Water allows the gasket to expand and when it dries, it kinda sticks to the mating surfaces. Been there done that, and barely works IMHO. The best luck I've had, was using a bead od ultra-copper on the gasket surface and bolting it down, then letting it set for 24 hours. On my SBC, I use Earls PressureMaster exhaust gaskets (aluminum frame around a graphite impregnated gasket insert), too bad there is not one available for our Buicks. The other gasket choice is from NAPA, their NitroSeal exhaust gasket is a graphite impregnated composition exhaust gasket. The idea behind graphite imprenated, is that when the manifold/engine heats up, the graphite flows and takes up space in the area of the gaps.