Leaking valve covers and broken Mopar Performance tabs

I know lots of guys fight with leaking valve covers, especially when switching over to cast aluminum covers. Also seen many threads about the corner tabs being cracked and broken on the Mopar Performance covers. Some of you guys know and many don't- the rocker rails on most Chrysler heads are bowed high in the middle pretty badly most of the time. The only proper fix is to machine the rocker rail flat, meaning your engine shop needs a mill and a good adjustable head fixture.

So, if this is something that happens to you-


or you fight constant valve cover leaks with every trick in the book....
this is why-
After taking off .060" its still not flat at outer corners. Many crank down on the bolts until they get snug and by then its too late. The covers are thin and not made to flex down, so they crack instead.


Example #2- the dark areas are still -.040" low-


Larger view- note the left side of the rocker rail is machined but its not even touching the right hand side yet


So, if your heads at the machine shop, ask them to machine the rocker cover rails and save yourself some headaches. This is a standard Chrysler operation in my shop and well worth the time and effort.