I am in the process of rebuilding my 425 engine for my 1965 Dynamic 88. The current PCV system uses the old style CV 639 flapper. I want to replace with a standard PCV system after the rebuild. I'd like to add the new PCV to the driver side valve cover. There is no hole in this valve cover currently. Does anyone know how I can get a Olds valve cover for the driver side of the 425 engine with a hole for a PCV valve?

connl, you can use any 260-455 valve cover. With a few exceptions for A-body big-blocks, all 64-later Olds engines use the same ones. 73-74 even had "OLDSMOBILE" stamped in them.

I think you can change out the rubber grommet in your existing valve cover and use the one for the later PCV valve. If the v/c has a D-shaped hole you can do this. If it has a round hole, you should be able to find something that will work and just use a Chevy PCV valve. Advance Auto has a whole rack of PCV grommets and valves.

You'll also need to install a breather. Factory put it in the driver side valve cover with PCV valve in passenger side, but since your d/s cover doesn't have the hole, you can get a Chevy style push-on oil fill cap that incorporates a breather element.