Introduced in 1962, Ford's Windsor small block is perhaps second in popularity and production numbers to the Chevrolet small block. While the Windsor block was also offered in 351-cubic-inch configuration (to compete dimensionally with the Chevrolet 350), 302 remains this engine's flagship displacement. What the 302 lacks in size it makes up for in top-end power and a broad torque band that worked well in typically-lighter Ford automobiles.
Base 2V (two-barrel carburettor) engines use single-point vacuum-advance distributors, and are factory-set to 6 degrees before top dead centre (BTDC). Set dwell at -4.44 to -1.66 degrees Cor manual transmission cars and -3.33 to -0.555 degrees Cor automatics.
1968 4V Engines
Higher performing 4V (four-barrel carburettor) engines also use single-point, vacuum advance distributors factory-set to 6 degrees BTDC, but vary on dwell time. 1968 IMCO (improved combustion) engines used bespoke distributors factory-set to 26 to 31 degrees dwell. Other engines that used the Thermactor emissions system required -4.44 to -1.66 degrees C dwell.
1969-71 4V Engines
All 4V engines were factory-set with 16 degrees of ignition advance and 30 to 33 degrees of dwell.
Other Carbureted Engines
1974 and later carburetted engines use electronically controlled, Hall effect-driven distributors in place of the points-type distributors used before. This eliminates a number of maintenance conditions, including dwell. Factory timing for most carburetted/non-points engines is between 6 and 8 degrees BTDC, but 10 to 12 is generally acceptable if you use high-octane gasoline.
Fuel Injected "5.0" Engines
During the early 1980s, Ford re-dubbed the 302 engine "5.0-liter" in a bid to modernise its image and draw a distinction between its new fuel-injected engines and older carburetted units. Almost all fuel-injected 5.0s (pronounced "five-ohs") come factory set with 10 degrees of timing BTDC, but the car's computer could vary timing several degrees in either direction to compensate for bad fuel, high altitude or engine malfunction. Many 5.0s can tolerate a few extra degrees of timing advance -- about 14 degrees on 91-octane fuel and as much as 16 degrees with 93 octane. Modern "Modular" 5.0 engines don't use distributors at all; the car's computer dictates and optimises ignition advance using sensor input.