on a 91 z28 305 tpi with the est unplugged and base timing dead on 6 deg. should the timing jump big time when i open the throttle??? its prob around a 10 deg. jump

 

I've never checked it revved up, but I've heard others with more experience on the later 3rd gens claim there is a single "step" of advance that kicks in at a certain RPM (2500?) even with the ECM out of the equation. Like it's built into the electronics of the module itself.

If you find that to be the case, then it sounds normal. Certainly 10* is more than even the worst timing chain slop could account for.

 

thank you