Hah I wish the 92 was 16. I'm 12 city and 15 highway

 

What exactly would bumping th timing do? How do you do it yourself?

 

Get a timing light. Unplug the SPOUT connector, connect timing light to battery and the #1 plug wire. Sqeeze trigger on timing light with truck running, notice the light "strobes". Point it at the harmonic balancer on the front of the crank. Probably can't read a damn thing. So stop. Turn truck off. Clean up harmonic balancer/pulley with a scotchbrite pad so you can read the timing marks. Restart motor, repoint light at pulley. Read the timing. IIRC 10* BTDC is stock. If its at 10*, loosen the distributor hold down bolt, turn the distributor ever so slightly (clockwise). Tighten hold down, recheck timing. If its at 11 or 12*, go for a drive after plugging the SPOUT connector back in. No radio. Listen closely for engine knock, especially under hard load. Some trucks will run at 15* BTDC, whereas my 96' will knock at 12* and up, you don't want that. If it knocks, retard the timing a bit. Takes a little trial and error, but really isn't tough at all.

Advancing the ignition timing will improve combustion, and efficiency. It makes the "explosion" begin earlier. If you go too far, the ignition of the air/fuel mix happens too early (pre ignition), and could theoretically reach the point of trying to reverse the rotation of the motor...NOT GOOD. You ideally have the flame front/pressure wave of the "explosion" hit the top of the piston right after the piston is at top dead center (TDC), so all the force goes into driving the piston down, turning the crank. Generally helps higher RPM power. You can bump valve timing too, that will help low end grunt, but is more involved than ignition timing.

Here's a link to a Youtube vid about ignition timing. They're working with a 350 Chev, so some things are different, but they explain things pretty well. How to set your ignition timing - YouTube