once you get it on there you have to put the service bolts in and tention it . you have to twist the outer ring by putting a bolt in service hole A . then pry with a screwdriver against that bolt and the cam until you can get a bolt in hole B .
then take bolt A out and leave bolt B in there tentioned.. take that bolt out when both cams are in place and torqued down .. it will lock into the exhaust cam.