You need to put some washers first to set it up. Every car is different. Once alligned make some spacers out of some round stock or just leave the washers in there.
.....could not of said it any better. Sometimes it makes more sense to space the entire upper contol arm an extra 1/8" or 1/4'' further forward or rearward for optimum caster adjustment depending on application...race or street
I still have my 1/8" thick washers in mine. One of there days I will have some aluminum spacers made.