WA 450 komatsu over head adjustment issues

hey guys, why is it that every time I touch a dang Cummings I keep having issues running the over head, not sure what the deal is but every time I build motors with top stop injectors I have issues with the motor locking down dureing rotation of over head adjust ment , im going buy the a b c on the access. drive pully, I do the inject. on one hole an then the valves on another an then turn the motor to next marks an do them an so on, seems to all go well till I get to like the last holes an the motor locks down, ive set the valves at correct settings an the injects at 6 in lbs. after a few hrs monkeying with the cummins motors then every thing finally goes threw an its ok, WHATS THE DEAL HERE, ive had a issue of getting oil in the water with the L10 in our loader an pulled the head off an got a head set an new head due to crack, an even tho I didn't have fuel in the head dureing adjustment procedures I went ahead an bottomed out each injector few times just to be sure. just not sure why that every time I touch a Cummings weather its a 855 or 350 or 290 or L10 whats the deal screwing withem an just all of a sudden it all adjusts out rite. ive tried to adjust out the the valves first an ive tried to adjust out the injectors first. still locks down till ya have to back everything off

WA 450 komatsu over head adjustment issues