Valve cover leak, Help!

I just replaced the stock valve covers with mopar cast aluminum. They look cool but can not get them to not stop leaking. I used the mopar steel/rubber gaskets and think this is the problem or maybe I over tightened them. I don't have a inch torque wrench. What can I get local at say Auto Zone, NAPA or somewhere like that that may be thicker and do a better job. I drove about 6 miles last night, pulled in the garage and boy did it smell up the whole place.