No, your cam timing controls that. Worst case, I guess you could crank down on the adjuster so much that the valve stays open, but you wouldn't be following the instructions very well. If you are uncomfortable marking your balancer and turning the engine in 90 degree increments, do this:

Install all the pushrods and make sure they are seated in the lifter. Starting at #1, turn the engine until the exhaust valve starts to open (watch the tips of the pushrods as you turn the engine to tell when the exhaust valve is opening). Install the rocker and adjust the intake valve for #1. Turn the engine until the intake valve opens and starts to close and adjust the #1 exhaust valve. Continue until all 16 are adjusted. This method requires more turning of the engine, but you can see everything topside.