now sure if I understand what you want to change.

/addons/web_calendar/static/lib/fullcalendar/js/fullcalendar.js

changed:

setDefaults({

allDaySlot: true,

allDayText: 'all-day',

firstHour: 6,

slotMinutes: 15,

defaultEventMinutes: 120,

axisFormat: 'h(:mm)tt',

timeFormat: {

agenda: 'h:mm{ - h:mm}'

},

dragOpacity: {

agenda: .5

},

minTime: 7,

maxTime: 16,

slotEventOverlap: true

});