Ok well I got the tool. Now, could you explain to me how to use it? When my machinst did my valve job, he did not shave metal off of the top of the valves, so now I have to disassemble the head and shave metal off of the valves that are too long. I am using the thinest shim and I am still compressing opening the valves when they are supposed to be closed. How much preload am I supposed to have on a 1990 300E motor and how do I use the tool to measure it? Thanks for all your help!