Why Ford Mustang Fans Are Still Salty The Boss 351 Beat the 429 Cobra Jet in 1971 – Jalopnik

A single test drive can enhance or tarnish a car’s legacy. Sometimes the damage is well deserved, for example when a car cannot meet expectations. You just have to scan Car and driver test of Jerry Wiegert’s constantly breaking Vector W8 to understand that level of disappointment (although Wiegert was probably even more disappointed when then-Lamborghini owner Megatech forced him out of his company). What’s even more frustrating is when the test forever tarnishes a car’s reputation, while the details are ignored even though they change the whole picture. Such is the case with a comparison from 1971 Motor trend of three Mustangs: a Boss 351, a 429 Cobra Jet-powered Mach 1 and a standard hardtop with a 302.

Let’s ignore the base Mustang and focus on the Boss 351 and 429 Cobra Jet. In the acceleration tests, the 429CJ lost. Despite making 370 hp and 450 pound-feet of torque compared to the Boss 351’s 330 hp and 370 lb-ft, the 429 CJ lagged behind on every metric. The Boss 351 sprinted to 60 in 5.8 seconds, while the 429CJ needed 6.5. The quarter mile was even more embarrassing, as the Boss breezed through it in 13.8 seconds at 107 mph, while the 429 recorded a relatively lazy 14.61 seconds at 96.8 mph.

Taken in a vacuum, this may seem like the 429 had inflated power numbers or that the 351 was stronger than advertised, but that doesn’t explain literally everything else. The Boss 351 had a final drive of 3.91:1, while the 429CJ Mach 1 had a ratio of 3.25:1. Only the Boss had a four-speed manual transmission, while the 429CJ was saddled with a Cruise-O-Matic three-speed slushbox. Motor Trend’s 429CJ also had air conditioning, a power parasite not found in the Boss 351. In other words, it wasn’t a fair fight.

Were there period tests other than Motor Trend’s? Yes, and they were also unflattering on the surface, but telling in the details. Graphic sports car tested a ’71 429 Cobra Jet Mustang and also achieved a 14.6-second quarter, this time with a four-speed manual transmission. However, the tires were F70-14s, which have a tread width of only 6.7 inches. Moreover, the difference was still quite large: 3.50:1. However, the pedaling speed was 150 km/h versus that of Motor Trend 96, indicating that the Sports Car Graphic car accelerated faster and faster, probably after the narrow tires grabbed and stopped producing more smoke than thrust.

A test that may more accurately represent the 429CJ’s growl is the one found in Super stock magazine. That test achieved a quarter of 13.97 seconds at 100 mph, and the Super Stock car had an automatic and air conditioning. No gear ratio is mentioned, but the 429CJ ‘Stang ran on 8.4-inch-wide G60-15s, which perhaps offered a little more traction than the F60s on Motor Trend’s car.

What’s frustrating is that period tests for the 429 Super Cobra Jet don’t seem to exist. Supercars ’71 tested a Cobra Jet that had at least a 4.11:1 gear ratio, and despite the handicap of the automatic transmission and riding on 6.4 inch wide E70-14s, it ran a quarter of 13.4 seconds at 107 mph. Imagine if it had wider tires! Apparently it was a 429CJ with a custom Detroit Locker rear end.

Meanwhile, most Boss 351 tests show quarter-mile times under 14 seconds. But it is striking that almost all tests used prepared or modified cars. The Motor Trend car had aftermarket headers. Hot Rod and Car Craft’s Boss had headers and a disconnected rev limiter. The popular Hot Rodding’s Boss had headers and tie rods. Only Car and Driver’s Boss 351 appeared in stock, and even then magazines were known to give top marks regardless of what actual showroom vehicles would achieve. In addition, testing procedures were less rigorous or standardized back then.

The point is: Mustang fans deserve to be salty. Even now, 55 years later, the ripple effects are being felt in the values ​​of 1971 Ford Mustang Boss 351s versus 429CJ Mach 1s. Boss 351s are consistently worth thousands of dollars more. And forums still have users saying that magazine tests showed the 429 was slower. Man, Rodney Dangerfield got more respect.