Throwback Thursday: 1969 Boss 429 Mustang

The Boss 429 is sort of a holy-grail of Sixties muscle cars, with only 859 produced in its two-year run. Its origins came from Ford’s efforts to develop a hemi-head engine to go up against Chrysler’s 426 Hemi on NASCAR tracks. NASCAR rules of the day mandated that at least 500 cars with any specific competition engine had to be marketed to the public, and it was decided that the Mustang would be the car for the 429.

Ford hired the Dearborn shop of Kar Kraft to take on the project, modifying 428 Cobra Jet and Mach 1 mustangs to accept the monster engine. Kar Kraft widened the shock towers, modified the front fender wells, altered the front suspension mounts, reposition ed the battery to the trunk, added a manually-opened hood scoop and made other fairly radical changes to the Mustang engine well. The final product was rated at 375 horsepower, although actual output was likely well over the 500-horsepower mark; the lower rating was to keep drivers from being stuck with stiff insurance rates.

The Boss 429 featured a toned-down appearance, with only a NASCAR badge and Boss 429 graphics to differentiate it from its tamer brethren, although it was available in colors like Grabber Orange, Calypso Coral, Candyapple Red and Black Jade.

Surprisingly, the Boss 429’s performance was on a par with the 428 Cobra Jet of the time: standing ¼ mile in 14.09 seconds, 0-60 in 7.1 seconds, top speed of 118 mph, although the potential was there for easy bolt-on mods to really bring out the best in the 429. Today, however, these cars can easily bring $400,000 at auction.

Think that’s rare? Factory records also indicate that two (!) Boss 429 Mercury Cougars were built, and that two Boss 429’s were equipped from the factory with three two-barrel carburetors!

1969 Boss 429 Mustang Tires: