Re: 2008 mercury 250pro xs head torque specs and pattern
You can look up torque specs for bolts on www. Values are usually stated for clean and dry but sometimes charts have numbers with lube, like Locktite thread fastener applied which prevents loosening and reduces corrosion.
On the pattern, most heads are torqued in 3 steps, 1/3 of the pressure in each step and the pattern is X starting at the center and working out each time to the end of the head. Some folks put them on dry and especially on used marine equipment, some folks use a special head gasket sealer like Kopper Koat which is in spray or can and is specifically made for securing all head gaskets....popular at auto parts store.
HTH,
Mark