If you’ve ever removed the cap and rotor from a high mileage HEI distributor, underneath the rotor you are likely to find the entire mechanical advance system covered in a red oxide dust.

Davis Unified Ignition (DUI) install In An AMC 304 Four Wheeler's Verne Simons installs a ignition system known as HEI or high energy ignition by Davis Unified Ignition in an AMC 304. Related Videos ...