Quote Originally Posted by rboltz View Post
Not sure I understand this but what I think this means is you set something on the light for 5 degrees advance and then adjust for "0" as the light delays the trigger by 5 degrees?
That's it.

On the back of the light, there is a dial, or with the digital ones, an up and down button.

You can set this dial to say 5 or 10 degrees and then when you adjust the distributor, your target is the zero mark. Works well on cars that don't have the degrees marked off, and for checking total advance. Just a nice little convenience.