i think your talking about valve lifters?, if you are, they are under the intake. i think they are nonadjustable on the newer cars. to change them, you have to pull the valve pans, loosen the rockers, take the intake off, take out the push rods and take out the lifters. before you replace the lifters, make sure you pump each 1 up with clean engine oil. it depends on where you take your car to have it worked on, just how much they charge you.