Bowflex question

[MaxxDaddy]

So I use a Bowflex to work out at home and if you're familiar with the device it has rods that supposedly are equivalent to a certain number of pounds of resistance. However, I get the feeling this is not the case when I'm doing 3 sets of 20 reps of curls at 35 pounds in each hand. Is there some sort of conversion I'm missing? Does it depend on the specific exercise you're doing? So you're aware, I'm 5'6" and 145 lbs.