Tuning

You don’t need an 02 sensor. They help but it’s not a mandatory item. If you elect to get an 02 sensor, AEM has good stuff.

A dial back timing light is just that. It has a dial that you twist to adjust the light. So when you want 10-15 or 20 degrees advance on the inital timing and a standard light flashes, where does the timing mark go? The dial back will see it when you twist the dial to 20*’s.