can anyone tell me in the timing can be set manually?, and if so how..thanks..

 

The base timing is preset when the engine is manufactured, no adjustment is possible. Timing advance and retard are accomplished through the ECM.

 

good answer.

some motors that are PCM controlled still may be manually adjusted, the 4.6 mustang for example. i am not aware of anything like this for the chevy side.

 

no you can't, the way the opti spark is set up it sets the time. if you go to napas website and read up on the opti it'll tell you all you need to know. its actually kinda genious what they did with it, too bad its such a pain in the *** sometimes like when you have to replace it when a coolant line bursts like mine, lol.

 

The LT1 is timed through the pcm. Only MSD offers a opti that can be adjusted for timing but it's a waste of money because the pcm will re-adjust the timeing.