CK's TR6

Ah, my configuration is alloy cover, fairly large hose to air/oil separator, which has a PCV to an intake common plenum. Separator drains to the sump. Even so, without the plate, I still got oil coming out of the cap. The plate stopped that. Regardless, assuming the pressure inside the rocker cover is the same as the crankcase, you would need a lower absolute pressure in the intake at sufficient flow to overcome the total blow by such an amount that ambient pressure is higher than the resultant crankcase pressure to insure flow is into the engine from that breather hole. At wide open t

Flame trap? on an alloy cover?

I fabricated a piece of light gauge aluminum sheet that fit on top of two of the rocker cover hold down studs. It had a slight bend in it upwards to spring it against the cover. That provided a gap on each end for ventilation. Stopped the mist, weeping completely. Downside is I have to shove a flat blade screwdriver against it to add oil.

I have EFI with a Megasquirt 3X ecu. I obtained an old unused distributor body and modified it to 1. retain the cable drive for the tachometer and 2. provide a “cam” sensor for sequential injection. Essentially cut the weight pivot plate down to a single tooth and mounted a hall effect sensor on the side to detect the tooth. 3D printed a cap to keep any debris out of the body.