I own a 98 Honda civic ex with a 1.6 L 4-cylinder engine in it. Im thinking about doing modifications on it and im having trouble deciding what engine to put in it. I heard from someone that I could just take the head of a B16a engine and put it on the engine I currently have or the same with the head of a B18c1 engine.

 

That someone is misleading you unless your car already has had an engine swap to the B series.

B series heads will not fit D series blocks.

You just might want to chack your engine stamp so you know what you have currently.