Adjustable Mechanical Advance
One of the most important features of the MSD Pro-Billet Distributors is the adjustable mechanical advance assembly. The mechanical advance, sometimes referred to as centrifugal advance, allows you to accurately and easily modify the advance curve to match your specific application. MSD engineers have spent many hours at the dyno controls and in our labs perfecting this great distributor feature. A variety of timing curves can be achieved simply by changing the advance springs and stop bushing. The stop bushing determines the amount of mechanical advance that can be achieved. Each distributor is equipped from the factory with the blue (21°) bushing installed with five other bushings included; Red allows 28°, Silver 25°, Green 23°, Purple 19° and Black for 18°. The springs determine the rate, or how fast the advance occurs. Each distributor comes with two heavy silver springs installed which give the curve the slowest advance rate. There are also two sets of springs with different tensions included; blue and light silver, which can be mixed and matched to achieve a variety of advance rates. The charts to the left illustrate the variety of ignition timing curves you can achieve by simply changing the springs and stop bushing.
The advance assembly is mounted on top of every MSD distributor. Each model is supplied with different advance springs and stop bushings so you can easily tune in a timing curve to match your engine and application.
MSD introduced the first aftermarket distributor crafted from a billet of 6061-T6 aluminum. These Pro-Billet Distributors are now available for most popular domestic V8s and several other popular engines. You’ll notice that there are several versions of distributors available. There are similarities across the distributor line, such as the upper ball bearing and seal design to guide the QPQ coated shaft or the non-magnetic pickup, but there are several lines available that fit different applications.
This pretty well covers all of our distributors, however this is our traditional distributor. This is our most popular distributor and they require an MSD Ignition Control such as a 6AL or 7AL-2 Ignition Control. The distributor has a 2-pin connector that plugs directly into an MSD Ignition. These distributors are available from AMC to the famous W-Chevy motor. They’re built for everything, from powerful street cars to racers. Some have vacuum advance while others may be locked out. The important thing to note is that an MSD Ignition Control is required and are identified by the 2-pin connector.
MSD offers a line of distributors called Ready-to-Run. The biggest visual difference is that the distributor has a 3-pin Weathertight connector. These distributors have a built-in ignition module, so an MSD Ignition Control is not required. They’re simple to drop in and connect with three wires (power, coil negative and ground) making them favorites for street rods and muscle cars.They also have a gray tach output wire to trigger a tach or even an aftermarket EFI system, such as the Atomic EFI. Plus, there is now an adjustable rev limiter!
Like the name implies, these Pro-Billet Distributors will require a crank trigger to fire the ignition. These distributors do only that, distribute the spark. There is no trigger mechanism and no advance. They are meant as high performance, racing distributors. They are easy to identify with the lack of wiring and their lower stance.
MSD also offers several distributors that are Pro-Billet designs, yet they’re suitable as performance replacements for OEM models. Examples include the popular Ford TFI used in Fox bodied Mustangs. These distributors feature increased strength and support, yet incorporate the factory style module, pickup and connectors for a drop-in replacement.
MSD offers a high quality, value based line of distributors called Street Fire. Street Fire distributors are new distributors based around a cast aluminum housing and built to deliver performance at a value based price.