First question I have is why does your wife think the timing needs to be adjusted?

But here is the procedure. I've never done it with an electronic ignition, though. First you need to clean off the outside edge of the lower fanbelt pulley. There are timing marks on there although if it hasn't been timed in awhile they are surely covered by grime. Also, you will need to find the timing mark on the timing cover. It is on the front close to the pulley, looking from the front of the engine it will be at about 10 oclock in reference to the pulley. To adjust the timing you will need a 7/16 wrench. I like to use a box end. Loosen the bolt under the distributor slightly. Start the engine and time it with small adjustments by rotating the distributor. I like to set the timing at about 15-18 degrees BTDC @ ~1000 rpm.

If you see the timing mark on the pulley jumping around you most likely have a failing timing gear.

Have fun,

Ron Tewksbury
1968 122s ?66K
1987 245DL 131K
1989 745GL 165K