I tried in the past to paint this engine using different formats with no success. Finally the use of charcoal has worked well with this image. I have used a different method to guide the middle phase of this drawing as the image was decreasing in size whilst I worked on it. The scale from the photograph to the drawing was increased by 3.4. Although painstakingly slow this resolved the problem. The 6th bolt from the left is the pivotal point of the whole drawing.