[Fot] Valve cover breather

[Steven Preiss]

Do you mean "...exhaust venturi scavenging positive pressure from engine
crankcase, and rocker cover venting via the vent on the catch can?"
I always thought the crank case and valve cover vents acted in tandem to
allow the engine to breathe in both directions. If a vacuum is applied to
both, wouldn't that cause a vapor lock? I also thought that the crank case
breather tube was designed to draw out the "vapor" when the vehicle was
moving, with increased vacuum at speed. I believe that when a closed system
was required by emmission control regulations, the pop-off valve was
employed to direct venting to the intake manifold when the vehicle is
stationary, and to the carbon canister when the vehicle is in motion. Please
correct me if I am wrong. (Was replacement of the carbon canister a part of
scheduled maintenance?)

Steve P
----- Original Message ----- 
From: "Peter Vucinic" <pvucinic at netspace.net.au>
To: "'Tony Drews'" <tony at tonydrews.com>; "'William G Rosenbach'"
<wgrosenbach at juno.com>
Cc: <fot at autox.team.net>
Sent: Sunday, December 30, 2007 1:38 PM
Subject: Re: [Fot] Valve cover breather


> I did this with my TR4 and have the exhaust system venturi system
scavenging
> positive pressure from the engine crankcase and rocker cover, via the
upper
> portion of the catch can. Works a treat.
>
> Peter V
> TR-4
>
>
>
> -----Original Message-----
> From: fot-bounces+pvucinic=netspace.net.au at autox.team.net
> [mailto:fot-bounces+pvucinic=netspace.net.au at autox.team.net] On Behalf Of
> Tony Drews
> Sent: Sunday, 30 December 2007 6:26 AM
> To: William G Rosenbach
> Cc: fot at autox.team.net
> Subject: Re: [Fot] Valve cover breather
>
> Works, but doesn't pass tech as vent lines need to go to a catch tank.
>
> - Tony
>
> At 01:08 PM 12/29/2007, William G Rosenbach wrote:
> >What ever happened to the practice of creating a Venturi at the outlet of
> >the exhaust header and feeding the crankcase vent line to it, to draw
> >crankcase gasses out?
> >Used to see that a lot on V-8s @ the drag races
> >Bill
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