I didn't start a thread on it, but I mentioned it in a few replies over in the rcg engines forum.

The so called PCV valve is in fact just a sprung loaded one way check valve allowing a small volume of air drawn in and then closes on the down stroke of the piston... the crankcase breather / blowby gasses get forced up the push rod tubes through a small passage cut in the cam follower bushings, and then down a small orfice in the intake runner under the rocker cover, just behind the backside of the intake valve... the orfice is too small for much of a scavenging effect, but small enough not to allow a large volume of gasses to be forced through that small orfice... so pressure builds in the crankcase in the lo / mid throttle range... the fuel pump pulse pressure port is in the backplate just above the PCV check valve, it's visible externally as a short piece of transparent tubing connected to the fuel pump pulse inlet nipple in the carb.

I ended up removing the rocker cover and blocking that orfice with a small allen set screw ( drilling / tapping )... and then adding a large threaded nipple in the rocker cover to vent the crankcase blowby and lubricate the valve stems / rocker assembles... you can remove the ball and spring from the pcv check valve, but I choose to leave them in place, as the vent nipple I put in the rocker cover was large enough to vent the crankcase efficiently... I made a threaded nipple from some brass round stock with a 3/32" ID... worked a treat, the engine ran much more consistant and got rid of the burble through the lo / mid throttle transition.

In the GF40 pdf manual, there is a drawing showing how the PCV system works.