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Old 07-11-2007, 02:14 PM
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PCV setup

I've recently built a stroker 305 that I'm going to be putting into an '80 Regal. The build is pretty mild, like I said its a bored and stroked 305 with a mild cam, Vortec Heads, Air Gap intake and 650 cfm Holley carb. My question is about running a PCV valve. My friends tell me that I have to run one, but couldn't I get away with just running a breather on the valve cover? I always thought PCV valves help release gas that builds up in the crankcase, and that a breather would remedy that. If I do have to run a PCV valve, does anyone have any suggestions on how to go about doing that? Is there a system I may be able to find in a junkyard or elsewhere for cheap?

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Old 07-11-2007, 02:26 PM
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I recommend using one, and why is because it helps keep the oil cleaner, blow by gasses will "fall" into the oil when there is no pcv valve, and we all know fuel in the oil isn`t good. Sure you could just use the vents, and while it`s free vented will push some of the blow by out, it won`t get as much as the pcv will. I don`t see what`s hard about setting up a pcv, if you have valve covers with the gromments you just get the push in pcv and connect it to the vacuum source. Place a breather on the other valve cover. If you run it without a breather it will pull too much vacuum and suck in oil also. I played around with pcv`s enough to find that they must have the breather, as it acts as a restrictor. All you`ll need is the correct pcv valve, a piece of 3/8 vacuum hose connected to a 3/8 vacuum port, the correct gromment in the valve cover, and a breather on the other valve cover, simple and won`t cost you anymore than maybe $15.
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Old 07-11-2007, 02:37 PM
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"stroker 305". Is that an oxymoron like "giant shrimp"? Just kidding.

Millions of small block Chevy's were in everyday use with just a draft tube to atmosphere to vent crankcase pressure before OEM's went to PCV (possibly from pressure from the EPA???). I may be wrong, but I think the PCV has to do with introducing spent fumes into the motor to lower oxides of nitrogen to meet emissions standards. More millions have been run on the street with just a breather on the valve cover. You'll probably get varied opinions on this, but I would think that unless you have to conform to emissions standards in Taxachussets, a valve cover breather would work fine.

I was typing this while doublevision was posting. I like his answer better.
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Old 07-11-2007, 02:55 PM
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I agree with what DV said. Sure it's ok to just vent to the atmosphere but the PCV system will keep your engine and engine bay a little cleaner as well. I know I don't like to spend any extra time cleaning mine.

This is one of those threads where it could go on and on with everyone's opinion. I run a PCV, and it's cheap, as long as you don't have to buy new valve covers to make it work ........there, that's my opinion.
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Old 07-11-2007, 05:58 PM
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Quote:
Originally Posted by Nalehed
I've recently built a stroker 305 that I'm going to be putting into an '80 Regal. The build is pretty mild, like I said its a bored and stroked 305 with a mild cam, Vortec Heads, Air Gap intake and 650 cfm Holley carb. My question is about running a PCV valve. My friends tell me that I have to run one, but couldn't I get away with just running a breather on the valve cover? I always thought PCV valves help release gas that builds up in the crankcase, and that a breather would remedy that. If I do have to run a PCV valve, does anyone have any suggestions on how to go about doing that? Is there a system I may be able to find in a junkyard or elsewhere for cheap?
I thought Massachusetts subscribed to California emission standards. If so that means a PCV set up is required for a street driven 80 Regal.

Actually a PCV is a vast improvement over road tube breathers especially on a new engine. They pull a slight vacuum on the crank case which helps with ring seal which reduces blow by.

While many people think the PCV pulls oil vapor into the engine, this only occurs on engines ready for the grave yard. What's in the crankcase is combustion vapors that get around the ring pack. This is mostly unburnt fuel and water vapor. Pulling this stuff back into the intake helps combust the unburnt fuel and gives everything another chance to go out the exhaust. These things greatly extend engine life as a result.

A proper and legal configuration is a closed breather system where a PCV valve connects, usually from a valve cover to the intake below the carb or throttle body. On the other side is a hose that connects a valve cover to the air filter housing, this may be outside or inside the air filter itself. I prefer to pull thru the filter, but many designs are on the intake side of the filter.

Such a system can be put together from parts store components. You'll need a PCV valve appropriate to your engine. Some hose adequate to make the connections. Grommets and fittings, perhaps breathers, necessary to make the hose connections between the rocker covers and air cleaner housing for the fresh air side and between the rocker cover and intake manifold on the PCV valve side.

For a street engine, the factory air cleaner housing with an enlarged snorkel tube connected to an outside the engine room source of cold air with a K&N replacement for the paper element is a very good choice. The enlarged snorkel improves how much air you can get into the housing. A connection from the snorkel gets outside air which in the summer can be a 100 degrees cooler. The advantage of this is that every 10 degree drop in air temp at the air horn is worth nearly 1% on torque and HP. So a 100 degree drop in inlet air temp is worth a 10% power improvement. That's a lot of power for real cheap. The K&N filter replacement provides more CFMs compared to a paper element with better grit trapping ability. Plus they're cleanable and reusable which after a couple/three paper jobs you didn't replace pays for the K&N.

This is a win-win all around.

Bogie
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Old 07-11-2007, 06:41 PM
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Dang it Bogie...........now I want to pipe in outside air. You are correct though, cooler air is thicker and all normally aspirated engines love it. Just have to figure out how to make this look good under the hood. I've got an aluminum 2x14 filter on there now.

I know, I know, bust out the Jegs catalog, problem is, ya gotta bust out the checkbook and I got other items on the list.

Thanks for the education!!
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Old 07-11-2007, 09:29 PM
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I took apart a '59 283 that had right around 100,000 miles on it, bought from a friend whose parents were the original owners of the car. It had the road draft tube, no PCV. There was so much crusty black stuff built up in the valve covers that it looked like somebody carved impressions in it just so the rocker arms had room to move. I've never seen anything close to buildup like that in a motor with a PCV system, not even in the same league. No, PCV is not necessary, and a motor without it can idle at some unbelievably low rpm figures if you're into that kind of thing, but do you really want stuff like that growing in your engine? I don't.
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Old 07-11-2007, 09:50 PM
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PCV isn't just an EPA thing, its the greatest thing to hit engine and oil reliability since... well, the PCV valve.

Absolutely run one. They cost absolutely zero power (in fact they sometimes make power) and extend oil life and engine health by leaps and bounds. The key word in positive crankcase ventilation is "positive." It actively removes oil contaminants and also helps ring seal.

Not running one is (at the risk of sounding like a jerk) just stupid. They are truly a win-win part. Not to mention they are super simple. Plug them in, run a 3/8" fuel hose to a manifold source on the carb or the intake and you're done.

I suggest that you run one, change your oil at 5000 miles and be happy. OR-- don't run one, change your oil at 1000 miles and wonder why your plugs foul, your engine burns AND leaks oil, and there is this weird grey sludge on your oil cap. Pretty simple choice if you ask me.
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