i have working on my engine and noticed that there are some rocker arm tapping and think that the lifters are not pumping up. it really has no mileage on the engine possibly 4hrs total and i think that the lifters were not properly broken in. but just incase it is not. are there different pushrod lenghts for the 400ho then the 400? when i rebuilt it, the kit had some new rods so i used them without thinking that there might be a difference. thanks.