Detroits are ok for constant speed/ stationary engines, like gens, a/ comps, etc. good on fuel and run cool, but don't lug to save it's life. if it has the mechanical fuel pump on it, pull it off ( has 2 bolts on it) and check the little square drive sleave, and the condition of the pump and engine drives. and remember they leak oil.... if it doesn't it's out of oil!!!