Introduction to engines The reliability and performance of any engine is dependant on the proper care of it - from the first day out of the box. Always read the instructions that are supplied with your engine before trying to run it. What is 'Running In'? Running in helps all the moving parts to bed-in together whilst causing as little wear as possible and, done correctly, will reward you with an engine that is reliable, dependable and with a longer service life. It is a process that involves running the engine with only a light load - by choosing a propeller at the low pitch end of the suggested range - and for only short periods of time with a 'rich' mixture (more fuel, less air) and allowing the engine to cool between runs. Engines with an 'ABC construction (an Aluminium piston running in a Brass liner with a Chrome plated bore) require very little running in. It is still a worthwhile procedure however, as it allows the newcomer to the hobby to become familiar with the running characteristics of his/her engine before installing it in a model. Running a Glow Engine For The First Time Firstly, the engine must be securely mounted to a suitable bench or stand. Never run an engine in a vice - it is extremely dangerous and will severely damage the engine. Attach a pushrod to the throttle lever so that it can be controlled from a safe distance behind the propeller. Connect a suitable fuel tank (see page 11-14) with silicone tubing (page 11-15) and fill it with the recommended fuel (see page 16-2). Fit a suitable propeller - use the Selection Chart on page 6-2 or follow the manufacturer's recommendations and open the needle valve three full turns from its completely closed position. Open the throttle completely and, with a finger placed over the air intake, turn the propeller a couple of times to draw the fuel up into the engine. Close the throttle to just above idle and attach a suitable glow clip and power supply or glowstart (see page 11 -17) and spin the engine over using an electric starter (see below and page 11-19). Do this in short bursts until the engine fires and runs. Of course, an engine can be started by hand by simply 'flicking' the propeller using suitably protected fingers (see page 11-19 for Finger Guards) but it is safer and easier to use a purpose made engine starter. Once running, open the throttle fully, then adjust the needle valve, turning it gradually clockwise until the engine reaches its maximum revs, then 'richen' the mixture by turning the needle valve anticlockwise until the revs can just be heard to drop off - usually two or three 'clicks'. For the first 15 minutes' running, the engine speed should be varied between full power and idle, so that the engine holds its temperature for a while and then can cool down as the speed drops off. The engine can now be run normally - either on the test bench, or in a model - with the needle kept 2 or 3 clicks rich for the first hours running.

How a Two Stroke Engine Works For their size, a two stroke engine -one that has a firing stroke once every revolution - is fast revving and powerful. Mechanically, they are relatively simple, with ports for timing rather than the moving valves found on a four stroke. The years of development that have gone into refining the production of model two stroke engines means that today's engines are reliable, easy starting, easy to adjust and represent excellent value for money. Shown here are step-by-step diagrams showing how they work. To start, the engine must be turned over by flicking the prop. This moves the piston up sucking the fuel/air mixture from the carb through the just opened crankshaft port. At the top of the piston travel, the fuel/air mixture fills the whole of the volume below the piston and the crankshaft valve is now closed. This completes the induction stroke. The piston now starts to move downwards compressing the fuel/air charge beneath it. The downward movement of the piston has now uncovered the transfer port so that the compressed fuel/air charge escapes into the cylinder above the piston. As the crankshaft rotates further, the piston rises to shut off the transfer port, trapping the fuel/air mixture above the piston. The crankshaft port is now open to suck in a fresh fuel/air charge. Approaching top dead centre, the now highly compressed fuel/air mixture is on the point of being fired - either by the heat of a glow plug element, or spontaneously in the case of a diesel. The piston is now moving downwards, driven by the pressure developed by the burning of the fuel. At mid-stroke the piston has reached its maximum speed. Meanwhile, the crankshaft valve has trapped the fresh fuel/air charge in the crankcase. The downward movement of the piston opens the exhaust port and the burnt fuel escapes, assisted by the incoming fuel/air mixture as the transfer port opens. With the piston at the bottom of its stroke, the transfer port is open for the fuel/air mixture. The exhaust stroke is now finished and as the piston begins to rise, the cycle is repeated from step