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> 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
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