yes this is something i have been looking for, in my model i have tried to design 4 cylinder engine but i think i have stretched crank too much, i’ve made gears to connect crank to cam but haven’t connected them yet because i might have to change design of cam shaft according to firing order of engine, biggest problem is i don’t know how to make those valves open by camshaft without making animations to them and how to press spring of valves, i have tried to move pushing rode by cam using shrinkwrap constraint and it worked i have not included that in my main project i 've been trying it on my another file, i have just started learning blender from last 15 days i know that’s too early for me to make this kinds of projects but i love engines and mechanisms.
here’s my file, https://ufile.io/a1tezd96
sorry website didn’t allowed me to upload file directly saying i’m a new user.
i have tried to under stand mechanism i want in some conversations here but i really didn’t understood them because my english is weak.
thank you for your time i really appreciate your help.