440 passenger side valve cover leaks!

[cv70chall]

I've recently upgraded from a small block to a 440 in my 70 Challenger and could not be happier.
However, I've had a pesky oil leak from both valve covers- mainly the passenger side- and have tried SEVERAL different types of valve cover gaskets as well as both aluminum and steel valve covers, both with the same result- leaks.
Anyone have a tip that I may have not tried that will work?

I've done the following:

Sealed gasket to valve cover with ultra grey
Sealed gasket to top of head with permatex
Allowed sealant on the valve cover to sit up to 2 days before subjecting it to fluids
Used Fel-Pro Cork and Moroso Rubber/ Steel Core gaskets. I plan on using the Mr. Gasket Ultra Seal Gaskets next.**

Help!!!!
 

[73440]

Both the valve cover and head need to to straight and matched to each other to seal well.
How do the joint faces look?

[Chryco Psycho]

Stock heads I bet , put a straight edge on it , I bet there is a 1/4 end to end , steel covers will flex more & are easier to seal than cast covers , no fun , I have been there

[mopar jack]

The pass  side is always hard to seal with the factory hypo exhaust. The manifold is almost touching the valve cover and if you look at any car with stock exhaust you will see scorched paint on the pass side valve cover. I measured the manifold temp with a pyrometer and it's over 600 degrees near the valve cover. I'm sure this causes a lot of distortion in the cover.

[cudabob496]

why not clean everything off, place a string of playdough on area of concern, then
put valve cover on head, and see how thick the playdough is. It would give you an idea
of how big the problem is.

Maybe there's one high point on head you could make lower?

[cv70chall]

Interesting idea with the playdough. It's next to impossible to really get in there to do any sanding if I have to. The surface looks fairly level but does have some small porous areas. I was thinking about laying a bit of Indian Head on the top rails of the heads and then go from there. That should seal up any porous areas ,right?

We had the original (ugly) stock covers on there and it didn't leak. Weird.
I've also used the exhaust manifold gaskets with the heat shields in hopes of reducing the heat near the valve covers.

[gafletch]

Permatex Right Stuff, 4 oz. can, $14.  But it sets quickly, so you may need an extra set of hands for valve covers. It's the only sealer that worked on my thermostat housing.

[Racer57]

I have cast valve covers. I used the Moroso gasket with the steel core and black high heat RTV silicone on both sides of the gasket after using Prep-Sol on the cover and head. Lots of problems before, none now.

[cudabob496]

Or you could use playdough like stuff and just lay the valve conver on a flat surface,
to see how flat it is.

[tman]

Don't think playdough is necessary.  The Mr Gasket Ultra seal work, but only for one season for me.  So in essence, the gasket work, but after heating up next to that exhaust manifold does hell with the gasket.  So I end up with a leaking right side syndrome like others here.  Before I had to do it every year until using Mr Gasket.  Now its every other year I have to change it.  I will be using the Superformance Carbon X who claim they can take very high temp.  We'll see if that claim is true. 
I haven't had to touch my left side VC gasket for years. 

[cudabob496]

my pass side was leaking, so used the Moroso brand, with some sticky stuff to hold it in place
on the valve cover, and no more leaks.

[cv70chall]

Got the Moroso valve covers yesterday. Took a small sanding stone attachment with my cordless drill to the inside lip/ edges of the covers to rough them up, then cleaned with brake cleaner.
Applied Indian Head generously and then set the gaskets (they needed to be slightly trimmed on one side to sit properly) using flat sticks with multiple clamps to hold them right where I want them while the Indian Head dries. Did one last night and the second one this morning. -Give it plenty of time to dry.
Tonight, I am finger-applying Ultra Black/ Ultra Grey to the tops of the heads (after a thorough cleaning) to fill in some of the rough spots and get a nice level surface. This will be allowed to dry at least until Saturday afternoon at which point I will install the valve covers and tighten them down- just tighter than snug.
After that- fingers crossed.
I think I've done all I can to try and beat this.

[bc3j]

Used an unconventional approach to sealing the valve covers. I have a stock 383 with no modifications to the motor. I used new steel valve covers and used Right Stuff with no gasket to seal them. The entire valve train was checked and torqued along with the head bolts before the covers were put in place. The valve covers will be tuff to remove but I have no leaks. Talked over the pros and cons of going this way with my mechanic who is an old school mopar guy and decided to do it since there should be no good reason to have to constantly remove the valve covers. This won't work for motors with solid lifters. Anyway worked for me zero leaks.