The Stovebolt Site Forums The Shop Area Engine Shop My PCV Valve Install

With the prospect of driving my daughter in several parades this summer, I decided that this was the year to add a PCV system to the 235 in the '51. I'm usually one to figure things like this out on my own, and this case was no different. I did some research and found a couple of different procedures to add the PCV, but I wasn't really happy with some aspects. I also had some good advice from someone whose opinion I respect. I wanted to find something that didn't require much investment, or any special parts or tools. This is what I came up with.

I started out at my FLAPS. I picked up a PCV valve. I didn't pay attention to which one. As far as I can discern, there isn't much difference in them except the mounting hole size or hose size. I also picked up an oil filler cap for an early '70's F*** truck (Murray p/n 8071). This cap is non-vented, contains gauze filter material inside and has a mounting hole in the top for the PCV valve. I also picked up a length of hose and a fitting to connect to the vacuum port on the intake manifold. I won't bore you with installation instructions for that. I think you all can figure that out.

For the fresh air intake, I decided to use the road draft tube. Well, part of the road draft tube, anyway. One of my parts engines had the tube removed from the breather. I used this one, because I was concerned that highway driving would leave the draft tube and PCV competing, and the engine loosing all ventilation. After a couple of weeks of soaking in gasoline to loosen and remove all of the built up sludge, I painted the tube. Next, I installed some gauze type filter media that I found at the FLAPS (Micro-Gard p/n 42998BP). I wanted to do this because, even though the tube was baffled, I didn't feel the baffeling would provide adequate filtration to the incoming air. This gauze filter is the same type that was used in PCV filters on older carbureted vehicles.

I think that the end result will give a good air flow through the engine without too many modifications.

I'm open to comments, but please be kind...




http://s247.photobucket.com/albums/gg136/8trackdude/PCV%20Valve/

I've been thinking of adding a PCV mainly to contain the fumes coming out of the rocker cover after the engine is shut off(due to complaints the garage "stinks" - personally I like that old car smell). Your set-up looks very clear cut. Do you get smoke/fumes out of the crankcase breather after you shut off the engine? Thanks.

I think you have it wrong way round Tim, you should be sucking the fumes out of the road draft and allowing fresh air into the oil fill cap - that's the way the factory does it and why it's called "positive crankcase ventilation" .... when moving, the road draft tube draws air out, so you'll only have air in when sitting at an idle, and there's not really much in the way of fumes in the top cover

same for you Dave, the PCV won't have any effect on what you smell after the engine is shut off, and any vapor you see from the rocker cover will be primarily water vapor - more likely the garage smells like the exhaust fumes and leaking fluids evaporating from the outside of the hot engine

Bill

Im with Red. I'm running a PCV valve in the Road draft tube where you have the fresh air comming in. Use a breather cap or filtered air from air cleaner. That's the way factory PCV (i.e. 261) plumbed it.

Positive airflow works either way- - - -the system doesn't really care which way the air gets into the engine. Internally, a PCV valve consists of a spring-loaded tapered plug that takes small gulps of air from the crankcase (or valve cover) as the manifold vacuum pulsates slightly between intake strokes. Otherwise, there would just be a massive vacuum leak and the engine wouldn't idle worth a flip. Getting clean, filtered air into the engine is the trick, either by adding a filter at the inlet, or just pulling air from the "clean" side of the main air cleaner. That's how we did thousands of conversions to PCV in California back in the 1970's when the California Air Resources Board ("CARB"- - - -how's that for irony?) decreed that all engines on California roads had to be retrofitted for sealed crankcase ventilation systems.
Jerry

I pondered this for quite a while. I know the OEM PCV system vented from the draft tube. I also know that others have retrofitted their engine with the PCV valve in the draft tube location. But, on the other hand, more "modern" engines like the 230/250/292 put both the PCV valve and the fresh air intake in the valve cover. Like Jerry said, it doesn't matter where the things are located, as long as there is a vacuum side and a fresh air side.

I am pretty sure there was an early GMC setup that had the air intake at the draft tube location. I mounted my PCV there and I use a vented oil cap.

Here is a couple photos of mine. Worked out real good.

http://talk.classicparts.com/picture.php?albumid=180&pictureid=1812

http://talk.classicparts.com/picture.php?albumid=180&pictureid=1811

http://talk.classicparts.com/picture.php?albumid=180&pictureid=1810

Old Set up Photos

http://talk.classicparts.com/picture.php?albumid=180&pictureid=1523

http://talk.classicparts.com/picture.php?albumid=180&pictureid=1522

http://talk.classicparts.com/picture.php?albumid=180&pictureid=1521

I started with mine that way. I was unhappy with how my vacuum line plumbing turned out. It wasn't nearly as clean as yours. Plus, I have a tendancy to think, rethink and rethink things again.