Hello. I have a closed PCV system on my truck. I am never sure about which PCV valve to use on my 1956 235. I am currently using a Purolator PV679. The pintle inside of it has an "A" stamped on it. Do the letters have anything to do with the size of the spring tension or hole in the end of the PCV valve? Is the letter that's stamped on it indicative of the engine vacuum and engine size? I've also seen an "F" stamped on these too.

Does anyone know which one would be the best for my 235 that gets around 18" to 20" of idle vacuum when tuned? Should I also be concerned with the lettering on the inside of the PCV pintle?

Thank you. Mark


1956 Chevy 3200, 1/2 Ton, 235 CI
https://photos.app.goo.gl/TQQo1YnFjs3U7xB57