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Thread: PCV routing

  1. #1
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    Mar 2002
    Austin, TX

    Question PCV routing high school auto shop was a long time ago...

    I had some work done on my '73 a couple of years ago. The major piece was the replacing of the flat tops with a couple of round top SUs. The mechanic also put on a pair of those "Ramflow" air filters in place of the original orange air box and filter. This was originally a CA car and so he also ripped all the emission stuff off...I could finally see the engine!

    Here's my question...I was under the hood the other day and noticed two things:
    1) The PCV hose that terminates into the top of the valve cover is just hangin' at the other end. I assume that it originally attached to the orange air filter box.
    2) Both the mounting plates for the ramflow filters have plastic tubes on their backsides that are open, not attached to anything.

    My concern is that dirty air is being sucked into both the valve cover and the air intake.

    comments/suggestions appreciated. Thanks

  2. #2
    Registered User hmsports's Avatar
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    Jan 2002
    St. Louis, MO

    Default hosed

    The valve cover tube was used to allow the hot gasses and oil vapors to get circulated back through the carbs, thus reburning and supposedly making things less polution prone. Simply replace the hose with a small air cleaner. K&N makes a valve cover breather, availabe from MSA for about $20.

    The other two were hooked up to the breather on top of the float bowl covers. This again was to burn any fuel vapors. Connect small hoses from the nipple on top of the float cover to the nipples on the back of the air cleaner housing.


    Rick Hanson
    HANSON Motorsports

  3. #3
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    Jan 2002
    Bornheim, Germany

    Default PCV

    Dstrong, instead of the PVC you may take a K&N filter (From MSA for instance) or you lead a hose to an additional reservoir underneath you coil or you lead a hose to a hole in the backside plate of one of your carbs. In that case you must be aware that this carb may become too rich.
    Is it possible that the plastic tubes should ber connected to the distributor's vacuum box ?
    Whatever it is, avoid unfiltered openings.


  4. #4
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    Jul 2001

    Default IIRC.. the tubes on the backs of the

    aircleaners are for fuel lines from the float-bowl covers, so that any overflow of raw gas and/or gas odors get into the carbs via the aircleaners - and not on to the exhaust manifolds.

    The hose off the top of the valve cover is your breather hose, it is supposed to dump into the stock aircleaner on the filtered side, so that the oily air gets sucked into the rear carb and re-burns.

    Also helps to reduce in-car stench and air pollution.

    The PCV valve on your vac balance tube should have a hose going down to the "nipple" or outlet coming out of the side of the block down below/right of the dizzy.

    Same bennies as with using your valve breather- stench and pollution reduction.

    (I have issues with the notion of dumping oily gasses into the vac balance tube... supposedly it should get sucked into the manifold, but I garuntee you it leaves a baked-on black film inside your balance tube. I just cleaned mine, and the carbon was flaking out by the ton. It pays to keep that PCV valve clean!)

    Another bennie with using both as intended is less oily air gets trapped under your hood - eventually crudding everything up.

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