I think you are right, Mikael. I have that book too, and also thought that does not seem right to me.
The idea is to see how much the hydraulic lifter is compressed when on the base circle of the cam - in simple terms of the number of threads of the rocker arm bolt. Think - if you tighten the bolt all the way and the push rod is still loose, you most certainly need a longer push rod.
So you are correct - the book has an error.
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