1972 Mustang

There were quite a few changes made to the 351 CID High Performance engines made during the year of 1972. We have compiled the best information possible from multiple sources. We welcome DOCUMENTED factory information that can solidify the actual specifications.

1972 Q-code (351 Cobra-Jet)
The Q-code 351 “Cobra-Jet” (also called 351-CJ, 351-4V) was produced from May 1971 through the 1974 model year. It was a lower-compression design that included the open-chamber  heads. These open-chamber heads exhibited superior emissions characteristics and were required to meet the more stringent emissions standards for 1972 and beyond. The “351 CJ” high-performance engine included a different intake manifold, high-lift, long-duration camshaft with hydraulic valve lifters, different valve springs and dampers, a 750-CFM spread-bore 4300-D Motorcraft carburetor, dual-point distributor (with four-speed manual transmissions only), and four-bolt main bearing caps.

For the 1972 model year, the only change to the engine was a retarding the camshaft events by 4°. The engine was rated at 266 HP SAE Net for 1972 when installed in the Mustang, and 248 HP in the Ford Torino and Mercury Montego.

1972 R-code (351 HO)
The 351C HO “R-code” had a number of changes to help meet emission standards for 1972 compared to the 1971 Boss 351 “R-Code”. The camshaft had less duration, but more valve lift, while the mechanical lifters remained unchanged. The forged pistons were changed to flat-top style and the heads to open chamber heads, but retained the same large ports, valves, and adjustable valve train used in 1971. This resulted in a compression ratio decreased to 9.2:1 while the cleaner-burning open-chamber heads helped meet the new emissions regulations. The Ram Air option was no longer available. The engine otherwise remained unchanged from 1971. This engine produced 275 HP using the  SAE net system and was only available in the 1972 Ford Mustang

In 1972, Ford Mustang production totaled 125,813 units, with models including hardtops, SportsRoofs, convertibles, Grandé, and Mach 1, offered in 16 colors, including two new Color Glow exterior paints. Four engine options were available, with the 302 Windsor as the base engine for the Mach 1, and the 351 Cleveland offering a 2-barrel, 4-barrel, and the new R-code 351HO. 

Production Numbers:

• Total Production: 125,813
• Convertible: 6,121
• Fastback: 16,622
• Fastback, Mach 1: 27,675 

Body Styles:

• 2-door hardtop
• 2-door fastback
• 2-door convertible
• SportsRoof
• Grandé
• Mach 1 

Engines:

• Base Engine (Mach 1): 302 Windsor 
• 351 Cleveland Options:
  • 2-barrel 
  • 4-barrel 351CJ 
  • R-code 351HO (lower compression Boss 351) 
• Other Engines:
  • Four engines in total 
  • The Boss 351 and both versions of the 429 engine were dropped 
  • During the early part of ’72, a special 351HO model was offered