Pinto engines coming from a car with auto transmission have a different valve from those from manuals I seem to recall. Mine has an oil trap only in the crankcase breather, and no spring loaded valve as that impedes the gasses flowing out to the catch tank. When I bought my Westfield it had a breather from the crankcase and one from the cam cover which were combined before going to the catch tank. It would dump far too much oil into the catch tank so I looked into the problem. I talked to Vulcan Engineering about the need for a cam cover vent and the chap said there is no real need for one, and as the Burton article says, sprayed oil from the camshaft can find its way out via the breather.
Logically analysing the situation suggests a breather in the cam cover is not only not needed, but can be detrimental for both the above reason and another which I will come to. As others have said, an engine must breathe out any piston blow by that builds in the bottom half of the engine. There is no source of pressure in the cam cover so why vent it? Any puffing of crankcase gasses found when the oil filler cap is off have come up the oil return channels between the cam chamber and the crankcase and have not originated in the cam chamber. It might even be that a generous flow of these blow by gasses up the oil return channels could impede the oil's journey down to the sump. For that reason I removed the vent and sealed the vent holes in the oil filler cap. Once this is done, of course, the only path to the outside for crankcase pressure is through the crankcase vent and this MUST be of sufficient capacity to allow free passage of gasses and not offer any resistance or excess crankcase pressure will result. Having bunged up all exit points in the top half, I no longer need to drain the catch tank after a few hundred miles as I used to have to.
I know this is going against the conventional wisdom but the reason oil filler caps on 'normal' cars have vents in them is to allow air to be drawn in, not to allow gasses out. The positive ventilation system applies a low level vacuum to the crankcase via a connection to the inlet manifold, and the gasses are sucked into the engine and burned. Our modified engines do not do this.
Here's the OEM layout from a Granada with a Pinto engine:
The stubby barrel like item is the valve - get rid of that in favour of an oil trap froma manual car. I opened mine up and removed the spring loaded plunger and then reassembled it as a take-off elbow/oil trap only.