PCV vs. Breather.....

[WadmalawJoe]

Originally Posted by bk2life

so i guess your old know it all neighbor is a bit wiser than you think....

Somebody gets to eat crow......

[jaros44sr]

Originally Posted by fastcam1

So I have a set of Chevy script valve covers, what do I have to do so I don't have to drill holes in them?
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Good question. Youd have to find the baffle, then the block has to have a knock out in the proper location. Newer blocks dont have it. Intake has to have the tube in front for air in

[fastcam1]

Originally Posted by jaros44sr

Good question. Youd have to find the baffle, then the block has to have a knock out in the proper location. Newer blocks dont have it. Intake has to have the tube in front for air in

Ok the block I'm using is a 76. Is there a way to tap into the rear of the intake manifold and install a valve there?
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[jaros44sr]

Originally Posted by fastcam1

Ok the block I'm using is a 76. Is there a way to tap into the rear of the intake manifold and install a valve there?
Posted via Mobile Device

Its not quite that simple, if you do that, there would be oil getting sucked up the pcv line along with gases. So, you need a baffle to stop that from happening. You only want to evacuate the vapors. I had read that there is a dead area between the distrib. and carb. in the lifter valley, but im not positive of that.

You still need filtered air in to the crankcase, since the pcv is sucking it out

[orange 69]

Originally Posted by jaros44sr

Its not quite that simple, if you do that, there would be oil getting sucked up the pcv line along with gases. So, you need a baffle to stop that from happening. You only want to evacuate the vapors. I had read that there is a dead area between the distrib. and carb. in the lifter valley, but im not positive of that.

You still need filtered air in to the crankcase, since the pcv is sucking it out

Does anyone have pics showing how to run this style system? I have a 1973 400SB with the oil fill in front of intake and want to run the script valve covers as well.

[GASoline71]

A lot of cats using the old closed style covers will drill a hole in the back of the cover that faces the firewall to get a PCV system hooked up..

Unless you have an old block with provisions for a road draft tube. You WILL have to drill holes in the old style covers to make them work properly on a newer block.

Gary

[jkeating1]

Originally Posted by orange 69

Does anyone have pics showing how to run this style system? I have a 1973 400SB with the oil fill in front of intake and want to run the script valve covers as well.

I have yet to see pics of one, but my 67 283 has a PCV valve with the in-to-carb-base end threaded, and the other end with a 1/2" hose barb for the hose from the crancase. It should have had a hole in the block directly behind the distributor, but a PO put a later block in. It came to me with later valve covers with holes in them. I plan to put an NPT threaded port just in front of the distributor and baffle it some way. Of course, it will have to retain the filtered oil cap on top of the oil fill tube in front of the radiator hose neck. I understand there are two types of screw-in pcv valves---one screws into the crankcase air-outlet hole. The other is like mine and screws into the vacuum source (carb base plate). That would mean they are designed to flow opposite of each other, so you would have to be sure you have the right one for how you are using it. Mine has an arrow stamped into it. I just went to AutoZone and asked for a PCV valve for a 67 C10 with a 283, and thats what they handed me. I have seen both types in Classic Industries catalog. Go to the catalog on their site and search PCV for various 62-67 models (impalas, Novas, etc) and you will see the "road draft" style vent tubes, as well as the tube for a closed system. I think the Nova catalog shows that. But remember, for any one of those, it would have to be a block with the provision for that end of the ventilation system. BTW--someone please correct any part of this, so I can get mine right too!

[jaros44sr]

Originally Posted by orange 69

Does anyone have pics showing how to run this style system? I have a 1973 400SB with the oil fill in front of intake and want to run the script valve covers as well.

Isaw a guy on here that was real creative with a block of aluminum, mounted on the back of the vc as gary said. Cant remember which section it was in....might have been the engine section. Someone else might know of it, it was pretty slick, and not difficult to make

[jkeating1]

This is how it was on vehicles with no holes in the valve cover, and a closed PCV system. The first pic is the PCV valve on a 67 C10, the second is the fitting in the back of the block for the other end of the hose. The third and fourth pics are of the same setup, but on a 67 327 Camaro block. Not shown, but absolutely necessary, is the oil fill tube pressed into the front of the intake with a filtered oil cap. (that is, if you arent going to have breathers in the valve covers. Besides having to let air into the crankcase, you'd have to be able to put oil in somewhere anyway)

[jkeating1]

Originally Posted by Longhorn Man

I guess I should have clerified and described/explained the whole system again when I said it is benificial to install. The needing both was implied. A PCV with no breather/air filter tube will do nothing except probably suck the intake and/or valve cover gaskets into the engine.

cparman, let your buddies raz you all they want. You have the correct set up.
jonnybravo, the only way you can do this and have it work properly, would be 2 PCV valves on one valve cover, and breather/tube to air cleaner on the other. If you just go valve on one side, and valve on the other side with no way to get air in, you will suck the gaskets into the engine.

When I read this, I chuckled thinking you were kidding about sucking the gaskets into the engine. Then I remembered that, when I was replacing the VC gaskets on mine, the long, straight sections of the gasket between the bolts was drooping on the top, and not seated along the bottom. I never put two and two together, but I did replace the oil fill cap because it was caked with oily, greasy, dirt and likely not venting at all. Thinking back, I guess it was trying to suck the VC gaskets into the engine!

[geezer#99]

Originally Posted by jaros44sr

Isaw a guy on here that was real creative with a block of aluminum, mounted on the back of the vc as gary said. Cant remember which section it was in....might have been the engine section. Someone else might know of it, it was pretty slick, and not difficult to make

Here you go!!
http://67-72chevytrucks.com/vboard/s...d.php?t=366853