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The 1971 Boss 351 Mustang Signaled The End Of The Golden Age Of Muscle Cars

How Much Power Did The 351 Cleveland V-8 Make In The 1971 Mustang Boss?

The 1971 Mustang Boss 351 was one of Ford’s last true muscle cars, and they only churned out 1,806 of them in their single year of production. This was one of Ford’s hottest-performing small-block cars, and it was all thanks to the R-code V-8 351 Cleveland under the hood. It spat out 330 hp at 5,400 rpm and 370 lb-ft of twist at 4,000 rpm—more than enough to slap around many big-blocks.

In fact, the performance of the Boss 351 was only a tick under the previous Boss 429 Mustang! Sure, the 1969 BOSS 302 (which duked it out with Camaro Z/28s in Trans Am racing) and the 1969 Boss 429 (which was built so Ford could field the big-block in NASCAR) were cool, but Ford’s departure from racing along with the aforementioned emissions requirements killed those cars in 1970, and began the automotive slide into malaise. Mustang sales, which had once reached well over half a million, slumped to under 200,000.

How Many Years Was The Mustang Boss 351 Produced?

But there was a bright spot for 1971: the Boss 351! Built on an all-new, larger and heavier body (which lasted through 1973 and the introduction of the Mustang II), the new Mustang was targeted towards the Mustang’s maturing customer base, so while the engine bay was bigger to more easily hold big-blocks, the interior was also larger for families.

Of course, the Boss 351 Mustang was about more than just a badass engine. There was also the four-speed Toploader manual trans with Hurst shifter, and heavy-duty Competition Suspension package with larger front disc brakes. The only option for the rear was a Traction-Lok 9-inch with 3.91 gears, but the transmission was available in both wide- and close-ratios. With either one, the Mustang buzzed along at 3,200 rpm while doing 55 mph on the highway.

Was The 1971 Mustang Boss 351 Considered A Fast Car?

The exterior of the Boss 351 was given special attention as well, from the twin functional NACA hood ducts to the Mach 1 honeycomb grille and unique bodyside stripes, and the hoods and graphics were done in either black or argent depending on the base color of the Mustang. Motor Trend tested the car in 1971, and it ran 13.8 seconds in the quarter-mile. HOT ROD Magazine took a look at the Boss 351 in the February 1971 issue and stated, “This one feels like it’s taking on the size of a Torino (and in some ways, it is), but no matter what its shape or size may resemble, it sure looks like a racer.

The Boss 351 is going to salt away a few Z/28s before its season is up.” The big car was made fast by the stout 351 V-8 under the hood. Filled with a nodular-iron cast crank, four-bolt mains, forged rods with 3/8-inch bolts, and aluminum pistons, along with high-flowing 4V heads that helped the 351 punch outside of its weight class. It also fielded a soon-to-be-rare high compression ratio of 11.7:1. The carb for the 351 Boss was an Autolite 4300-D, which was made specifically—and only—for the Boss 351. To say they are rare is an understatement, with examples fetching thousands of dollars, if you can find one.

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