I've got a '74 2.0L D-Jet motor in my car. The PCV valve has nothing inside of it (no spring or valve) so it's basically a port on the oil filler. I've got it hooked up to the airbox, like L-Jet. I can't hook it to it's stock location on the plenum as it'll over-rev the motor at idle.

I've noticed that there is oil on the inside of the plenum, presumable from the oil fumes coming through the PCV valve.

Is the arrangement I have ok, or should I try and find a PCV valve. Do I risk fouling the plugs? The car does not smoke.

I will answer the question with a question.

What does PCV stand for?

Rich

Some 914s had an actual PCV valve, others didn't. I don't recall which years/engines, but I know my 2.0 did not have one. It did however have a hose that connected at the base of the oil filler... So Vent yes, valve no.

Positive Crankcase Ventilation. This article seems to indicate that the PCV valve was eliminated in the '75 D-Jet motors.

yes it was...and they did away with the head venting too. Different setups totally.
If you have the early setup use a PCV valve or install a plastic ball with a 4mm hole drilled init to meter the air pulled into the plenum..The crankcase must be vented or the blowby pressure will blow out the seals.

IF you have VENTED heads you will need the PCV valve.

I am a wise ass sometimes.

Its a vent for the case pressure.
So, it has to get vented...that is a fact. If you dont relieve that pressure, it will find another way out...typically seals will blow, in severe cases you could see an oil galley blow out.
The original school of thought was a simple venting to the atmosphere...ooooo not good.
The second step (and all cars have this) is to re-burn the vented gases.

In a drag motor or race motor, I would vent to the atmosphere to keep my air/fuel mixture exact.
In the real world, we re-burn these gases.
It has to go into the intake track somewhere, so where you have it works.

RIch

My head are vented. Yes I know I need to vent the crankcase. It is currently vented straight to the airbox with a 12mm vacuum line. I will try and source one.

Rich, you're a wiseass sometimes???

It works the way you have it just fine.
One my 1.7 its routed to the plenum.
On the 2.0 liter its routed to the air cleaner box, not the plenum

Rich