3D Hobby Shop YAK55, Assembly Manual, Page: 36 / 46

Start small and work your way up to the required opening size, adjusting your work as necessary to
obtain a clean installation and the ability to easily slip the cowl onto the plane with the engine and exhaust
mounted. Once you get to the point where the cowl can be slipped onto the airframe and engine you can
enlarge the holes slightly to allow for vibration during flight.
Note the evolution of the spark plug hole in the photos below in the center and on the right from providing
just enough opening for the tip of the plug to include room for the cap and wire. We have started with
only a small hole for the tip of the plug, enlarging the hole for the plug wire as required. Make sure your
plug wire cannot contact the cowl at the rear of the plug wire opening.
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