What is the timing setting for gM 2.8L V-6 engine ?

I believe all the 2.8's had computer controlled timing. IF its an earlier one that had a distributor there was a wire you disconnected on the firewall or a jumper you put in the diagnostic link port that put the system in 'set' mode at which point you set it to the factory spec which may have varied between models and years. After that its all up to the computer. If you want to change it you need to have a custom 'chip' for the computer if its a pre 96, a programmer for a 96+, or an aftermarket ecu.