other way around...(once the low manifold vaccum can not open the PCV valve due to no strengh/low vacumm reading, the PCV valve stays closed, in that case the blowby has to exit anyways, regardless of the PCV valve conditions, so the flow reverses, and instead of sucking air through the valve cover hose to air filter entrance,being the other avenue of escape closed due to no vscumm enough to open the valve, this entrance becomes an exit, spewing bad air and oil directly into the carburetor, to the detriment of the air mixture.)...contaminating the air mixture, clogging the carb passages, doing all which is not intended for proper efficient intake of clean mixture into the carburetor. I do drive at high RPM because , unfortunatelly I should say, distances in California are enormous, just ask anybody leaving here, easilly a days drive can be more than 200miles/day, mostly freeway. If going surfing, Trestles, San Diego county, etc southwards is about 250 miles down the coast. Any local spot , of quality, will make you drive 100 miles at least round trip, so, in cases like this, PCV systems are just (while driving an older 70's Datsun) attacking your engine. And , one thing that I am sure, those contaminants entering the air/gasoline mix into the intake manifold and then into the cylinders is just plain simply terrible for your engine. Why go through the carefull concerned effort of installing a ignition system(MSD dist/control box for example), a better carburetor, better spark plugs, new gapping of plugs(to work with more efficient capacitor discharge ignition), cam, cyl head work, etc etc etc, only to sabotage all this efforts with oily contaminated oil entering the intake manifold? my words are for the performance oriented efficiency concerned driver, I am not trying to convert the religiously pollution concerned drivers, that is another story. If somebody is concerned about pollution, as I am, there is no argument, I never intended such conversion of anybody. I acknowledge pollution and the need for pollution controls. This is a particular case, a case of a brand of automobile not even in existence today, as Datsun, no more, and which cars, in very small numbers, and declining by the day, are not in a position to become no threat to the enviroment. Of all Datsuns running, I offered this insight for those who are into a better efficient performance, those who are for keeping those devices in place for pollution reasons, should do it, but the fact about what happens in the combustion chamber when oil and broken hot air invades a space in the cylinder which is meant for clean cool air mixed with vaporized gasoline is a fact that can not be ignored nor twisted by concerns about pollution. our cars, even with all those devices in place...(emergency air relief valve, air relief valve, CTO switch, antibackfire valve, check valve, air diverter valve,air pump, selenoid control switch, catalic converter,thermostatically controled vaccum valve, PCV valve, thermostatically controled air filter horn,3 way passage, EGR valve, EGR passage,heater valve, etc, etc, etc, all parts that a 75 Datsun has, and some more I can not remember, I became an expert , self taought while trying to smog my cars)...will never even compete with the emissions numbers of todays cars, not only because of the old technology, but because all those parts, even if sitting installed in your car, will not work, after about 30 years of continuos work, parts which are not available ever more new from any Nissan dealer.
I see two roads here, one for those who, with all due respect, choose to adhere to the letter of the law and keep those devices in place for ever,no matter what, and those who want efficiency and can analize the situation and decide which devices are just not working as intended, or are simply ruining the potential performance of your car. There is no in between, pollution concerns can not erase the fact that the pollution devices for a 1200, 120Y, 610, etc Datsun built in the 70's, although well intended, are just hindering on optimum performance(never said such car can not run, but not up to is potential)due to its older technology(devices), applied to the engine after it was designed without those devices into account, more over, no new parts in existence acrue to the problem of old pollution device technology....On the other hand, the need for efficiency is not going to erase the fact that we need pollution controls to keep the world in living healthy shape. I arrived to the conclusion that I want a efficient motor, the best it can be, and realize that although the need for pollution controls is here to stay, the age and inefficiency of those devices can only hinder on my engine performance and engine life. I can separate both sides of the equation and not get caught in a deadlock.
If we want to be so severe about the pollution devices, then, no Weber 32/36, no headers, no nothing, we all should be driving bone stock Datsuns. Those who think that runing a PCV system on a header/dual DCOE or 32/36, cammed engine, no catalic, etc are being good to the enviroment, please wake up. This is not about pollution vrs unti pollution, no confrontation, this is about plain performance. You guys can not negate the fact that clean air and gasoline mixture is the only requirement for the efficient combustion, I think I have explained several times my position about pollution devices, need for responsable care of the enviroment, and the particular situation we face with our Datsuns. No place for confusion. Either efficiency or pollution concern, choose your side.

Jaime.))))))))))))))))))))))))))))))))))

race cars run alot of the time at high rpm and high load.

highway driving is not comparable. It's a medium rpm and low load (cruise) condition. Oil should not be entering the PCV system in that situation, unless your engine has excessive blow-by.

Jaime, you may win the award for longest replies!

I'm not advocating to keep all the pollution controls. Certainly EGR and air pump are very bad for performance and fuel economy. I was just saying and still saying that removing the PCV valve isn't going to gain you even 1 horsepower unless something is wrong with the tune in the first place. If you know of magazine articles or dyno tests to prove otherwise, please share.

If the engine is in such bad shape that it dumps oil into the inlet side of the carbs while at highway cruise, then disconecting the PCV won't save it.
I have run my 1200GX untill it was obviously well worn, & i have yet to see any oil in the air filter housing.

Hy:
In Datsun 1200 l18 B110 wrote:Quote:
Racing is not comparable to highway driving, I agree with that, but pushing a stock (weber 32/36,headered only mods) A15 engine at 70 mhp is high rpm for this engine.I also should say, have low profile tires on the car, less diameter, keeps the RPM high. I have a vacuum gage conected permanently to my intake manifold,and at 70mph, it reads 8 in HG vac, low enough to prevent any opening of the PCV valve. In such a case , reverse flow happens, and all the bad stuff goes into the manifold anyways, this time thorough the carburetor(valve cover to carb connection). This is not a criusing condition which would happen if driving at about 40 mph, even 50, still some vacuum left at fifty, but weak, so the PCV valve , at this low but still present vacuum, is opening and closing intermitently.
Also, L18 and Dodgeman, you guys keep refering to an engine which is in need of repair, in bad shape, because oil goes through the PCV system. That is not correct, I said before, this motor is not bad, all, ALL engines transfer oil with the bad air, altogether into the manifold with the PCV system, because that is where it is coming from( this air), from the block, cranckcase, where oil is splattering and moving around, so, yes, there will always be oil, it is imposible to have a PCV or engine ventilation system without oil, unless you never really drive the car past 20 mph. See it for yourselves, check the stock air filter assembly ventilation filter(small filter which meets the valve cover hose at the air filter element, small plastic case with this filter element. ) unless you changed it within the past weeks, or unless you do not really drive the car, it will be black, oily. It is a fact, the hose is connected to an area where oil is the moving mass.The engine does not need to be old, bad, worn to ventilate some oil with the ventilation system.
Dgonzal, I will check some information , as you said, and bring it in. A quick one, Dess Hammil, "How to blueprint and rebuild a 4 cyl engine for performance" , I have that book, check out the section for cranckcase ventilation.
I will bring in some information. Those who choose to keep the PCV system, it is fine, your car will run, will show no problems, it is a matter of fact, is good air for your cylinders the best you can provide?...or it just does not matter, a little scrapped air/hot and gummy will not really hurt the engine, it is all fine. Some guys go through the trouble of fitting snorkels or just better positioning of the air filter,air ram, to get access to cool outside air for the intake(as opposed to warm , hot air from within the underhood area), hoping to get better combustion, well, what about the hot gummy stuff entering the same intake system via PCV valve?
Think about what is good for the igntion event in the cylinder, what is it requiered regarding temperature, quality and purity of the mix coming into the cylinder, is hot gummy air fit this requierements?
Never get upset my friends, I see this topic, as all the others, as healthy exchange of points of view, never see me or my statements with bad eyes, I enjoy discussing this topic and others.
Later((((((((((((((((((((((((((

Ok, pollution aside, I have my pcv valve hooked up because I have always thought that the negative pressure in the crankcase helped the rings seat better. I have heard that the pcv was developed as a pollution control device but that the ring sealing bit was an added bonus for performance. I agree that the contaminated air getting sucked in does nothing or even takes away from performance but there has to be some other performance benefit for having a pcv installed. Why do some race cars have a crankcase evacuation system installed that hooks up to the headers? I understand how it works but why do they go thru the trouble? (i'm not being a smart ass, i really don't know )

With my size tire, i cruise 80mph(128km/h) @ 4000rpm. If it's a flat highway, I'm at around 13in.hg.(sometimes 15, sometimes 10). I've stuck a vaccuum gauge on the valve cover hole while the engine idled. Manifold vac was 15, vavle cover vac was 5-6in. This reading from the valve cover went up a little when I replaced my dipstick with a better sealing handle. Also, no oil dripping from the breather.
I will, however, have a closer look at my #4 sparkplug. The #4 cyl sucks in everything from the pcv.

ps. Where would I hook up a pcv if I intall a tur... never mind

if you're at high rpm at 70 mph, get a 5 speed tranny, and/or larger rims, I have 15" rims on my 210 with 195x50x15's and they are nearly the same diameter as the original tires. with a weber 32/36 4th gear takes the needle off my 80 mph speedometer and the engine still has room to rev higher.

What final drive do you have? that might be dragging your top speed down.