how far advanced should the timeing show on a computer reader in the 3.4 v 6 on 2002 Oldsmobile Alero

problem started with car after a major head gasget blow replaced it but extreamly noisy in motor timeing showing about 21 advanced

Asked by for the 2002 Oldsmobile Alero
The computer is smarter than we are it looks at load, air coming in, engine temperature ect.... It calculates timing requirements to give best power, fuel economy and keep emissions lowest. I look at the value on a scan tool if there is a drivability issue for loss of power.
1 more answer
thats about right. it will vary according to load. what is the issue you are having??