PCV - any pro's or con's

Engine, Transmission & Driveline

  1. ofb383

    ofb383 Member

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    Hey guy's, whats your opinions / thoughts on running with crank case evacuation - PCV against just having a breather on both valve covers and the port blocked off on the carb :confused:

    Are there pro's and con's ?
     
  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    For starters, what year car is this and was it set up with an OEM PCV system? The advantage is that the engine recycles any unburned combustion gases in the crankcase and keeps the birds, flowers trees and global warming nut jobs happy. There is an added benefit in that the oil life increases because the oil gets less contaminated by unburned gasoline. The only real disadvantage is that the PCV system uses throttle plate vacuum to operate, on an engine that did not have a PCV system to start with, usually some re-jetting of the carb might be necessary. On a tired engine with lots of blow by, oil can sometimes be forced into the PCV valve and the crankcase vent in the air cleaner causing the air cleaner element to get fouled with oil and the engine to smoke even more than it already does.

    On a stock engine, I would leave the PCV system intact. If this is on a high performance or race engine, the system is usually deleted.

    Dave
     
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  3. ofb383

    ofb383 Member

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    Hi Dave, it's on my 383, it did have pcv, now I have a aftermarket intake manifold and 4 barrel carb, bigger cam currently going in, I fitted the Mopar performance alloy valve covers but with just a breather on each bank. So leave it as or is the rear take off on the Holley suitable for PCV?
     
  4. Dana

    Dana Woodruff Carburetor Specialties FCBO Vendor

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    Yes, PCV all pros, no cons. There is a right one for every combo. But, a father and son team over in Pennsylvania ( dad a machinist, son an engineer) came up with a tunable PCV. And worth every penny. Check out ME Wagner. And do not deviate from their plan. Proper baffling is a must and the Mopar Performance baffling is terrible.
     
  5. ofb383

    ofb383 Member

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    I'll have look and see what they have to say on the matter
     
  6. Snotty

    Snotty Senior Member FCBO Gold Member

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    Keep it on.
     
  7. ofb383

    ofb383 Member

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    You say reinstate it?
     
  8. BigblueC

    BigblueC Senior Member

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    I agree with those above. Keep the PCV.

    :wideyed: No time yet to read anything, but that's a hell of a price for a PCV. It can't be THAT much better than a factory spec unit can it?
    upload_2020-1-9_14-28-25.png
     
  9. ofb383

    ofb383 Member

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    Think I'll stick with a basic factory style setup
     
  10. Dana

    Dana Woodruff Carburetor Specialties FCBO Vendor

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    the thing is factory pcv’s have springs tuned to every cars/engines respectable vacuum range.
     
  11. Dana

    Dana Woodruff Carburetor Specialties FCBO Vendor

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    Do a little reading, you just might learn something, I know I did. It is more than just a good pitch IMO.
     
  12. Snotty

    Snotty Senior Member FCBO Gold Member

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    Yes.
     
  13. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    First, here's what how the PCV works.
    http://www.hastingsfilter.com/Literature/TSB/94-2R1.pdf

    If you've ever taken apart a high mileage engine that never had a PCV, you'd know the answer. There's always a dark, nasty sludge that is the result of blow by contaminating the engine oil. That's one of the reasons why oil change intervals were much shorter, like 1000-2000 miles and engines didn't last near as long. I even used the retrofit kit that Chrysler offered to fit a PCV to a flathead Mopar engine.

    IMHO, leaving the PCV off any street engine is a mistake. There's nothing to be gained by doing so.
     
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  14. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    Most of the aftermarket carbs have a port for the PVC, it may be plugged but should still be there. Mopar performance covers generally have either a ported breather cap available to allow the running of a PCV. Or there is a rubber plug in the valve cover that can be removed to install the PCV. If your valve covers have a plug, be sure to install a solid cap on one of the breathers. Some of the race only valve covers do not have a provision for a PVC, so you will have to get creative or find a different set of valve covers.

    Dave
     
  15. CBODY67

    CBODY67 Senior Member

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    Years ago, I found an SAE Transaction on a GM study they did on crankcase ventilation, circa 1961, when road draft tubes were the exit point for crankcase vapors.

    There IS a particular flow rate for the valve. On the Chevy study, they used 1961 Biscayne 6-cyl cars in their plant security fleet (lots of low speed driving!!) for their test beds. In EACN case, the amount of condensate (which can make "acid" in the oil) was significantly decreased. Even more so with TWO valves. Internal engine cleanliness was significantly improved, without the condensate in the oil, clinging to the engines internal surfaces, worsening any sludge formation.

    On a dedicated race car, the normal pcv system is deleted, replaced by Pan Evacuation Systems, using two 1972-style Chrysler crankcase air intake "breathers with rubber hoses attached, which then connect to one-way valves in the header collectors. No flow restrictors, other than the resistance of the Chrysler-style breathers on each valve cover. Helps horsepower.

    As noted, the pcv system works with full manifold vacuum, usually via the primary throttle bores on a 4bbl carb. NOT just dumping into the intake manifold port. A Holley engineer mentioned that eh carb calibration compensates for the pcv flow.

    I believe the most generic pcv valves are basically small block Chevy valves. There was a "purple color code" pcv valve for the earlier '70s L82 350 V-8. A bit more flow with the wilder L82 cam, so this can be a tuning tool of sorts if the engine has a pretty healthy cam.

    With the pcv systems and the better motor oils of the middle '60s, engine life tended to increase by keeping the oil cleaner longer, which also aided in the longer oil change intervals which came later.

    End result, KEEP IT operational. It helps things be better, on may levels! Especially in cooler/colder weather!!

    CBODY67
     
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  16. ofb383

    ofb383 Member

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    This was going to be my next question, but you have mentioned it - manifold pressure for the PCV via the carb not manifold.
    I'll post a few carb photos later as I have another vacuum question for the take off to the dizzy and what take offs are ported and what are full manifold vacuum :confused:
     
  17. USSMOPAR

    USSMOPAR Member

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    The only con is not having a pcv as others have stated
    I wonder where these ideas come from......
    All these old boats and other old mopars should have an oil catch in the pcv line
    They work! Oil in the pcv line causes hi rpm detonation [pinging] that you can't hear but will show on the spark plugs. See mustang parts for an inexpensive one.Please don't whine like y'all like to do . The best "stock" pcv that has been found to work well is the 1990 360 4bbl truck pcv. All pcvs are not the same! It may be no longer available but they are out there