OK guys, need a little advice here. I'm an old Ford guy and used to machined surfaces for the valve covers. I tried ultra black with the stamped steel covers using Fel Pro cork gaskets. It leaked. What sealers have you guys had success with? I was thinking Permatex high tack, maybe.

Thanks,

Matt 

Dry valve cover surface + dry head surface = no leaks.
I've never seen any sealer that would work well with a cork gasket. The sealer acts like "butter", and lets the cork gasket slide around, and spit out.
Get your valve covers dry with brake cleaner(or similar product), and the head surface dry also, and there will be no leaks. You can also go with the cork gaskets that have a steel core, as they seem to work really well.
my 2c

I have my own method that works very well.  Doing this, I have NEVER had a failure or leak.

First CLEAN the head surface and valve cover gasket surface.  Brake parts cleaner will do a fine job.  Carb cleaner leaves a residue that can prevent proper adhesion.

Next, use HighTack (my favorite) or Indian Head or equivilent gasket adhesive/sealer on the valve cover, and put the gasket on the cover.  Let it set up for a few minutes.   Now put silicone RTV ( I prefer the blue for this application, but any will color do ) on the gasket to engine surface and install the cover.

Here is the logic.

The High Tack does not take up the irregular surface nearly as well as silicone.  Silicone is slipperly, and will cause the gasket to walk or slip out of place.  Oil on any surface prevents adhesion.

The gasket to the valve cover with HighTack will keep the gasket in place without it walking or slipping.  Granted if you ever change it in the future HighTack is had to remove.  But with the cover off the engine, it's easy to clean it up.  The silicone between the gasket and head take up irregular surfaces due to machining and warpage, and yet conforms very well to the rough surface of the head.  It is also easy to shear with a sideways motion with a few taps (not whacks) with a rubber hammer if you ever want to remove the cover.  The silicone cleans up fairly easily from the head.

So it holds in place, it conformes to surfaces, it seals, and it's easy to tear down in the future if needed.

My mothod works for me everytime, I clean the cover, if its a steel cover I check to make sure the rails are straight, especialy around the bolt holes, I use the thick steel core gaskets, I use 3-M adheasive and spray one side of the gasket and put it on the cover and let it dry, no movement that way, I put a very light smear of super black silicone on the head side of the gasket and let it "skin" then install, slightly tighten the bottom bolts then the tops then cris-cross, after maybe 10-20 miles I recheck the bolts, when I remove the covers I sometimes have to give it a slight tap to the cover with a rubber hammer to get them to release, they come off in one piece still attached to the cover. just put another smear back on when reinstalling. anips38614.8995949074

Joe, that's basicly the same thing I do.  Works very well.  You are just using a top quality gasket with the insert to prevent the gasket slipping.  It's a good thing.

 Have anyone ever used "The Right Stuff"? Made by Permatex. Oil, coolant & ATF resistant.that stuff really works great. I've used it to seal my intake on the front and back rail, and my rear end gasket, oil pan, ect. no leaks yet.

I have a tube of The Right Stuff. Seems to work pretty good. I have not used it on the valve covers yet though. I have been having a hard time keeping my valve covers from leaking and it has been driving me crazy. I bought the gaskets with the composite center and rubber type ribs on either side to prevent leaks but still have leaks. I may just drop back down and use some of the tricks listed here. Can't hurt.