I wondered the same thing. I would think that you would want to pull a valve cover and see if the cam timing marks are lined up. If they are I would think you could do that. I am just going off what was said in the "Lost Timing Reference" video on the web. My passenger cover is only sitting on the head so I may back the pulley to the reference mark on the cover, pull off the cover and see if I see the cam timing marks.