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PCV desperation!

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ccowx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Topic: PCV desperation!
    Posted: Sep/15/2020 at 10:20am
I am hoping for a quick answer on something. I have a persistent issue with my PCV sucking oil. In desperation I am planning to stuff some foam rubber to act as a filter in the air chamber under the PCV valve. I will be doing it in the next couple of hours, unless someone has a better idea! Where i live, summer road test season is short and closing rapidly!

Here is the basics of the set up:

-R4B with baffle/heat shield
-Group 19 cam and Holley 780
-Full metal pan intake gasket
-PCV valve in place, tried both stock and a modified one to work with lower vacuum. 
-No blowby to speak of, no ring seal issues, definitely oil in the PCV valve. None in the hose from filler cap to air cleaner. 

I am looking to see if having a foam filter will separate the oil out of the air that is being sucked into the PCV.

Thoughts? This has been a persistent issue for years with this engine. 

Thanks!

Chris 
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390amx1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 390amx1 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 10:38am
I have nearly the same setup as you do.  My PCV was also sucking oil.  Somewhere in this forum someone mentioned just because the PCV fits doesn't mean its correct to the engine and each PCV has a different orifice (maybe BillD).  In the same thread the member stated  the correct part number that worked for him.  I simply changed my PVC to that part number and it worked!  I couldn't believe it.  Maybe this will work for you. My original PCV valves were chrome and I used many trying to fix the problem.  The correct one that worked for me is black.

Edited by 390amx1 - Sep/15/2020 at 10:40am
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ccowx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 11:43am
I wonder if that thread might be one that I was part of a year or two back. I do have the correct black metal PCV valve in place. I also looked at the chart in the TSM that gives flow rates for that valve at certain vacuum readings and determined that my cam, with it's lower than factory vacuum properties, was probably flowing too much at a steady cruise. I took a stock PCV valve apart and modified it internally to hopefully work better with the different vacuum settings. I lightened the plunger and also shaved down the spring a bit. No difference.

Is there any worry about having a foam filter in the PCV chamber under the valve? I wonder if it will help separate the oil and air or if it will create a pool that helps "wick" the oil up the PCV valve?

Thanks!

Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 390amx1 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 12:04pm
I'm not a big fan of "catch cans" normally but did you consider that as an option?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 12:18pm
I considered putting a fuel filter inline with the PCV valve as a temporary measure to see if that helps. I would prefer to not have any obviously non-factory or period correct items on the car.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 12:32pm
I'm still running the orifice PCV valve mentioned in this thread and oil usage is 1/2 cup in 2000 miles now:
No moving parts, just a little can with a hole. Not much can go wrong with it.

I had a buddy that put in a new PCV valve from NAPA, correct for an AMC 360. On inspection it was jamming open. I compared it to an original and instead of a taper on the ID it had a pronounced ridge that the "plunger" got stuck on. I just put in the old original one I had and all was good.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Midnight Rambler Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 1:18pm
If you aren't sure what brand valve you are using, try one of these:

# FV164   = FRAM
# FV164DP = FRAM {#FV164}
# V164    = STANDARD MOTOR PRODUCTS
# 6P1011  = AIRTEX

PHAT69AMX provided the list some time ago.  I had a blowby issue that was resolved by changing to the V164.


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ccowx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 3:50pm
I have considered a fixed orifice valve. I also have found the thread that you are referencing with all the part numbers. I might try either method.

I think I will order the V164 from Rock auto. That seems to be the one that works, according to the older thread. I have been using the Borg Warner version and it does not seem to work. If not, then next up is the fixed orifice unit.

Thanks!

Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 5:37pm
When you get the V164 or FV164 (they are the black oxide ones), hold it horizontally and tip it to vertical several times. If the plunger always falls you should be good to go. If the plunger holds up about 1/8" then toss it.
That's the one buddy had and it was machined with a square ledge on the ID that intermittently held the "plunger" open.
I believe they are all made by the same manufacturer and there may have been a mistake/flaw/cheaper process in manufacturing these.
If there is a ledge you can see it with a small flashlight also. Originals had a taper.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Sep/15/2020 at 6:32pm
I would't use foam as it might break down when laden with oil. I packed the smaller cavity on my air gap with one of those stainless steel pot scourer pads to try to block some of the oil.


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