When I enter an event in Calendar running Maverick, I am limited to no more than 3 hours. How can I enter an event in Calendar longer than 3hours?

Are you referring to the suggested meeting durations that pop-up when you click on the End Time field on a new event?

If so, those are just suggestions. if your events are longer than that, just type in an end time and it will override the menu options.

Typing over just reverts the number back to the starting time. I can not get a four hour or longer event scheduled.