What a silly question, of course, they can! Have you ever seen the Olympic line up for the 100-meter dash? Every single one of those guys is well over six feet tall and has legs taller than most bystanders. It is pretty simple science really; the longer the lever the more power can be obtained, and the longer your legs are the longer your stride can be. That is why the taller you are the faster you are.
However, “speed” is relative. Long distance does not require the same mechanics as a short distance. That is why you notice that when you watch the Olympics, sprinters are taller and distance runners are shorter. Again, this is pretty simple science, the taller you are the more you have to carry around and after a few miles, it sure does take a toll.
So can tall guys run faster? In shorter distances, they can, but in longer distances, shorter guys have a slight advantage. I don’t want you to think that your physical abilities relay solely upon your height. I believe that it is always he who works the hardest will run the fastest. The more work you put in equals the results that come out.