Ignition Timing Adjustments??

[LexTite]

I need to adjust the ignition timing on a 90 ls. Though i see the markings atop the crank shaft, and #1 plug is first on the passenger side, how do i adjust it to 4 degrees? And being that theres no line for 4, can i just make a good guesstimation where 4 is. My goal is 4 degrees, if stock is close i may be able to leave, maybe right?

 

[sideshow]

if yr runnin std ecu theres nothin u can do easily

dont even bother unless u goto aftermarket ecu