To set the ignition timing on a Ford 5.8 L engine, remove the in-line spout connector, loosen the distributor bolt, connect the timing wires to the battery, and then set the harmonic balancer to align with the timing mark. The Check Engine light may come on when doing this; clear it by unplugging the negative battery cable for about 10 seconds.
Remove the in-line spout connector by pulling it with one hand while holding the electrical connector with the other. Look at the timing light, and if it does not have an adjustable advance feature, mark the harmonic balancer housing at 10 degrees. Loosen the bolt that holds the distributor hold down clamp, and then connect the positive and negative wires from the timing light to the truck's battery. Connect the spark plug adapter to the first spark plug wire, as this is how the timing light receives the signal.
If the timing light has an ignition advance feature, set the dial to the 10-degree mark, and make sure the zero mark on the harmonic balancer aligns with the timing mark on the engine. Also, make sure that all the wires are away from all fans and belts. Also, be careful when moving the distributor, as loose clothing may catch on the fan or belts, too. When complete, remove the timing light, tighten the clamp that holds the distributor, and then turn the in-line spout on.