timing chain +4 degrees 0 or -4degrees

[sext7366]

on a timing chain with different options is this to adjust cam timing, or does it affect overall ignition timing, and on a street 383 headers single plane and 800cfm carb should I set it standard, or would a different setting be beneficial?

[Chryco Psycho]

it is to adjust cam timing
advancing the cam help bottom end power , retarding helps top end power , if the right cam is selected it should go in on the manufacturers recommended CL