The kidneys keep the valves from falling and the head from moving around. Tommi 26.1.2014, 20:12 Full size 1000 × 563 pixels The kidneys keep the valves from falling and the head from moving around. Previous imageCutting the kidney shaped pieces for the combustion chamber. Next imageDrilling out screw holes in the tank. Leave a Reply Cancel reply Your email address will not be published. Required fields are marked *CommentName* Email* Website Save my name, email, and site URL in my browser for next time I post a comment. Notify me of new posts by email.