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RE: Emission Stuff

To: Triumph List <triumphs@autox.team.net>
Subject: RE: Emission Stuff
From: Randall Young <ryoung@NAVCOMTECH.COM>
Date: Fri, 5 Oct 2001 18:37:57 -0700
Jim :

Yes, that's exactly the type of system I was talking about.  As someone
already posted, the PCV valve actually allows a slight vacuum to be drawn on
the crankcase, when there is manifold vacuum (eg idle or cruise).  However
at wide open throttle (no manifold vacuum), it allows pressure to build up
in the crankcase, which can blow oil past all the troublesome seals,
especially the valve cover gasket and the rear main seal.  The other problem
is that it promotes acid and varnish formation in the crankcase, because it
is always filled with blowby fumes, there is never any fresh air added.

Probably better than removing the PCV valve would be adding a fresh air
intake line, with a fairly large-bore tube routed from the other end of the
valve cover (or the hole for the road draft tube if it's still there), to
the air cleaner housing.  Thus, when there is manifold vacuum, fresh clean
air will be drawn through the crankcase.  And, when there is no manifold
vacuum, any blowby will flow out the added tube and be sucked into the
intake and burned.

But if you are having trouble with oil leaks, it's certainly worth trying
just disconnecting the valve and running a tube (heater hose works for
awhile) down towards the ground.

Randall

Jim Muller wrote :

> Does this evaluation enclude the "flat-disk" PCV valve on a '70 GT6?  It
> seems to be just a "one-way" valve.  I don't know for sure (yet) but it
> seems like it would release valve cover gases to the manifold
> only when the
> pressure inside the valve is some amount greater than atmospheric.  There
> seems to be no other crankcase venting.  Are you suggesting just
> pulling the
> valve off and installing a tube to vent gases under the car or some
> similarly innocuous place?

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