How to set timming on chrysler grand voyager 2005 2.8. Where are the marks on the engine and pullies ?

No such thing a a Chrysler Grand Voyager. That was made by Plymouth and Plymouth was out of business in 2005. If you're talking about a Dodge Caravan, they didn't make a 2.8 in 2005

If it's like most modern cars, you can't adjust the timing like you could in the old days, because there's no distributor. Each cylinder has its own coil, and the timing is handled by computer, based on signals from the cam position sensor and/or the crankshaft position sensor. Timing is non-adjustable, unless you have the computer reprogrammed.

Why do you need to adjust the timing, anyway?