Whenever I hear the word valve seal I get PISSED OFF. I needed to change one on my car one day (not a camaro, dont shoot me i do own one though) and set it to TDC on number 2. did the compressed air thing... removed the keepers all going ok.... then the air pressure rotated the engine WOW and bye bye goes my valve..ooh boy the swearing could be heard 5 blocks away my 1 hour job became a full day.now ive learned my lesson to pin the goddamn flexplate with some visegrips or something to keep it from turning in the future..

 

Holy cow man, what kind of pressure were you running? Ive only got 2 plugs removed and about 75 psi....no probs with her turning over. Maybe cause Ive got the other plugs still in....