I did PCV's on my 2 261 engines just recently. Used a PCV valve from a 75 250 6. Drilled a 3/4 inch hole in the valve cover,used a typical GM grommmet for the valve. I also welded in a sheet metal baffle under the PCV hole and stuffed it with copper steel wool like stuff to strain out the oil from getting sucked in.The one on the modified 261 blew oil out the breather over 4000 rpm, so I cut and welded up the stock draft tube, fitted a K&N as you see in the first photo.Uses a non vented cap on the oil fill, problem solved.The last photo is the reasonably stock 261, no problem with this , never revs that high. The PCV addition slightly leaned out the carb mixture slightly at normal speeds, ie,high vacuum when the valve is sucking.Not a problem on my trucks with Holleys may or may not be a driveability problem on another engine.
Side breather PCV valve More stock setup
