I have a 1990 fullsize blazer with a tbi 350. Ive heard thta on the tbi engines, the timing was retarded for emissions, and it can be advanced for better mpg and hp. Has anyone experimented with this? How much should it be advanced? Im also putting 8 mm wires and a blaster coil on it this week.

 

i would check fullsizechevy.com they have more information on tbi since the s series ran differently. i checked it out a lot when i had my 87 k5. same set up as yours actually