26. Now I hope you followed me on the total timing because this is where it may get a little confusing to some people. On the underside of the MSD distributor there is a small, black bushing. This bushing can be swapped to a different size to switch the amount of advance that the mechanical advance can travel. Example: Installing a bigger black bushing will limit the amount of mechanical advance travel to 18 degrees total advance from initial timing. You can look at it like this, if we set the total mechanical advance to 35 degrees we could play with the amount of travel from initial timing with bushings. For instance, 35 degrees total equals 17 initial with black bushing, 35 degrees total equals 14 initial with blue bushing, 35 degrees total equals 10 initial with silver bushing, and 35 degrees total equals 7 initial with red bushing. Initial timing is the timing while the engine is idling.