I have a 1993 331 stroker, EFI, water/meth injection, Vortech supercharger in a 1965 Mustang Fastback; brand new motor (500 RWHP). The hose coming from the valve cover comes down, through a hole in the front fender and next to my Air Filter (Air filter located in the fender well).
I always noticed drops of motor oil on the ground under the air filter. The oil is coming from this vent hose from valve cover. I was told that this vent vents pressure from the crank case when the engine is under BOOST, and that the vented air needs to be sucked back in the engine (why I don't know). So I jury rigged a plastic bottle over the end of the hose to catch the oil.
I was told to rig a "Catch can/bottle" under the car some how, rig this vent hose into the can, then another hose from the can to the airfilter. And install a petcock valve in the can/bottle to drain excess oil.
I've driven the car for 600 miles with MY jury rigged set up and no problems. I'm just wondering, is there a reason for this hose to be so close to the air filter, if it is simply a vent?