This is a FS-30 Surpass Four-Stroke Model Aircraft Glow Engine. Great for Scale and Sport models. FEATURES: Rear-mounted updraft carburetor Helix gear-driven camshaft supported by bronze bushings Ball bearing-supported crankshaft Ringed piston Two Year Warranty INCLUDES: One FS-30 Four-Stroke engine #F Four-Stroke Glow Plug One Muffler w/Header Pipe Instructions REQUIRES: Fuel: 5%-15% nitromethane with 18% lubricant. Synthetic, castor, or a synthetic/castor blend may be used. NOTE: Certain four-cycle fuels cannot be used due to low oil content. However, SOME four-cycle fuels such as the Wildcat 4-Cycle 15% (CATP9109) may be used because it has a 18% oil content. When choosing fuels for this engine, the modeler must be sure to select a fuel with at least a 18% lubricant content. Starting and Field Equipment. Propeller (see SPECS) SPECS: Displacement: 4.89cc (.299 cu in) Bore: 19.5mm (.767") Stroke: 16.4mm (.648") Power Output: 0.5 PS, 0.49HP at 10,000 RPM Weight with muffler: 10.4oz (295g) Weight without muffler: 9.8oz (278g) Practical RPM Range: 2,500 - 13,000 RPM Crankshaft Thread Size: 1/4-28 Valve Clearance: Between .04mm and .1mm (.0015" and .004"), Measured between the valve tip and rocker arm. Length: 84mm (3.31") from backplate to front of Drive Washer. Width: 29mm (1.14") width of engine neglecting the mounting flanges 36mm (1.42") mounting holes side-to-side on-center Height: 86.5mm (3.41") Suggested Prop(s): 9x6, 9x7, 10x4, or 10x6 Construction: Aluminum and aluminum alloys Needle Settings: High Speed: 2 - 2.5 turns out from fully closed Low Speed (air bleed screw): tip of screw 1/2 way across the small hole in the back of the carb COMMENTS: Some differences between a 4-stroke and 2-stroke engine: A 4-stroke is quieter A 4-stroke gets better fuel economy A 2-stroke generates more RPM (11,000-13,000 RPM with prop while 4-strokes rev to around 9,500 RPM) A 4-stroke generates much more torque and will swing a larger prop 4-strokes sound realistic (sounds like a REAL aircraft engine) kh6-27-02 upd NNA 10/27/02 ir/kh updt jxs 2/25/03 updt lmm 3/31/09