Drills dont quite do the job as they tend to loose power when the pressure starts to build and usually wont get oil to the rockers,when I primed the 351-W I put in my 55 fairlane I used a speed wrench which is hand powered and I could hear oil comming from the rockers. Those speed wrenches are uaually 1/2 inch drive so I adapted it down to use a 1/4 inch drive socket to turn the shaft and hand power was alot better then what a drill can do. Jeff