The FAA has updated their manuals "Aviation Maintenance Technician Handbook- Airframe, Volumes 1 & 2. These cover a wide range of subjects that are useful to car builders. Volume 1, chapter 4.1 covers metalwork and Volume 2 covers electronics and wiring. Download them for reference.
The Powerplant manuals are a good source of information on engines. Although they are aircraft engines, the operating principles are the same so they are useful.
