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RE: Valve Cover Venting

To: "'Andrew B. Lundgren'" <>,
Subject: RE: Valve Cover Venting
From: "Dodd, Kelvin" <>
Date: Fri, 15 Nov 2002 08:10:23 -0800
Seconding Larry's comment.

To do any good you want the vented front tappet cover.  Run the PCV valve
from that cover to the Inlet manifold.

The sizing of the PCV should not be highly critical so long as the vent on
the rocker cover is sized appropriately.

The black vented cap has a pretty small hole, so it should be ok, but only
experience is going to tell.

It's important that what ever PCV valve you install is plumbed in the
correct direction, and can handle the amount of gases blowing by the rings.

I suggested installing a PCV valve to some guy out in CT and received a very
harsh letter when the car puked more oil out of the seals than before.  I'm
guessing he had the valve installed backwards, and with the now sealed
engine all heck broke loose.  So make sure there is adequate suction, but
not so much as to lean the mixture out under load.  To do the job right, I'd
suggest putting a sealed oil filler cap on the valve cover, then drilling
and tapping the cover for a vent that can have an orifice installed.  A
little K&N filter on the end of the vent is a nice finishing touch, tho'
I've seen fuel filters used as a cheap alternative.

On the car I'm building, I'm using the later HS4 carbs which have the ports
for the crankcase vent.  With a sizable orifice as per above, the system
should work ok (i hope).

Lots of fun.


> -----Original Message-----
> From: Andrew B. Lundgren []
> Sent: Thursday, November 14, 2002 7:16 PM
> To: Ruggiero Larry Lt Col AFRC/XPXS
> Cc:
> Subject: Re: Valve Cover Venting
> Thanks for all the great info.  I have a the vent from the 
> tappet chest
> cover piped up to the intake on my weber with no pvc valve.  I have
> been trying to figure out why I get oil all over the top of 
> my aluminum
> valve cover.
> I had to switch from the chrome oil cap to the old black vented one
> because of the oil mist all over the chrome cap made it so slippery it
> was almost impossible to remove the cap.
> I will buy a PVC valve and hope to see the problem go away! 
> Is there any sizing to these things or just get one that fits the
> hoses?
> On Thu, 14 Nov 2002 14:26:06 -0500, Ruggiero Larry Lt Col AFRC/XPXS
> wrote:
> >then the reverse pressure wave
> >goes right back into the crankcase, pressurizes it, and 
> forces oil out where
> >it's not supposed to go, like the oil cap/valve cover tube, 
> crank seals,
> >dipstick, oil pan, etc.  Not good.

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