Your obviously talking about a very cheap rototiller, since Northern sells B&S 5.5 HP horizontal engines for as little as $224.99. A decent tiller designed to last will cost considerably more then just a bare engine. Of course, it really depends to on the quality of the engine, the quality is all over the place. I have yet to have a quality Kohler, Honda or Robin throw a rod. I have had them eventually wear out.