Hello,
I got a pair of reproduction valve covers for a 455 and a set of Dorman 42314 PCV/breather grommets. The holes in the valve covers have an internal 1/4" lip that would interfere with the geometry in the grommets. Did I get the right parts? Thanks.

 

Original Olds valve covers DO NOT have that lip...the grommets work just fine on the original covers. Doesn't really solve your problem but it's information.

 

Thank you. I will contact the manufacturer.