It helps when you don't abbreviate every thing, to make it clear what you are asking.

My ideia is to make cs 1.6 mechanicly the same in unreal engine. Only the visuals change. Is it possible? How?

Considering that Counter strike is a simple game, with basic rules and you want to visually change it; make new assets and program the game in unreal.

Just importing the models from cs, isn't going to work. The models are lower poly than this generation models, the textures where made for the old specular work flow (that uses 3 textures to make metal instead of one) and the models where made to work with the source engine; best to make all the art starting over from the beginning.

You could just import all the art, however it will look no better than in source and some could look worse because of the changes in the engines.

cs has very simple game play, that is why it's managed to remain one of the top FPS games, as it depends more on player skill than game mechanics to win a game.

You should start by learning how to load a character into Unreal and how the AI works, then study the gun mechanics of cs as it's the core mechanic in combat.

You can't use the code from Source because Unreal is a completely different engine.

The only way to do it would be to understand exactly what the code in Source is attempting to do and then to replicate the code in Unreal; so translating from Source to Unreal by fully understanding both engines.

Honestly it would be better and easier just to make your own Counter strike from scratch.

Is it possible? How?

Believe that cs = Counter Strike.

If you have a small amount of knowledge about UE4 and have played Counter Strike than yes your idea to "port" should be more of a test of time and accuracy than a test of skill

cs has very simple game play, that is why it's managed to remain one of the top FPS games

...be prepared to get a "Cease & Desist" from Valve though. They really don't like people doing this kind of thing...