I’ve read through as many of the PCV Grommet threads as I can, and have yet to come across this particular question. On the 1980 Olds 350, originally I had the baffled valve covers with the D shaped hole for the peculiar (Standard Motors Part No. GV18) valve cover grommet. My aftermarket valve covers are baffled, but was wondering if it would work if I went with a traditional round pcv grommet and the alternative pcv valve (one that has the L-shaped vacuum port)? Obviously performance and the way it runs is most by important, but I HIGHLY doubt i’ll be able to finagle that odd grommet in. I’m looking to see if this would hinder, hurt, or work just fine. I appreciate any and all help . Enclosed a photo of valve covers further reference.

 

The engine doesn't care about the shape of the grommet, and with those aftermarket covers, you have no choice but to use the round grommet. You can get PCV valves with either straight or 90 deg ports that will fit.

 

This combo works nicely with those valve covers.

https://www.ss396.com/chevelle/CPX-9...hevelle&year=0