Valve Cover Oil Leaks

Johnny Dart said
The trick is to glue the cork gasket to the valve cover.
This is usually where the gasket leaks.
Before you start take a ball peen hammer, and tap the bolt holes back out from the bottom.
You want a smooth, flat, clean surface.

I use Edelbrock gasgacinch.
Put glue around the valve cover mounting surface, and the one side of the gasket.
Let them tack up for a few minutes, and place the gasket on the vc.
Use your fingers to press the gasket and vc together, going several times around the gasket.
After the gasket is on, you can lay the vc on a bench, and put a small weight on top, and let it dry.
Now you have a gasket perfectly sealed to the vc.
After that put it on the motor dry. Torque down to the proper spec and order.

Done.
:)

This is exactly how I do it. The only extra step I take, is a light film of grease around the head side of the gasket once it sealed to the VC. This will allow you to remove the cover without tearing the cork.

One other thing to check, is the VC fitment. If you are running an aftermarket intake, they could be hitting the intake and not allowing them to seat properly.

To check this, put the cover on the head without the gasket, if it does not sit down on the head see where it's hitting, slowly grind those spots down until it sits nice and tight on the head.

Proceed with JD's instructions.