Wanting to hear actual experience of you who have installed a PCV valve in your intake manifold, without any baffle underneath the PCV valve. I have a correct size valve ready to screw into a 1/4" tap between carb and distributor, in an Edelbrock Performer RPM manifold on 406 ci street driven SBC. The manifold has anoil filler neck in front with a large vented cap on it. Will attach the PCV valve with a 30 degree elbow, 1/4 npt male down by 1/4 npt female up, to clear distributor. Manifold is already on an installed engine. My concern is will the PCV valve suck too much oil from that particular location? The research I have done has mixed results. Also, any tricks for adding even a minimal baffle on bottom of elbow" I have seen a short metal tube with some small saw cuts on it pinned and JB welded to bottom of elbow. TIA!
It will probably draw in some oil at that location, but I'd try it and see what happens. It is close to the setup the road draft tube used. They used a big oil separator on the road draft tube. Early PCV conversions put the PCV valve in a cap that replaced the road draft tube. My 57 T-Bird is set up that way. The best way to build a baffle is to remove the intake and make a sheet metal baffle. You can drill and tap the manifold for small machine screws to hold it in place on the bottom side of the manifold. With that said, you won't really have an efficient PCV system with that setup. It will draw air in from your filler cap and not properly vent the crankcase. The way you should set it up is to block the oil fill tube, put a vented cap on one valve cover and the PCV valve in the opposite cover. You will definitely need a baffle below the PCV valve on the valve cover setup.
I’ve personally seen a lot of engines use excessive oil with the pcv installed in aftermarket valve covers with no baffles. Install baffling and oil consumption stops. I would imagine there’s as much oil vapor in the valley and you would have a problem. I also agree that the breather up front in the intake would not give the ventilation you want. I’ve used the rubber pcv grommet with a built in baffling with good results but there meant for valve covers and need a 1-1/4” hole.
I did the setup jaracer mentioned. I also have a fill tube in the intake. I put a rubber expandable freeze plug in it and attached the vent cap to the rubber plug so it doesn’t look any different. Breather on left valve cover and pcv in the right valve cover. I guess it works OK. I did it in an attempt to fix a rear main leak but it appears to still be leaking.
I did the same on a performer intake. I made a sheetmetal baffle that fit under the V formed by the rear intake runners. Without the baffle you can loose 3 quarts of oil in one hundred miles.
I tried it on my coupe so I could run my Corvette valve covers(no holes). Drilled and tapped a hole behind the carb, Even added a length of tube w/small holes drilled in it. Smoked like a train. Had to go with different valve covers, works fine now.
I’ve got the corvette covers myself and didn’t want to drill them either. I put the pcv in the road draft tube location and used the fill tube breather for air. It did smoke a little but nowhere near 3 qts. to a hundred miles. I didn’t want to take the 3 Rochester manifold off and had no luck with the little rubber baffle in the draft tube hole. I ended up taking an old glass fuel bowl, removed the element and installed a tube on the “In” side of the housing (so the oil would settle at the bottom and not get sucked out the other side) and the “out” side just gets air. I can go a bunch of miles before it needs dumping. Yeah I know, it’s the long way around but I was bored and it works great. I did have a 327 that sucked a bunch of oil, I mean a bunch and I changed valve covers on that one. My little oil separator would of been over come in a short drive.
My brother has this set up on his truck. He hasn't reported any problems after many years of driving. I suggest a sheet metal baffle attached under the hole in the intake. Stuff in some stainless steel pot scrubber material to help catch the oil. Or you might could fab a baffle like an Olds or Pontiac that covers the opening under the intake. This would keep the oil droplets in check.
If needed you can add a “catch can” in the line. This is common with new cars with port or chamber FI. It keeps oil vapor from coating the inside of the newer car intakes since the PCV line is just behind the throttle butterfly. Many are offered on the net. Ford has them for “off road” Mustang 5.0. When crankcase fumes enter under a carb and mix immediately with the gasoline vapor it’s no big deal. A test of any system is whether it will hold a piece of paper on the vent. A correct test is with a vacuum gauge where 1 to 3” of vacuum is correct. I check it thru the dipstick hole with the intake air vent sealed. Here a photo of intake vent holding paper on my running engine. You can see the hose from the oil filler. My rockers don’t have any holes.
I've never done the pcv in the intake thing yet but have plenty of experience with a pcv in a set of cheap aftermarket valve covers with no baffles keeping the inside of the cylinders well lubricated. Those things are still out in the shed waiting for some 8 year old who wants to make a shiny valve cover race car.
I have an early sbc intake that I retrofitted a pcv. Created a simple sheet metal baffle below the pcv and it draws no oil. Easy enough to fab with intake off, why chance it.
As stated above, a hole in the area behind the carb and in front of the distributor is a perfect place to drill a hole for a PCV grommet in an air gap manifold. On the under side of the manifold in that area bend a 4 sided metal box about 3/4” thick closed on 3 sides with a small lip on the rear side turned up. No welding necessary because you want it to drain. Drill 1/8” holes in the corners and screw or rivet it to the bottom of the manifold. Many engines with metal valley covers were stock this way starting in 1961. The Ford Y-Block for sure and many have done this. The only problem is getting the newer intake drilled for the oil fill tube. A good machine shop can do this.
Take a few minutes and read some of the technical information on this page: http://mewagner.com/ The valves are not inexpensive but they work especially on a modified engine. I am using one on the Boss engine, plumbed it in the left valve cover (baffled) and used a sealed cap with a breather tube on the right valve cover, the breather tube goes into the base of the air cleaner inside the perimeter of the element so it draws filtered air into the engine. I also installed a small oil separator between the valve and carburetor, although I do not feel it was necessary.
Why not just get the proper (Corvette) oil fill tube that takes a screw in pcv and leave the intake alone, that way you don't have to drill a hole and make baffles. https://www.classicindustries.com/p...XwijXTwArQD2uodqntjjYem8NtJR72y0aAlijEALw_wcB
This might be of some help, Ford uses this screen which sits in a baffle in the rear of the intake and is held in by the PCV grommet. https://www.cjponyparts.com/ford-pc...NclhpCi4bwTuPOjToknvx6L1Mram1HpgaAgExEALw_wcB
I plan on using this system on my small block. I have a small baffle that will fasten below the hole in the intake with machine screws and safety wire. I also have a lifter valley windage tray to keep oil spray down. Keep your fingers crossed!!
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