Internal combustion engine

An engine block comprising a casting including side walls extending along a row of cylinders, and front and rear walls extending between said side walls in front of said row of cylinders said side-, front- and rear walls having top flange surfaces for mounting a cylinder head and bottom flange surfaces for mounting on oil pan to said engine block, said side walls having sections extending forwardly beyond said front wall and defining therebetween a timing chamber adapted to receive the timing gear for driving a cam shaft mounted on said cylinder head, said timing chamber having top and bottom openings, and a rib extending between the lower ends of said side wall projections and limiting said bottom opening.