Briggs & Stratton 305442-0636-F1 Horizontal Vanguard V-Twin OHV Engine, 479cc, 16.0 Gross HP, 1″ x 3″ Crankshaft, 1/4″ Keyway, 3/8″-24 Drilled & Tapped, 6.95 qt Fuel Tank, No Muffler