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Re: Valve Cover Venting

Subject: Re: Valve Cover Venting
From: "Andrew B. Lundgren" <>
Date: Fri, 15 Nov 2002 13:20:18 -0700
Hmmm...  Wasn't clear enough.  A picture says... 

The picture is a few years old, but close enough.  The valve cover is a
non-vented AL cover.  The chrome cap had a tiny little vent on the top
though which the mist coated the cap.

The venting goes from the front cover of the tappet chest up to the
bottom of the weber with no PVC.

If I understood what you wrote, there is a back pressure wave that is
can somehow be created (that I didn't follow) from the carb back to the
tappet chest creating the need for the PCV valve.

Ruggiero Larry Lt Col AFRC/XPXS wrote:
> Hey Andrew...
> I'm not sure if putting a modern PCV valve into the valve cover tube would
> solve your specific problem. I've thought of inserting a "modern" PCV valve
> into the system, but only from the tappet cover vent tube. You didn't
> mention how your tappet covers are set up (breather on the front, rear, or
> perhaps not at all) but I see a potential problem in that the oil that does
> escape through the valve cover vent tube won't backflow into it because it's
> got a very small orifice hole. The valve cover tubes are set up that way
> because they're air inlets, not the venting outlets, and excessive inlet air
> is not desireable. If you optimize the tappet cover breathing portion of the
> venting loop, then theoretically all should be well. If your engine is worn
> enough to be producing excessive blow-by, then the misting will only get
> worse otherwise. Putting a "modern" PCV valve into the rubber hose between
> the valve cover tube and your carb tube  might contribute to more oil
> pooling in the hose, since it can't readily backflow into the valve cover.
> Larry
> Warner Robins, GA

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