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A History of the Ford 429ci V8, The Blue Oval's Final Big Block Muscle Car Blast

Ford big block V8 engines never quite hit the same pop culture status as those built by General Motors or Chrysler during the original muscle car era. Whether it was because the small block 289 and 302 were stealing the thunder in the Mustang, or because the Beach Boys never wrote a song about one of them, Ford's largest engines typically kept a low profile unless they found their way under the hood of its previously-mentioned pony car. It also didn't help that the automaker had several competing families of big blocks to contend with throughout the '60s and into the early '70s, which made it harder for any one of them to achieve critical mass on the street.

Boss 429 engine

Before EPA pollution controls and the energy crisis restricted big block V8s to lazy-revving, torque-happy drivetrains for trucks and luxo-barges, the Blue Oval managed to churn out one last tour-de-force for the straight-line crowd. The Ford 429 was the final hammer in the classic Mustang's toolbox, and it also pounded nails for a handful of other models before it was retired by the energy crisis reality that squelched the cubic inch craze.

Versatile Sledge-Hammer

Ford's new 385-series V8 engines first appeared in 1968. It was a two-birds-with-one-stone effort, as the 385 designs eventually replaced not just the common FE engines found in trucks, passenger cars, and performance machines, but also the less-common MEL (Mercury-Edsel-Lincoln) motors offered by the company's luxury divisions.

Mustang 429 at Bonneville

Of these new big blocks, the most versatile was the 429 cubic inch version. Ford initially found a home for the 429 in the recently redesigned Thunderbird (which had transitioned into a coupe and sedan combo the year before), but it wasn't long before the engine was offered in the brand's full-size cars (such as the LTD), mid-size models (the Torino and Ranchero), as well as F-Series pickups and commercial trucks.

Ford Torino with Cobra Jet

The engine, which offered a 4.36 inch bore and a 3.59 inch stroke, offered slightly less displacement than the 460 cubic inch motor from the same 385 family (which was named after the latter's 3.85 inch stroke), and at first it was also more modest in its output. The thin-walled design weighed almost 100 lbs less than the 460, however, which made it a logical choice when it came time to build a performance version of the new big block.


The 429 was well suited to a competition role thanks to its sizable bearings and semi-hemi combustion chamber (with angled valves canted into the head that allowed for a larger size), and even out of the box its advertised (read: underrated) 360hp made it a strong street contender.

Here's what happens when you put a 10.51 cr 429 cid V8 in a Mustang Boss 429!

To make it a match for circle track NASCAR and straight-line NHRA racing, Ford created the 'Boss 429.' This unit offered an aluminum head, better oiling, four bolt mains on the block, improved hemispherical combustion chambers (with large squish areas that kept them from being 'true' hemis), and a massive 1000 cfm 'Dominator' carburetor from Holley.

Mustang 429 on Nittos

The street version of the Boss 429 found its way into the Boss Mustang so that Ford could homologate the engine. Although it used a less-generous carb setup, Ford still rated the Boss 429 at 375hp and 450 lb-ft of torque—again, figures that are considered conservative (by nearly 100 ponies). Built in extremely low numbers, less than 1,400 examples were sold in 1969 and 1970.

Cobra Under Your Hood

The 429 didn't just star in the Boss. A Cobra Jet version of the motor intended for street, rather than track, was also offered starting in 1970, and it could be had in the Mustang as well as Ford's 'intermediate' cars like the Torino. Rather than re-engineer the stock head completely, the 429 Cobra Jet simply offered larger valves and ports, a higher compression ratio (11.3:1), and a number of other hardware upgrades to support an advertised 370hp rating (along with the ubiquitous 450 lb-ft of torque).

Mustang Boss 420 in courtyard

The CJ, as it was known, was available as a relatively inexpensive upgrade, and if you were willing to spring for the right axle ratio you could also opt for the Super Cobra Jet the following year. Like the Boss 429, the Super Cobra Jet provided four bolt mains, a larger carb, an oil cooler, forged aluminum pistons, and a more robust oil pump. Hoodwinking an insurance industry that was increasingly terrified of these land missiles ending up in the hands of teenagers, Ford claimed a mere five horsepower improvement with the Super CJ over the base CJ.

A Glimmer Of Glory

As with the Boss 429, both the Cobra Jet and the Super Cobra Jet enjoyed too short a season. By 1973 each of these phenomenal engine options had been removed from the order sheet, with Ford's largest cars making do with the 460 cubic inch 385-series motor (albeit in detuned form). The latter lasted almost until the new millennium in the Super Duty pickup line before being replaced by the brand's modular motor architecture.

Boss 429 engine in Mustang

The Ford 429 saw a surge in popularity among drag racers in the early '80s due to NHRA rule changes, and while the Boss remains far too valuable to carve up in a restomod, the Cobra Jet and Super Cobra Jet are still a good choice for modern builders seeking a unique and powerful hot rod platform. It's even possible to drop in a 460, four-bolt block in place of the original Super CJ and achieve the same results. The aftermarket is full of better breathing choices for 429 intakes, and with existing balance, blueprinting, and porting technologies it's possible to squeeze at least an extra 100 horsepower out of the CJ family compared to the original factory rating.

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