I did a search but could not find the answer I'm looking for. Here is the set up. 350 SBC, 79 block. Edelbrock C-3B Manifold with oil fill provision. I have a set of M/T valve covers right now with a breather on the drivers, and a PCV in the p*** side. The oil fill hole on the manifold is plugged. I want to add a chrome oil fill tube with a breather, and run the PCV elsewhere so I can run a set of Un-cut valve covers. Can the PCV be mounted in the manifold at the front by the filler tube? There seems to be a threaded opening there that does not look to be in the fuel runner? Any other locations?
I have the same question.. Don't seem to be getting a straight answer.. I'm running the same intake with a filler tube with breather and old tin script valve covers.. Question is can I get by just with the intake breather? Do I need a pvc?? I'd really rather not drill the old intake or the valve covers..
Early pcv has a spigot from the oil fill tube (no vent at rear of crank case) to the carb and no breather in the covers.The pcv is inline between the spigot and carb......make sure you fit the arrow on the pcv going the right way.This system works very well and leaves no residue (white mess)inside valve covers.............Marq
i've added a PCV to a chevy intake by drilling a 1-1/4" hole in front of the coil mount/distributor area and installing a baffled grommet..i also added an aluminium baffle on the underside be carefull in doing so , you want to leave room for the coil ,and also not drill into the plenum
Marq, do you mean the PCV was in the filler tube or from a breather with a port on it and the PCV goe inline from that to the carb ?
I've seen the fill tube's with the provision for a pcv, although not too often. A buddy of mine has a 67 nova with a wicked little 350 in it. He wanted it to look like a stock 327, so he drilled a hole in the rear of the intake, like 36 3 window did. He then added a baffle to the underside as well. He's running stock 327 valve covers with no hole's now. It works great.
If you look at the old 62 corvette fill tubes they have a spigot that comes off them for the pcv tube,put the valve in-line with this and the carb using i think 3/8 hose......Marq
Thanks for the replies, I have a better ideaof what it takes. They also sell the breather/PCV that pushes into the oil fill tube, would that not be the same as the in line one. I see the oil fill tube with the bung for the in line PCV has a non vented cap, where would air come into the system? Or is it the venting out that you need? I could run a hose from the PCV on the breather to the carb, same as the one with the bung, but would you then need a air inlet into the crankcase?
Dooley i have both a vented cap and pcv take off.The fill tube i have is rarer but what i would do is get a normal fill tube drill hole for spigot and have a spigot machined with a nut for the back like mine then you can have both but this is what i already have and is original but i understand you cannot get them anymore as they are not made.............Marq
Are you talking about this one? Original Parts Group has them. You cant link directly to that item, only to their site. It's part # PPR1252. I just got one about a month ago.
Yes the PCV valve screws right in. If you use this tube and valve, Use the Corvette screw on oil fill cap that was made for it. You'll still need some kind of breather to let the air into the engine as far away from this tube as possible. If you use a vented breather on top of this tube all you do is **** outside air in to the PCV valve. This tube needs to be sealed at the top so that the PCV valve pulls air up through the tube removing the blowby and moisture that builds up down in the engine. For that to happen air has to come into the engine at a different location. The factory used a breather mounted in the side of the air cleaner connected to the p***. side valve cover usually. Check the mid 60's Corvette sites for the tube, cap, valve and probably the "correct" clamps for the hose. I think 62 was still a road draft system. In order to get bad air out of the engine...you need to let clean air in someplace else. otherwise you are just ****ing on a beer bottle. You still have to move your lips to let the air in or no beer comes out.
Does anybody know if a PCV actually improves your performance or hinders it, or if the difference is negligable? Right now I have two real purty Cal Custom finned valve covers with Moon breathers on them, and they look sweet, but the breathers spit a fog of oil all over the fenderwells. Also, I have to tape a funnel to the dipstick to add oil. totally ghetto! I'd love to add a tuble like the one above.
This is the worst subject for getting a straight answer. I have asked before here and other places and have yet to walk away with a clear answer. I am running a late model block, 3x2s, intake fill tube with a breather cap, and solid valve covers. Will this work, is anyone running this common setup and getting away with it? I understand the reasons for the PCV, but can I live without it?
Sedanman, I think that my Dad ran a 68 307 with no breathers in the covers and just a breather in the fill tube. I know there were no breathers in the valve covers, I cannot say for sure there wasn't a PCV somewhere. The breather was the snap on kind with the port on the side of it and believe it or not the port wasn't hooked to anything. The motor was kinda ****py to begin with so I don't know if it ran bad because of it, but I do not rmemeber any oil spraying out of that breather, or any other oil leaks... That's not to say it was the right thing. What would happen with just an oil fill tube breather for air?
Here's my straight forward answer. I have a sbc in my 33 pick up, running an Offy 3x2 intake and old Cal custom, no hole covers. I have a fill tube in the intake, and no pcv system. Will it work, yes, mine does. Would i recomend it, no.. here's why. For starters, there's a possibility of building crank case preasure under high rpm's.. My reasons, it makes a mess of everything. I have no hood, so the breather on the fill tube acts as a road draft tube and throw's oil all over the windshield and right side of the cowl when i'm on the highway..Just makes a mess. Plus when your stopped at alight, it smoke's out the breather like there's indian's in there sending off smoke signals! Now, i also have a 32 running a 283 with moon covers that does have a pcv system. Again, no hood and no oil what so ever anywhere. Granted, on my 283 i had a provision for the old road draft tube, so i made use of the breather under the intake and left it in there, then installed a soft plug, bored out to fit a pcv grommet in the old road draft hole. The pcv is hidden and works great. I understand that with a later block you don't have the spot for a 'draft tube, but a simple hole in the intake with a baffle under it will work. I've seen this done first hand.
Pack rat, Thanks for the answer. I am still undecided on what to do. I really don't want to bore a large hole in my manifold. It is an old offy 3x2 intake that I would like to hang onto in its orig**** state. Are there any other options? I am going to run just a top portion of the hood on my model A, will this help? If I did put a hole in the manifold where would I put it and where is it ideal to run the pcv hose to? I am running the Rochester 2G, do I run it there or run it to one of the air cleaners? I guess if I used one of the small screw in valves it wouldn't be that big of a hole.
This my solution that works great on my roadster. This was a mock up but you can see how it works. The inline PCV valve is plumbed from the base of the carb to the bottom of the old hot rod breather on this side. (I like these old breathers) The same idea as a PCV plugged into the top of the valve cover. This breather was blocked off above the PCV connection with epoxy. Air can't enter this breather anymore. The PCV pulls the vapors and moisture from the holes in valve cover under the breather. (like the chrome fill tube shown above, if this breather wasn't closed off, air would be pulled through this breather and no air would move through the engine.) The same breather on the p***. side was left alone to let fresh air in on that side.(I replaced the filter in the old breather) The same idea as the factory breather. You can see that the oil fill tube has a breather too to let fresh air in there too. I needed this tube for an oil fill so might as well add a breather. (the PCV valve isn't connected there) The air enters through the 2 open breathers. It travels down into the valley up into the right valve cover and ****ed out through the PCV valve to be burned in the engine. As it flows through the engine it pushes the fumes and vapors ahead of it just like a fan clears a smokey garage. Fresh air in... smoke out. For the fan to clear the garage you need to open a window on the other end of the garage to let air in. On a daily driver the cl***ic sign that the PCV system is not working is the chocolat milk shake **** inside the valve covers. That **** is moisture mixed with the oil. The PCV system removes moisture that can condense in your engine when it cools down if you don't get it out. That is what you have if you are just running breathers as pressure reliefs with no air flow through the engine. The engine will perform fine but it will get oily on the outside and gunky on the inside. A stock road draft system will work just as well. I run the stock 1951 road draft system on my flatty. The PCV system was a pollution upgrade. There all lots of ways to do it. Just remember that air must enter the engine somewhere else as far away as possible from where the PCV valve is ****ing out the vapors. The idea is to get air flowing through the engine removing vapors and moisture. Three after market breathers on top alone won't do that.
Tommy, Thanks for the help and the pictures. I work well from pictures. I have one more question as result of your picture. I am OK with getting a set of the side breathers for my valve covers and running a pcv system like what you have, but I currently have it set up with the modulator valve vac*** going to the center carb base. I don't beleive it would be right to run a line to one of the outer carbs for a vac*** source when running progressive linkage would it. Let me know what you think about this dilema. Tracy
My Carter 4bbl had a threaded hole at the base. I just put a barb fitting there and ran it straight into the valley cover (hole for draft tube) with a pcv there.
I emailed this question to the tech support at Edelbrock to see what they had to say. Their response was very similar to what PakRat32 said. You can run your motor with no PCV and just a breather in the oil fill tube. It will work but the chances of oil blow by and gasket failure/oil leaks are increased. I have some $$ in the motor and after consideration I do not want to sacrifice function for form. Besides you can't see the valve covers from the drivers seat anyway. It seems all Chevy small blocks had good air in, bad air out. 1st was the oil fill breather-Draft tube. Then they capped the breather for a PCV and had breathers in the covers. I am also thinking that with a vented cap and a PCV in the filler tube; like Tommy said, you would byp*** the crankcase and **** clean air into the carb/manifold vacuum. So what do you do? Run a filler tube with a vented cap, and a PCV eslewhere either in the valve cover, or intake manifold (exsposed to the oil galley) Or run a filler tube with either a bung, or threaded hole for a PCV line to the vac*** source. Or get a non vented cap with the bung on the side of it to a hose with an in line PCV to the vacuum source. And a breather or your choice on the valve covers. Or none of the above if you choose.
I just checked my 76 Malibu out side. The PCV is plugged into the intake just below the carb base. The modulator vac and heat/AC vacuum supply is picked up off the back of the intake in the central plenum. I wouldn't put them on the same port with the PCV. There is no air flow in the modulator tube or heater controls so they could be anywhere on the intake. All they do is pull on a diaphram that moves something. I'm guessing that the PCV should be near the carb base so that the idle mixture screws can be adjusted to compensate for the additional air that is introduced into the intake if you add a PCV. On my roadster I plugged it into the intake port designed for the brake booster fitting.(4 bbl) I had to reset the mixture but I've seen no ill effects. You don't want to plug the PCV into an individual port going to a cylinder like I did here. That would lean out that cylinder. Any other vacuum accessory wouldn't hurt that cylinder unless the diaphram ruptures. I'm going to relocate it to a pair of spacers under the carb bases. BTW my fancy breather is sealed and is only used as an oil fill cap.
That filler tube is a reproduction Corvette piece. That year used a screw on oil fill cap not a breather. You can use it with a cap and the screw in PCV valve but Like Chevrolet you will need to provide another place for the air to enter the engine to get the proper system function. How you do that is the interesting part.
Thanks guys.. glad to finally get a straight answer on this.. I'm running a junkie 79 sbc so F it.. I'll experiment without and see how it works... i'll be sure to post results..
Do you have a baffle plate on the inside of the dummy breather for the PCV? I noticed the hose sloped down to the dummy breather with the PCV positioned about midway. Seems like a good solution.
No baffle plate. The valve cover was drilled with a series of holes so they may serve as a baffle. I was concerned that the PCV might pick up a lot of oil splash from the valve cover but it seems to work fine. I was thinking of making a sheetmetal splash guard inside the valve cover but so far I don't think it's necessary. I think the slope is a good thing. most PCV valves are made to work in the vertical position. The vacuum has to work against gravity to open the valve. I have since found a horizontal PCV with hose barbs on each end. 1993ish?? Isuzu trooper II V6 pictured above with one hose barb sawed off for my application. It's spring loaded ugly plastic. I painted it to look better. I'm sure the engineers have a formula to calculate the best CFM for a particular engine. This one may not be a perfect match for a large V8 but it's got to be better than nothing at all. In this application (a flathead) I found a grommet that fit the body similar to what GM does only horizontally.
All of this discussion concerning PCV valves has got me to thinking-a most dangerous event for me. Anyway, I've wondered periodically about PCV valves and, specifically, is there a "correct" one to use? We all want our engines to look as clean as possible and go to great extents to make that happen. In order to do so, it may not always be possible to use the crankcase ventilation system that the factory used. So, my question is-how do you select the proper PCV valve? Is there, in fact, a perfect valve for the particular engine being used? Or, do you just select a valve that has the right esthetics and plumb it into your system? Are the valves specified for the cubic inches of the intended engine? I always kind of thought that any valve on any engine and that's that. However, I don't believe I have seen a truly definitive answer for this question, so I thought this might be the proper time to hop in and ask. Anyone know the real skinny?
Thank God I have never had a problem with a PCV, it seems to fluster a lot of people. All my engines have them and work fine, there must be a hundred threads on here about them
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