Recurrent air leak at base of carburetor

LA 360 (non-Magnum) with Edelbrock Performer intake and ThermoQuad. I'll tighten down the carb bolts but they seem to loosen up again, causing a random miss at idle and low RPM. This has happened twice now. Maybe it is some problem with the base gasket shrinking? Should I should use some Copper Coat gasket spray? Any suggestions appreciated.