Does system-config time actually set your system to be an NTP server? I think it is just a client config tool.
Get it working first as a client, then add to your /etc/ntp.conf as follows:
restrict lan-network-addr mask lan-network-mask nomodify notrap
where lan-network-addr is the first address of your client network and lan-network-mask is its mask, e.g.
restrict 192.168.2.0 mask 255.255.255.0 nomodify notrap
Clients on that network will then be able to sync to your ntp server, provided your firewall has port 123 (ntp) open.
Paul.
