timing chain
If its an easy push on by hand and you want to tighten it up, put some red lock tite on the inside of the gear and crank mating area and slip it on, finish installing the cover slinger and damper an tighten it all together asap. When the loctite sets it will hold it without wobbling, and besides after you have the slinger and the damper on there with the bolt tightened down it wont move at all. It will likely be a SOB to remove in the future.