Hay there just looking to seen if you need a pcv vlave on and engine or is a breather in each valve cover good?
Well, I'm sure you'll get many different answers to this, so here goes: PCV is more efficient, and keeps you from smelling crankcase gases, but is not very traditional. Unless your mill has lots of blow-by, breathers are fine and look better. I have a PCV system because I don't care how it looks.
Open engine car or p/u, run a breather, closed engine run a pcv. Thats what I think. Hell, its your car, run what you think! lol
A PCV system will keep the motor a lot cleaner inside. On a lot of motors you can hide pretty much all of the plumbing if you want to.
...and it also keeps the engine cleaner inside. The PCV also helps to pull condensation out of the engine when it warms up and keeps the oil from getting that milky residue that can show up on your engines dipstick and inside the valve covers. PCV was one of the better pollution control devices they ever came up with...because it addresses REAL problems.
P.V.C. stands for Positive Crankcase Ventilation, what does it do? it positively vents the crankcase, thereby reducing pressures in the crankcase.. do you need it? Maybe, maybe not. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o> While the engine is running, it builds pressure in the crankcase. If the engine was totally sealed, it would start leaking from various gaskets & seals. Older engines just used breathers in valve covers, in oil fill tubes or a “road pipe” to vent the crankcase in to the air, and that worked fine. Then, mostly because of emissions, they added P.C.V.s to vent the crankcase through the intake to try to burn off some of the crankcase vapors through the combustion process. <o></o> I had a 327 with “V” top valve covers. The way I did it was I went from the port on a carb base to a pcv drilled and fitted into the oil filler tube on the front of the intake. I welded in a bent piece of metal above the pcv so it wouldn't get oil poured in it when I changed oil. You can stuff a piece of insulation, a rolled up sock or your wife’s hair scrunchy down the tube (not to far!) to catch the oil vapors so they drip back down in to the crank case.<o></o>
A PCV takes a lotta pressure off the front & rear main seals. Keeps the leaks to a minimum on a hard working mill, specially if its fit kinda loose.
I have one PVC in each valve cover of my 348 Chev and have zero blowby from the stock breather/fill tube. Before PVC's I was oiling the firewall, windshield, my forehead...
Nobody likes an oily forehead. Everything I have built in the last 25 years has a PCV valve. It is up to you.
Thank, I ruming the old cal customs and they have NO hole. I'm out on the side mount alumin breather and haveing a hard time trying to put the pcv in. Would like to put in in the side if it will clear. really don't want to cut a hole, but I really don't want to look at it ether. Thanks.
My shop truck has the PCV valve in the back of the manifold, and Offy breathers on the covers. It is sitting in a baffled grommet, which, I believe, came from Moroso. It has a clear hose and it does NOT pull up oil, so let's not start that debate again. It is pretty well hidden.
I gotta agree with the general consensus here about running PCV Valves on everything. They're a great thing! Like stated above, they keep moisture from building up in the crankcase and making your oil look milky and white, they reduce pressure build-up and therefore reduce leaks from seals and gaskets, and heck, they just might even be a performance gain from the extra air that you are introducing into the engine! I've always been surprised though at car shows at how many people do it wrong! They might have a PCV in one valve cover but then nothing in the other valve cover for a 'clean' look. It's a fairly simple concept......PCV in one valve cover and a breather in the other valve cover so fresh air can circulate through the crankcase before going into the carb/intake. As far as people worried about a PCV Valve looking too modern or "non-traditional", that's a small price to pay for something so beneficial. I've seen, and done, some clever PCV installations by drilling a hole in the floor of the intake into the lifter valley behind the carburetor and then a short length of 3/8 hose into a vacuum source at the base of the carb or intake runner. This type of installation is pretty easy to do and looks very clean and unobtrusive.
I am away from my truck, camera, and pictures, but here is one from another thread: And the link to the grommet I used: http://www.summitracing.com/parts/MOR-68776
PCVs are a good idea. I like the idea of keeping my engine cleaner and making it last longer. I wanted to keep my valve covers solid and still run a PCV on my 390. I ran mine to where the road draft tube was and to a vacuum source in the carb spacer. It will be hidden under the air cleaner once it is all assembled.
you beat me to it. the pcv does'nt have to be seen as long as it is installed where it can evacuate the crankcase as long as it can't get it's hands on alot of oil.
I've seen a couple diff discrete installations Both had one end of the pcv installed on the top rear of the carb and a hole drilled in the back of the pass side valve cover and another one had a hole drilled on the intake side of the valve cover towards the rear. If you do install a pcv, make sure that there is a baffle/shroud shielding any direct stream of oil (say from a pushrod) from hitting the fitting. I had a friend build a nice 383 stroker motor and left off the screw in L shaped shroud on the inside of a cheap set of MT valve covers, it turns out the one of the pushrods lined up with the pcv hole. Burned a crap load of oil until it was found.
Negative crankcase pressure is a good thing. Promotes ring seal as well what has been said above. And... its the only car part I can think of that is workin' if it rattles.
Essentially a copy of Pontiac's V8 PCV system, just w/o the valley pan. You just need a fresh air breather up top. Nice job!
Yup, what he said. This is probably the ONLY emissions thing ever made that actually improves the system. (Aside from electronically controlled fuel injection and electronic spark control and... but that ain't traditional, I know already.... shut up)
I don't have a pic available but I run one on my 1940 flathead. Vacuum source is from a spacer between carb and manifold that was originally used to provide vacuum to power brakes on large trucks. It is made of brass. I drilled a hole in the cover of the oil fill cover that sits on top of the original fuel pump mount, large enough to accept the rubber grommet that the pcv fits in. The pcv I used has a right angle bend, which is where the hose from the vacuum source connects. It works really well, and stops the smoke cloud from under the hood that used to appear when idling and no air was moving past the road draft tube.
The most misunderstood system on a car by the average guy. It doesn't suck a vacuum in the crankcase...it pulls fresh air through the crankcase removing the harmful blowby gasses and condensation. If all you provide is vents, the gasses and moisture mix together and become acids. Do you really want to leave those acids and moisture in the engine? They figured that out in the 40s. Notice that the AIR FLOW is shown using arrows. This is a 48-53 flathead Ford. There were air flow systems (road draft systems) long before PCV systems. I've read that people think that the "vacuum" makes the rings seal better. That's just plain BS. You can't pull a vacuum on a crankcase with air flowing through it. That is the purpose...a positive air flow though the engine. We've all seen the chocolate milk shake when water gets mixed with oil. We used to see that shit all the time in valve covers on poorly maintained cars and it was a sure sign that the PCV system had a problem. The condensation would build up and mix with the oil and you get the chocolate milk shake. I shudder when I think about it. Why do we change our oil when we have a filter on it? It's the same deal... acids build up in the oil and we remove them when we change it. Don't leave that shit in your engine. A PCV system removes the ingredients before it can develop keeping your engine clean inside.
Also helps with ring flutter. Most of the fellas probably won't be too concerned with that. Do ya need one? I probably wouldn't run without one and I was around before they were common. If your mill is old enough to have a road draft tube then you can plug one in there and not screw up those beautiful period perfect rocker covers. If your mill is too new to have a road draft tube then you probably need a PCV valve. On a different note the other day I was looking at an old blower motor, it didn't have breathers on the rocker covers and was too old to be running a vac pump so I took a closer look. They had angled Moon breathers on the oil pan. Pretty interesting and I'm not charging any extra for the tid bit.
I'v been wondering about this topic also - I have a set of finned "Corvette" valvecovers and want to run 'em on my '85 350 . Can the fuel pump block off plate be tapped and utilized for a pvc location ? I would use an Edelbrock Performer intake with the oilfill tube in the front and use a breather cap on the fill tube . Would this work ?
I removed one from my ot car and put it back in less than a year later. The valve covers would get blow by on them without it.
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