My little Weed Eater tractor Is going on It's third engine. Factory engine was a 13 hp Tecumseh OHV. Had too many problems and was cheaper to have the shop put another used engine In. So they put In a 12 hp B&S flat head. Well this engine Is throwing heavy metal In It's oil and has always ran rough ever since I've had It. So I found a 14 hp B&S Vanguard V-Twin that Im gonna swap In. Im assuming It should be pretty easy. The tractor Is like new with zero rust. How hard does this sound like?