I look at it this way.
The companies that have to warranty emission control systems on new vehicles for a rather long period of time have adopted the metal clad style of seal for essentially all production vehicles for probably well over 10 years.
It’s a 3 piece design, so it should be more costly to produce, and yet these companies that are using literally millions and millions of them annually have determined they are superior to the technology used before.
That’s good enough for me.
I bought a new Dodge Dakota in 1993 with the 3.9 Magnum.
I sold it a couple years ago....... never even had a valve cover off.
Still not smoking or using oil at 147,000 miles.
It should have had the metal clad seals as OE.
The old Mopars with the all rubber seals usually had the seals all crumbled up into pieces, and down in the oil pan long before you got to that point.
The only time I see issues with the metal clad style seals is if the seal isn’t really the correct one for the size of the guide boss, or it got mangled up during installation.
As for whether it will sit flush on the bottom....... that’s really just determined by how tall the guide is, and how deep the seal is.
If the seal is deep enough to sit flush on the bottom great.
But they often don’t. The inside of the seal touches the top of the guide, and that’s as far as they go.
I don’t feel it’s the only style of seal that can be used....... but I do use them on “most” heads.
I’m a firm believer in using what you’re having good luck with.
You like umbrellas? White Teflon? Ring and band? All rubber?
I’m not trying to change anyone’s mind....... just keep using them.
If I had bought those Prostar heads...... would I have run them with the seals that they came with?
Sure.
