Dr Dave's original cam timing thread was getting a bit long in the tooth and confusing so here is the same information again, but condensed and simplified plus some additions of my own. Some of the images are taken from the original thread, but I have replaced or updated others. Thanks to all who provided them originally!
Timing Marks Plus Some Hints and Tips.
K16 Cam Timing Position.
K8 Cam Timing Position.
Crank Pulley in Timing (Safe) Position.
Timing Dots on Crank Sprocket Behind Crank Pulley.
Inlet Cam Pulley Drive Pin Position.
Exhaust Cam Pulley Drive Pin Position.
VVC Front Cam Pulleys with Locking Tool in Position.
VVC Rear Cam Pulleys. (This position is used for setting timing. Before cam carrier removal, pulleys should be positioned with marks facing outwards)
Cam Pulley Holding Tool for Bolt Removal / Tightening
Cam Pulley Tool for Fixing Position during Belt Fitting
Tips when working on cam timing related parts:
* Before removing the belt, make sure that the engine is set to its timing marks. In this position, the crankshaft is at 90 degrees before TDC and all the pistons are half way down their bores. This means that the cams can be turned at will without damaging the valves. Cam pulley marks can be seen after removing upper belt cover.
* Only turn the engine over using the crank pulley bolt or by rocking the car with it in gear. Do not turn it using the cam pulley bolts. Removing the spark plugs will make things easier.
* If you need to undo the crank pulley bolt, do it before removing the belt and make sure that the cam locking tool is NOT in position between the pulleys or you risk damaging the belt or even bending the valves if the crank should turn a bit.
* Never turn the crank with the head removed unless the liners are first clamped in position. If the timing position has been disturbed, an alternative would be to refit the head with no cams installed so that the valves are shut and can not be damaged.
* The cam timing tool is only required to assist in final fitting of the cam belt. It is not required at any other time - if the cams move, this is not a problem with the crank in its Safe (Timing) position and they can easily be turned back when required.
* Do not use the cam timing tool between the pulleys to hold them while undoing the bolts. The tool to use is either one that picks up on the pulley spokes or you can use some types of oil filter strap wrench (not the chain type) wrapped around the cam pully.
* Cam belts can fail internally and still look new on the outside. If a belt has been contaminated with any fluid (including water!) or pinched it should be replaced.
* Final belt tension should only be set after rotating the engine a couple of turns by hand, stopping at the timing position.
* Cam timing notch is on the front flange of the crank pulley as shown and positions the crank at 90 Degrees BTDC (Safe or Timing position). Painting the marks white will help you to see them.
* A mark may also be found on the rear flange of the crank pulley. This was used with the timing degree scale on the cover to show ignition timing.
* The most reliable crank timing mark is that indicated by the two dots on the crank sprocket. The rim of the crank pulley has been known to slip round on the hub giving a false indication. Also, the pulley location feature is very small and it is possible to damage it when refitting, again resulting in an incorrect timing mark position. However, the dots on the sprocket can still give a false reading if the pulley location feature has become damaged for some reason, so if in any doubt check that all the pistons are at exactly the same position in their bores.