I flew my fourstar with an Irvine Q72. Excellent engine, excellent performance. Now it has two OS LA 40's after a switch failure resulted in a serious nose job. Think about setting the engine as low in the fuselage ( low thrust line) as possible. Remember, the carb jet should be as close to inline with the centerline of the tank as possible or just a tad above. On my first fourstar ( a fourty with a Fox fifty) this helped with consistency with the fuel feed.