While Mr Walrus3 had a tale of woe--that's not the norm. The lifters can be reluctant to come out of the bore if there's a build up of sediment on the bottm half of each lifter--I use carb cleaner to get the coating dissolved (of course a thorough oil change/flush is required afterwards) and I use a tool made from the pliers Volvo used to supply--grind a groove in each of the jaws to catch the upper lip of the lifters and work them up and down. I've never had to pull a motor to change the cam. ALSO NOTE -- don't forget the spacer ring under the cam gear. Failure to move the ring to the new cam will result in a locked up motor.