Fiat 600s workshop manual. It includes three large sections: car use, maintenance and characteristics. In this manual the specific procedures for this model appear, leaving aside as much as it can be considered common to all cars. It is in Spanish.
The Fiat 600 manual is good, but I am looking for more information about the engine's explodes, model 600s year 1980. With respect to the tuning there is not much in the manual.