I'm replacing the idler arm on my 91 camaro z-28 with a 350 and I cannot figure out how to set the height. I've got a Chiltons manual and it says it's very critical to get it the same as the old one. I've tried to screw the upper half in and out like the manual says but it does not change. Is the manual wrong or do I have a defective part. Has any one else ever changed this? I've also changed the tie rods ( inner and outer ) and ceter link ( drag link ). I will be taking the car in for a front end alingment, so will they take care of this for me, or would this be an extra charge? Thanks to all that away!