[justin4260]

heres an old mechanics trick my grandpa taught me about timing. drive the truck till about 30-45 MPH (just after it switches to gears) coast for a short distance and then accelerate quickly about 5 mph giving the engine load. if you hear pre ignition knock (sounds kind of like marbles in the engine) retard the timing a little bit and the entry again. if you don't hear a knock advance it little bit. retest till you hear the knock and the back it off just slightly. that will set your low end timing but for the high rpm advance you need to play with the springs and weights underneath the distributer cap. heavier weight/ lighter spring = timing advanced quicker. lighter weigh/ heavier spring = timing advance later on.