You need to punch them out. They tend to stick over time and you must be careful while punching them, avoid damaging the seats/housing. I self-fabricate a slightly " L " tipped bar to tap them.
Note the direction of the seals and do not install them reversely, it would result in difficulty in installing the valve cover over the spark plug tubes.
Thursday, June 7th, 2012 AT 2:04 PM