Correct breather for cast aluminum valve covers

CudaChick1968 said

The covers are a half inch thick where the PCV knock out boss is and the manufacturer sadly discontinued the right grommets a few years ago. The ones sold now (not Mopar-specific) have a seating groove/channel that is much too narrow to seat in there properly.

The only one I can find lately for my customers is a set with a traditional PCV grommet and a plug. Unfortunately that grommet's center hole is too small for your big factory breather.
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I bet you could cut the bottom off of the plug with a band saw though. It would be quicker and easier than trying to drill a bigger hole in the grommet.

I don't recall the name of the place where I bought this set but do remember it's in East Moline, Illinois if that helps (I was born in Moline).

I hope this gets you back on the road!

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Thanks CudaChick. I don’t know what the deal is with mine, but I measured .556 on the cover and .440 on the neck of the breather. Then there’s the beveled lip on the grommet that’s supposed to extend past the boss, so that makes the even smaller. Is there a chance the hole was cut in the wrong position? Like that particular position wasn’t intended for the breather but something else? I noticed the valve cover thickness at the oil cap hole is much thinner than the breather hole.

The ones I got from Mancini Racing looked just like the one you have pictured with the end plugged, so I cut the end to open it up. Since the beveled part didn’t push all the way through to lock it in, I attached some grip tape (like on a skateboard) with RTV and stuck it in. Unfortunately the RTV didn’t work like I’d hoped it would.

I was thinking of doing the same thing, except maybe with Permatex or a bearing mount product. What is the depth of the grommet with the plugged end? I’m hoping it’s deeper than the one I got from Mancini.