Steve Davis is the founder of Memphis Distributors. Also known as DUI or Davis Unitized ignitions. I found the article by David Vizzard interesting and informative. But I don't agree with all observations and tips recommended. If a Vacuum advance can is so great why aren't they used on Magneto applications? Also a Pontiac 455 with 1970 RAM AIR 4 Heads require only 32 degree BTDC total timing with 100 octanr leaded gas. 110 leaded 36 BTDC. Pontiac 6X smog era heads same timing total for peak power unleaded or leaded gas.