Valve cover torque specs

I know this is super old by now...but I've had the same thing when bolting these (cast alm valve cvrs) to an Edelbrock performer (or similar) - you MUST file a relief in the valve cover near the intake manifold runners. Some more than others, some so little it will feel "ok" when bolting down. A tiny gap is enough. I first discovered this via a flash fire on the header from oil hitting it.
I said file for a reason - you run the risk of an uneven and/or too deep cut with a power tool. A large file is great for this, as you can easily control the profile and depth of the cut.
I've heard of, but have never had to do, double cork gasket helping with this.