History

• The Boss 429 was a project designed to enhance Ford's racing team. At that time, NASCAR required that 500 units of any particular engine design were to be qualified in order for that engine to be used in racing. However, instead of putting the engines in the civilian version of the Torinos that were used in racing, Ford opted to install them in the restyled 1969 Mustang fastback.
  
  

Mechanical Features

• The Boss 429 was a serious engine. It featured a forged steel crankshaft, four-bolt mains, and staggered valve, big port aluminum heads with combustion chambers that were crescent-shaped. The carburetor was the impressive 735-cfm Holley four-barrel with ram-air, and the engine had header type exhaust manifolds and an aluminum high-riser. Neither an automatic transmission nor air conditioning were options in this dedicated muscle car
  
  

Production Numbers

• Unfortunately, the Ford factory racing program went by the wayside soon after the introduction of the Boss 429 Mustang and so only 1,356 Boss 429 Mustangs and two Cougars with the same engine were built in 1969 and 1970, making these rare and collectible vehicles.
  
  

Side Note

• The Boss 429 Mustang was most expensive non-Shelby Mustang both to build and at resale. Part of the cost was due to the extensive reworking of the front end and suspension to fit the 429. Surprisingly, this wider front track improved geometry and, when equipped with the larger tires, gave the Boss 429 great handling characteristics, an area that usually suffered when beefing up muscle cars.
  
  

Negatives

• The Boss 429 was designed for the super speedway and so high revs were needed instead of instant acceleration from a standing stop. In addition, the initial batch of these vehicles were fitted with incorrect valve springs and stopped winding at 4,500 rpm instead of the correct 6,000 rpm. The result was that this car, even when tinkered with and equipped with aftermarket drag racing equipment, could never compete in the quarter-mile runs.