I installed mine with no machining as well. I just ground the webbing out of the valve cover. I fully seated them and backed them off 1/4 of a turn. They protrude through the nut about an eighth of an inch.....

I've installed about 10 sets of them this way over the past few years.

 

Yep just grind the webbing out and they will fit just fine. We just used a die ginder on vinny's 12 valve covers just make sure you clean them out good with air and brakekleen

 

 

Thanks!! Have ya'll install any with valve cover breathers?