Dan,

Yes, Just as Jim described. The cam sprockets can be tricky.

From your post it sounds is if you are under the impression your existing shims will all the same thickness. That is not the case. They will be all over the range. As Jim stated, since you have no reference point on the existing shims, you will need to take it apart after the measurement or read the markings on the shims to find out exactly how many replacements you will need. Remember to replace the shim with the marking up so the valve stem does not wear off the marking.

My bet is will have to purchase less than four shims. The factory spec provides a range so there is always a way to distribute the shims you have to minimize the amount you need to purchase.

Yes and always save those old shims, as Jim stated.

Tinker