355 sbc and I can not get the dizzy to tighten. I am thinking it might be due to the decking of the block. No milling was done on the Edelbrock RPM heads and they were gotten new along with the matching intake. Should I maybe be using the thicker 120 intake gasket. The dizzy is a stock HEI built with MSD inners. Have no issues setting or lining up heads or intake.