PROBABLY DON'T--IT'S AUTOMATIC IN MOST CARS....SEE "MY ANSWERS" IN THIS LINK

https://www.2carpros.com/questions/2000-jeep-tj-noisy-lifter-piston-slap

IF THIS WERE AN OLDER CAR (BY MY STANDARDS...'70s ON BACK) OR SOME KIND OF RACE ENGINE...THEY MIGHT BE ADJUSTABLE

I CAN LINK YOU TO "HOW THEY SELF ADJUST" ALSO

http://www.youtube.com/watch?v=lorANZ1Tptw

LET ME KNOW IF THIS HELPS

THE MEDIC