well some cars are on hydraulic tappets, like cossies etc...

but some are adjustable tappets, such as old OHV rattler fiestas etc...

i remember my mate rebuilding his type-R scooby, and he hsd to strip it down as he didnt set the valve clearences properley which would make you think they are adjustable. in which cse you wouldent need to replace them jsut adjust em.