Your Chevy has a coil over ignition system (no ignition distributor). The ignition system is fully controlled by the ignition/fuel injection control module. No adjustment necessary or possible. It is checked using a scan tool attached to the OBD2 diagnostic connector under the dash. The Engine uses a timing chain which te "timing/synchronization" of that is only checked during engine assembly.
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You Must Remove Intake, Intake Manifold, And Valve Cover. Once Done You Must Find TDC Of Cylinder 1 On The Compression Stroke.
Once This All Has Been Done Look At The Black Links On Your Timing Chain (Every 7th Link). These Black Links Should Match The Timing Marks On The Cam Sprokets. On The Exhaust Cam Sproket. The Sproket Will Read Delphi Right Side Up And Marks In Line On The Cylinder 1 Compression Stroke. As Long As This Is All In Line. The Motor Is In Time.