In Aircorps Library, under P-40, look for drawing 75-41-001. It is the installation of the P&W R1830-13 & 17 on the P-36A. It describes in detail the engine installation, cowling, mount, controls, accessories, etc. In addition, that drawing also contains the complete airplane's fuel system including the fuel tanks and plumbing. I am sure that further digging in the Aircorps Library P-40 site will result in more information.