Advance Lockout Plate - GM HEI Dist.

The PROFORM Advance Lockout Plate for GM HEI Distributors is a precision vacuum advance control component engineered to disable or regulate vacuum advance function in High Energy Ignition (HEI) distributor systems. This plastic lockout plate is designed specifically for GM HEI distributor applications where vacuum advance timing control must be managed during engine tuning, performance calibration, or dyno testing.

The vacuum advance lockout mechanism operates by physically blocking or isolating the vacuum signal port on the distributor, preventing atmospheric pressure changes from automatically advancing or retarding ignition timing. This allows engine builders and tuners to establish a fixed ignition curve during initial diagnostics or when transitioning to alternative ignition control systems. The compact molded plastic construction weighs just 0.08 lbs and measures 4.6 x 1.1 x 7.05 inches, making it a straightforward bolt-in replacement or supplemental component for HEI-equipped engines.

This component is essential for GM engine swap projects, carburetor-to-fuel-injection conversions, and custom ignition system installations where OEM vacuum advance behavior must be eliminated or isolated. Technicians and restoration specialists working with classic and modern GM V8, V6, and inline-6 engines often install this plate when moving to programmable EFI systems or mechanical advance-only setups, ensuring ignition timing remains independent of intake manifold vacuum signals during the transition period.

The PROFORM brand carries decades of proven reputation in performance fuel systems and ignition controls, and this lockout plate reflects that engineering heritage with reliable material selection and correct fitment geometry for GM HEI distributors across multiple engine generations and displacements.