Cam stuff:
This is the cam sprocket attached. As noted, its a taper fit on the cam so held on by the torque of the bolt.
This is the locking plate. Both cams have flats milled on to them such that the locking plate only fits one way round, and its sandwiched between the sprocket and the washer under the bolt head.
This is the locking plate and bolt in place without the sprocket. The locking plate is loosely pushed on to the flats on the cam and then the bolt holds it in place
The right hand bank 1 cam will happily just sit there with no belt or sprocket. The left hand bank 2 cam though will rotate clockwise with very little provocation (especially on the V6), but generally won't move when you just take the belt off so its simple enough to dismantle everything to do the belt without it escaping. But, as soon as you loosen the inlet cam and chain tensioner, it will jump round on its own thus I keep the bar in at all times except when removing or refitting sprockets, the belt, or the water pump (because the bar gets in the way). Its not that important when only doing the belt though.
The engine in this pic ^ is sitting on a pallet with no timing gear and both cams are still lined up. When I pull it apart to do the tensioners, that's when I'll put the bar pack in
