[Fot] Valvecover venting

[Ken Suhre]

Being a Chrysler Corp. technician for some 38 years, I
have a pretty good understanding of emission systems
on automobiles.

The positive crankcase ventilation (PCV) valve is what
controls the flow of engine crancase vapors to the
intake manifold. It has an orifaced check valve that
only allows flow when vacum is applied as the engine
is running. Air is drawn into the engine through a
filtered inlet in the aircleaner system, usually
through a hose to the opposite valve cover of a vee
type engine.

The charcoal canister is there only to recover fuel
vapors from the tank and carburator if it has one.
When the engine is running above an idle these vapors
are purged from the charcoal by the intake manifold
vacum. Usually through an orifaced port to control the
amount of flow.

Probably boring information to most vintage racers.
But I just had to try to clear up the confusion.

Ken Suhre
<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>




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