Friends, 
I understand that the early '90's Vanagon had a Digifant I fuel/spark system. I have that system on a '91 Jetta and I am having trouble setting the timing. If I do it according to the Bentley (Jetta) it comes out way wrong. So here are my questions (and how do these procedures compare with the Bentley for Vanagon?):
According to the Bentley the timing light's battery power supply is supposed to be connected to the battery + and the igniton coil - post (I don't understand why?)
Then after disconnecting the coolant sensor start the engine and let it warm up.
Then rev the engine 2100 and let it return to idle, do this 4 times (clears the momory, by-passes hot-start, fast-idle function).
Then rev the engine to 2000 to 2500 rpm and set timing to 6 BTDC.
Finally turn off engine reconnect coolant temp sensor and reset the Digifant to its base setting.(disconnecting the crankacase vent hose, pugging it, starting engine, disconnecting coolant temp sensor, let idle for 1 minute, turn off engine, reconnect temp sensor, unplug hose and reconnect).

Does that procedure agree with that given for the Digifant I for the Vanagon? If so, does anyone know why the resulting timing seems so far off of what it should be?

Please excuse my bringing a question about a Jetta to this esteemed list, but I haven't had much success with other resources. In mitigation, I do also own a '75 VW Westphalia but it thankfully uses the L-Jetronic system.

Roland Finston