Don't shoot, I searched and I've been reading PCV threads here for hours... and even Googled for answers. I'm just finishing up a 350 for my wife's '48 Chevy peek-up and need some insight. The block is a 1985 350. I have a pair of Corvette finned valve covers that she loves, but I don't want to drill them for a PCV valve. I ordered an Edelbrock 2703 intake (Performer EPS and Oil Fill Tube, non-EGR). I've read that you can drill a PCV port in the back of the intake near the distributor but where? I understand it needs to be baffled, but how? I know what the inside of a baffled valve cover looks like, should I just do something similar to that out of sheet metal? How should I attach the baffle to the underside of the intake? Please don't say JB Weld... Am I trying to vent the valley? Because I'm thinking that the valley wouldn't share the same ventilation (at least directly) as the inside of the valve covers. Oil galleys don't pass through this direction, do they? Help a PCV-tard out please! Educate me. And give me some credit for not calling it PVC, LOL!
PCV - Positive crankcase ventillation. You are venting the crankcase so the valley would be fine. I don't know how much meat you have to drill into but tapping some blind holes on the underside and attaching a baffle with screws or bolts should work. I'd safety wire them or Loctite them as a minimum. Loose screws are not what you need in there.
I think he is talking about the outlet (PCV valve side)as an alternative to the valve covers, not the vacuum port.
The early 'Vettes had a threaded bung in the oil-fill tube, and used a threaded PCV valve. Still available through Ecklers, Etc. Here's an older thread with some info: PCV valve tech Or you could drill and tap the rear of the manifold for a PCV and use a breather on the oil fill tube.
If you properly prepare the metal,JB weld will hold a baffle --Heres mine,its on a valley pan,but same thing. Contact Dickster on HAMB he is very knowledgeable on the subject. The little silver fitting is the PCV valve----hardly noticable
There is a thread somewhere on this board with pictures.I hope this helps He even installed a baffle...
Just checked to the stuff I bookmarked Old relic did this thread.My pvc install in sbc intake ,Do a search Great pics......
From what I've read the baffles would keep direct droplets of oil from entering the valve itself. There's likely less oil being slung here than there would be in the valve cover or the crankcase, but from what I've read it's still necessary. Thanks for chiming in. I don't know the thickness yet either, as the 2703 hasn't arrived. I'd feel much better about drilling/tapping/Loctite'ing them too! And safety wire is a great idea! Yes, PCV, not vacuum. Thanks Gator. I talked to my machine shop guy about this earlier today. He said this wasn't the best idea, but I figured it worked for a LOT of Vettes and other cars from about '65 through about '69. I found another thread here that referenced Year One's site, so I looked there for ideas. I'm not sure why he doesn't like the idea, it doesn't seem any different (in my uneducated eyes) than tapping in to the back of the intake. Hence my inquisition here and hope for education! Thanks Gary. I have nothing against JB Weld, and like you said, if surfaces are prepared properly it will hold. The problem is not knowing if it DID without pulling the intake! Thanks for the pic, kind of what I was looking for. Is it just a ported into the valley? John, I've searched high and low for such a thread but didn't find it. Can you?
Looks like this is the thread you're talking about John, THANK YOU!!! http://www.jalopyjournal.com/forum/showthread.php?t=511505 .
Now, how much difference IS there between the pressure in the valve covers and the valley? I'd imagine it would quickly equal itself out with the oil galleys and room between the push rods, but is a valley PCV better/worse than one in the valve cover? I'd speculate that the valve cover is a better solution, which is why everything went this way... right? Or was it more emission related being late 60's early 70's when the change seemed to occur?
I think the concept of pcv was flow .To relieve crank case pressure .Its suppose to circulate from heads and valley .I think why they installed them where they did is location .Highest point, But pontiacs were in the valley..........
thanks for bring this thread up.. just got done reading the thread mention above: http://www.jalopyjournal.com/forum/showthread.php?t=525612 iv always thought the pcv was just a smog thing.. and really served no function other than to make EPA happy.. man, what a idiot i am. least im very opened minded about learning and have no problem being corrected. along there some substance to go along with it.... so maybe there is hope for me.. thanks again. chris.
If the 'IN' for fresh air is directly above that port, the intake vacuum is just pulling in that fresh air, and the acrid air remains in your crankcase...you have to flow that air from one end IN, to the other end OUT to properly evac the blowby gasses and whatnot. I don't have any personal experience with that exact part you posted, but to best work you would have to have a sealed fill cap above and a vented IN somewhere at the the opposite end of the block...
Early SBC were vented from the valley with the road draft tube which used a large baffel can in the valley. Mid 60s for a few years PCV was connected where the draft tbue had went. They all used a vented cap on the oil filler tube. Put the bloody PCV in the rear of the intake with some form of baffle and use a vented filler cap on the oil fill. Vented cap =one that has mouse fur or some other filter material in it.
Thanks again John, your help has been very appreciated! Good. I'm not the only one learning tonight! I knew what it was for, but I just didn't have enough understanding of the concept! Which screw-in PCV do you recommend? I understand that they're all made with different spring rates and flow rates. That makes PERFECT sense, thanks man! I'm understanding the PCV mystery a little more at a time. I'd read about that here, and there are a few recommendations for plugging that big road draft hole with a step to install a PCV. On another note oldrelics is helping me understand better through PM's. Thanks to everyone for your input!
I like to show this picture because it shows that even in the early 50s before the PCV system, they knew that there needs to be air flow through the engine. If you design your own system think about the air flow through the engine before you locate the breather and the PCV valve. To work well you want them as far apart as possible. You'll never see a PCV valve and a breather in the same valve cover. Figure out how you want the air to flow and then you can determine their locations. The factories spent a lot of money figuring it out. I like to follow their lead.
Tommy, while searching PCV here yesterday I read many of your posts but never came across this photo. This is great, thank you! I'd never considered the valve cover breather and PCV being on opposite sides, but you're right and it now makes perfect sense! Thanks for chiming in again on another PCV thread, I love this place and the amount of learning that can be done here! And the willingness of knowledgeable people to share! There are lots of bits and pieces of info regarding PCV here on the HAMB, but starting this thread has really brought a lot of those pieces into one place. At least for me!
First picture shows location of valve close to temp sender. I used a couple of 45 degree brass fittings to form an S in hopes that oil droplets would not find its way up and into the combustion area, but no luck. It would foul plugs in less than 100 miles. Has to have a baffle. Underside view of location. Welded in baffle plate. Works great with no plug fouling after two years use. Breather on oil filler tube is air inlet.
Awesome Dominick, thank you! This is the kind of info we can all use; where someone tried something, it didn't work, then they improved it and now all is well. Learning from others trial and error can sure save us a lot of headaches!
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