Leaking Riser Gaskets on 454 BB

" My 1997 SeaMaxx 454 Big bloc

" My 1997 SeaMaxx 454 Big block has had chronic leaking gaskets where the riser extension meets the manifold and where the riser itself meets the extension. It has ruined one set of manifolds and I want to prevent losing another set. I am replacing the gaskets myself this time, but want to know if anyone would recommend double-gaskets, and what kind (if any) gasket sealant I should use. It seems that I get a lot of suction from this monster that may tend to suck water through the gaskets and hasten their demise. This set of gaskets started leaking in less than a full season (about 75 hours). "

" Be sure both mating surfaces

" Be sure both mating surfaces are in good condition, well cleaned (prep with a sanding block). Do not buy the cheap paper fiber gaskets you will get at most parts places. Seek out real mercruiser gaskets which look shiny and metallic coated. Typically no sealant is used for these. Tighten well at installation. Use it a few times then re-tighten to spec torque values ( I don't have my book, it's on my boat). Re-check torque every few months as the gasket compresses. "