How to create 3D model of working engines

I know that there are many working engine kits and that some people 3D-printed working engines. How can I get information that I need for an engine. For example, I wish to create a working model of the 1950s-1970s Chevy V8 small block engine with carburetor. It will be a simplified model. Someone 3D-printed a Chevy V8 engine for late model Corvette and Camaro with fuel injection.