The webtier has two main components the http server and the cache server. This doc explains the steps to change ports on the http server with no cache server installed. You will install a http server only if you have no need for a cache server, like a token service, or credit card clearing application. These types of applications can not cache any data and do not need the extra component installed to cause greater security risk.
set your instance home
cd $INSTANCE_HOME/ohs/bin
chown root .apachectl
chmod 6750 .apachectl
Change your port in your httpd.conf file or your gui Middleware control and restart the httpd component