[Mike Taylor 3601]

I would make sure that there is no binding of pushrod against guide plate,head etc where it has pushrod not seated in pushrod seat,like some others said when you have the full pressure of springs can lose lift.
If tip of valve is higher on your head that loses lift,that causes tip of valve and rocker stud to be closer,which puts tip of valve closer towards intake and roller of rocker out towards exhaust which is same as reducing rocker ratio.
Mike Taylor 3601