I have repowered my 1986 42ft Regal with twin 454hp gas engines. The gas in my starboard tank is bad, roughly 2yrs old. I’ve tried to drain the tank and remove the old gas with poor results. I was told by a friend that I can add 16 oz of seafoam per 5 gal of old gas. Than run the engine at 1000 rpm’s until all the old gas was used up. My question is will burning 35 gals of treated gas gum up my 4 barrel Harley carburetor?