Insert the following parameters into your iCal link to specify days ahead and days back.

&ical_days_ahead=300 (will allow you to pull specified # of day's events in advance)

&ical_days_back=100  (will allow you to pull specified # of day's events in the past)

Here is an example link including these parameters:

http://www.calendarwiz.com/CalendarWiz_iCal.php?crd=yourcalendaridentifier&ical_days_back=100&ical_days_ahead=300

Note: be sure to insert your unique calendar identifier name where is says "yourcalendaridentifier"


More info on customizing iCal feeds:

Create an iCal feed for a single category or combination of categories:

Single Category or Combination of Categories

Create an iCal feed for private categories:

Private iCal Feed