The letters C and J take on new meaning in 1971: BEWARE

The letter C in the VIN number stood for the Non Ram-Air version of the 429 Cobra Jet, and the letter J stood for the Ram-Air version. Either way, you were looking at an engine rated at 370HP and 450Lbs/Ft of torque. And you could get these engines in any body style available so long as you didn’t have to have AC. Here is how the Cougar Club of America describes the '71 429 Cobra Jet option.

The 429CJ option was available for the 1971 model year only. There were 448 cars built, 47 convertibles and 401 hardtops. To date (3/01) we have 36 cars registered, 13 convertibles and 23 hardtops.

The 429CJ option was offered in two guises, J-CODE = RAM-AIR and C-CODE = NON-RAM AIR, horsepower and torque figures were quoted the same for both options: 370HP and 450FT/LBS. The 429-Cobra-Jet Registry was established to document and track all 429CJ optioned Cougars.

C or J in VIN
All models and body styles were available with the 429CJ option including XR7/STD convertibles and hardtops and the Cougar GT.
All cars featured a dress up engine kit featuring “Ribbed” aluminum valve covers, bright dipstick, oil filler cap, radiator cap and air cleaner cover. NOTE: bright air cleaner cover available on non ram-air equipped cars only.
All engines featured 4 bolt main bearing blocks.
Hurst 4speed or C6 automatic transmissions were required options (no 3 speeds). All 4 speed cars have rev limiters, C6 transmissions were a special unit with additional clutch plates, cast iron tail-shaft and “R” servo.
All cars had competition suspension. Larger front sway bar, rear sway bar, heavy duty shocks, staggered in the rear.
Power steering equipped cars had variable ratio 20.2:1 and a power steering cooler on 3:50 rear end ratio cars only. (power steering oil cooler were included on some but not all 3:25 rear end ratio cars.
Power brakes were a required option.
All cars were equipped with 27" heavy duty radiators.
All cars were equipped with a 720CFM Rochester/Quadrajet carb. ( Note the 780 Super Cobra-Jet was not offered as a production option.
“Drag pak” and “Super Drag pak” were not offered as production options.
Functional hood scoop was a feature of the Ram-Air option, all Cougar GT models have hood scoops but functional only on 429 Ram-Air motor option.
All cars were equipped with dual exhaust.
All cars were equipped with heavy duty battery (Group 27F).
Rear end ratios were 3:25 or 3:50 only, traction lock was optional. All air conditioned cars required the 3:25 ratio. All cars had 31 spline rear axles.
Air conditioning was not offered as a production option on convertibles.
Tire/wheel options were 14x7 with either F70X14 or F70X14RWL traction tires. 15X7 wheels with hub cap and trim ring and F60X15RWL traction tires were an option.
All paint and interior codes were available.


Just to be clear those that wanted a drop top - had to give up the a/c, it was available with a hardtop.

The reason was weight - The combo of A/C, C6 and a Conv would have reqired larger tires, which would have caused a wheel well clearance problem.

Mitch Lewis
429CJ Registrar

Hey Mitch! Welcome!

Thanks for the clarification, and of course, you are correct. I’m still learning after all of these years.

The other item of note with a/c - it was available with 4spd and track-loc rear ends or both. You were restricted to 3.25:1 gears. The 429 utilized an underdrive pully to limit the potential of overreving the compressor.

Also, one other interesting item of note for 1971 429CJ Cougar. You could NOT get a 429 Super Cobra Jet in a Cougar. Only the 429CJ. No Holley carb. No drag pak option (no oil cooler, etc.). Not sure why Mercury did that…

In 71 Only the Mustang offered the SCJ, No Torino, No Cyclone either!