Knocking/tapping sound especially when I shift

Need a little more info With car setting still and revving up engine does the knock get louder or stay the same Are you sure it is a knocking sound or is it more like a rattle or ticking sound If you are sure it is a knock , with the car setting still raise the hood and slowly give it gas If the knock gets louder and faster that is a rod knock and you will need to tear the engine down and repair If the knock stays the same but get louder then that is more likely what is called a main bearing knock Not as dangerous on the engine as the rod knock but still needs to be pulled down to fix I would do either a complete rebuild or buy an running engine complete