== fot at autox.team.net supported in part by Fat Chance Garage
== http://fatchancegarage.com
In a message dated 11/20/2005 10:38:56 AM Pacific Standard Time,
owner-fot-digest@autox.team.net writes:
> ate: Sat, 19 Nov 2005 10:05:57 -0800
> From: "Randall" <ryoung@navcomtech.com>
> Subject: RE: Re: catch cans
>
> == fot at autox.team.net supported in part by Fat Chance Garage
> == http://fatchancegarage.com
>
> > but consider installing
> > a PCV valve between the rocker cover pipe and the intake manifold. The
> > flat factory model works just fine, and will give enough vacuum to
> > keep the crankcase pressure down while recirculating those smelly
> > fumes.
>
> I've not seen anyone else mention this ... at full throttle there is no
> manifold
> vacuum, hence little or no flow through the PCV valve but blowby is at
> maximum.
> To avoid blowing oil past the seals and rocker cover during WOT, especially
> on
> an engine worn enough to have much blowby, you need a large open vent. The
> factory overlooked this, which IMO is part of the reason all Triumphs leak
> oil.
>
> The American system of providing a rather large diameter "fresh air intake"
> between the crankcase and the carb air intake (in addition to the PCV valve
> to
> the intake manifold) is better, IMO. It allows fumes to flow "backwards"
> into
> the air intake during WOT operation. It also promotes a flow of fresh air
> through the crankcase under other conditions, so that blowby fumes have less
> of
> a chance to condense and form acid when the engine is shut down. This line
> is
> the place to put a catch can if you use one, since WOT is usually when the
> blowby volume/velocity is enough to carry oil droplets.
>
> It's also possible to have the crankcase fresh air intake separate from the
> carb
> intake, but then it needs it's own filter so that dirt is not carried in
> during
> cruise (high vacuum) operation.
>
> Randall
Thanks Randall, good points all.
As you say, not mentioned by anyone else here, yet...
I have several ideas to try, but the main problem is that I have Weber
40DCOEs with K&N's and the intake manifolds on the Webers are the seperate GT6
type
with no balance tube between them. It is apparently, not advisable to take any
vacuum from just one, or two, cylinders instead of from some kind of balance
tube, at least according to what I have been reading.
The catch can is also supposed to be fitted at the same height, or higher,
than the valve cover, which is fairly difficult if not impossible on our six
cylinder engines.
I am in the planning stage, and will be trying out several configurations
next Spring to see what works best.
Thanks again
Lion
63 Vitesse (MK.2: 1971 engine), 1998cc, Triple Webers 40DCOE, Triumph Tune
GT6 intakes, K&Ns etc.
Please see photos at:
<A
HREF="http://community.webshots.com/user/vitesse1963";>http://community.websho
ts.com/user/vitesse1963</A>
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