Racing classes that require locked timing need the centrifugal advance gone, not just limited. This plate takes the place of the mechanical advance weights and slides over the pins on the distributor shaft, so total timing no longer changes with rpm. It is the same part fitted to the Circle Track HEI distributor from the factory.

MSD 88363 Mechanical Advance Lockout Plate Features:

• Replaces the mechanical advance weights to eliminate centrifugal advance.
• Slides over the existing pins on the distributor shaft.
• Works on most GM HEI distributors.
• Standard equipment on the Circle Track HEI distributor.
• Will not work on Pro-Billet HEI distributors.