I have seen the Tech Tip where people have made modifications to the back of a stock style valve cover to add a port for a PCV valve on a SBC. That may work fine for some people, but I didn't want to modify an old stock cover if I don't have to. The originals are out there, but why mess them up if you don't have to. So I came up with a different method.
This will only work if you block still has the hole at the rear of the block for the Road Draft Tube and the hole in the intake manifold for the Oil Filler Tube. I have a '67 327 and it has both of these holes, but they are both blocked off with what looks like expansion plugs. Inside the lifter valley it will have a canister style baffle. (see photo RoadDraftHole.jpg)
Pull both expansion plugs and replace the front one with the Oil Filler Tube and breather cap. Make sure that it is a breather style with filter and no PVC port. (see photo OilFillTube_and_Breather.jpg) That's the easy part.
Since I am limited on the number of photos I can attach, I am placing the next set of photos in the message below this one.
The rear plug is a bit trickier and you will need access to some large drill bits or a small mill. Using the plug you removed from the Road Draft Tube hole, or a new one of the same size, drill/mill out a 15/16" hole in the center of it. (see photo RoadDraftPlug.jpg) My milling wasn't perfect, but will work for this.
Install a standard size PCV grommet in the hole (see photo PCV_Grommet.jpg) you just created into the plug. (see photo PCV_Grommet_Plug.jpg) you may need to trim the outside diameter of the grommet slightly.
This can now be installed into the Road Draft Tube hole at the back of the block. I don't have a photo for this yet since my block is still at the machine shop, but I have a photo of the completed assembly showing the PCV valve in the newly created port. (see photo PCV_Assembly.jpg)
After installing the assembly in the rear of the block, the PCV valve can be plumbed into the back of the carb, one of the vacuum ports on the intake manifold, or into the air cleaner. Your choice, as long as it has a vacuum source to run the PCV.
I don't know if this will help a lot of people or not. I'm not sure how many engines still had the road draft tube hole and oil filler tube holes plugged from the factory. It just seemed to be a cleaner way to do the installation. I am trying to make my '67 327 look as close to an old early model 283 as I can so that it doesn't scream "New Engine" in my '62 C10.
