[rsk289]

I've just checked out a C7ZE PCV I have, and it is indeed 1/4 NPT (18tpi). So the requirement is for a brass elbow to thread on to the top of the PCV (1/4 NPT), with a hose barb for 1/2" ID hose.
I have found some NOS brass 90° elbows of the correct shape on ebay, which have the 1/2" hose barb with a single lip, but have 1/4 NPT male thread. I am going to cut off the thread, then drill and tap for 1/4 NPTF. I will post a picture once done - but it may be a while as ebay's ridiculous global shipping centre was requiring me to pay $370 to ship 4 brass elbows! I've had to get them shipped to a friend in the US who will post them on to me.

All good fun,

Roger

BTW, BSP is British Standard Pipe thread - I can't see Ford using that back in the sixties. It's surprising what weird older threads do come up, though - did you know that every camera tripod mount screw, old and new, is 1/4 Whitworth (BSF)? How on earth did that happen?