How do you advance the timing on a Ford 302?

Loosen the distributor hold down first. On most distributors turning clockwise will advance timing, CCW will retard timing. For V8s I like to set the timing like this:

Advance timing a bit, then grab the throttle on the carb and rev the engine to full throttle. Keep repeating these 2 steps until the engine stumbles or pings when you rev it up. When you get to that point set the timing back just a touch, and rev it again to make sure you are at the point just before where it wants to stumble.