360 intake manifold gaskets?

Are you using the metal gaskets or the print-o-seal type?

Are you using an aftermarket intake manifold?

Did you remove the dowel/roll pin from the block?

Are you retorquing after a heat cycle? Are you torquing to spec at all?

It is advisable with the black RTV to give it a couple of minutes to start to set up before installing the intake manifold. Even with the intake torqued down there is a gap here that must be filled, so make sure your RTV is 1/4" thick at least.

Steve