Plugging the valve cover, and putting a many breather on the end of the tube, but my oil cap has a breather cap, so I wonder if thats good enough. If thats good enough I want to block both ends. I know the crank case needs to let pressure out, through this. I know there is really no solid gain doing this. Only, no oil will trace back up the return and back into the intake manifold, with is good enough for me. Plus, less heat in the intake, due to coming out of that area. Leaving the combustion a bit cleaner, and cooler. For a longer living engine. I also had a trick idea putting duel oil valve covers on both sides of my block. Winsor and Romeo blocks have opposite side oil fill valve covers. I think it would look trick to get one for my passenger side, and put a breather cap on it too.