Larry Rominger wrote:
>
> I was getting the Tiger dusted off for spring and summer fun when I recalled a
> thread on this list addressing PCV connections and possible engine damage.
> Currently the valve cover with the PCV connection is attached to a vacuum port
> on the carb body. The other valve cover merely has an open cover and vents to
> the air. Does this side need to be connected to the air cleaner via vacuum
> hose or is my set up OK? This is on a 289, not a 260. Any assistance is
> welcomed.
>
> Larry Rominger
> B9473280
I think a lot depends on how often you drive, how dusty the area you drive in
is, and whether your engine has poor rings to begin with.
The vented filler cap makes yours an open PCV system, which was how the first
PCV systems were designed. Engine vapors sucked up by the PCV are replaced with
fresh air through a vented filler cap with some amount of wire mesh inside.
This air, if really dirty, can cause problems in your crankcase and eventually
the intake manifold and rings, because that's where it ends up going.
The open style cap of PCV system also is a vent for the crankcase vapors under
heavy load, when vacuum to the PCV is low. The blowby from the rings has to go
somewhere, and out the open filler cap is where they go. If your engine is in
good condition, you won't see much oil on the outside by the cap, but if your
engine is tired, you will get some residue on the valve cover.
This blowby residue is why the EPA mandated closed PCV systems in the late
60's. That is why cars since then have the tube going from the filler cap to
the air filter. In order to prevent the blowby from fouling the paper air
filter inside the closed housing on closed element air filters, there is a vent
filter inside the air filter housing. This also keeps some dirt from entering
the crankcase under normal high vacuum situations. Open element air filter
systems have the crankcase vent between the element and carb, so that the air is
filtered by the main air filter.
If you don't drive much, and drive in non-dusty areas, then the open system is
probably sufficient. If your air filter has a place to hook up a hose, and you
don't mind the looks of it, it makes for a better system to hook one up and make
it a closed system.
If you have to have your car smog-inspected, your state may require a closed PCV
system.
Gerard
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