I hear the NPT size of the PCV valve is 1/4". I'm looking to replace it with an NPT to AN adapter to run a catch can with stainless braided lines instead of drilling out the PCV valve. Can anyone confirm that it's 1/4"?

 

It's definitely not 1/4 NPT, you can pull into a home Depot or parts house, pull the pcv with no tools except maybe a pair of pliars and take it inside to compare. I thought it was 1/2" but I can't remember... been a while since I did my catch can.