Q&A

 Master

If you're working on your timing belt, or thinking about working on it, this site has a great tutorial plus other how-to's for the LS400
http://www.lexls.com/tutorials/engine/timingbelt.html

 Master

The ignition timing mark is on the crankshaft pulley and the black timing cover on the front of the engine. A timing light is used to adjust the ignition timing so that the spark produced by the ignition arrives into the cylinder at the precise time in the combustion cycle to ignite the gasoline in the cylinder to produce power.
Your LS 400 has two distributor caps and rotors and routing of the ignition wires is critical to ensure the engine runs properly and that the spark plug wires do not get damaged.