The birth of the Cobra Jet engine package from Ford was in response to external pressures. Competition was tough in the late '60s, with both GM and Chrysler offering up serious big-block performance. Success at the track meant success at the dealership, and Ford knew this. Sales success of the Mustang had been phenomenal in its first two years, and Ford wanted more. However, the original Mustang platform, as popular as it was, could not accept the larger engines Ford already had in its product lineup, because the engine compartment was simply too small. This was remedied by the introduction of the all-new '67 Mustang.
Although the '67 Mustang looked a lot like the original, it was, in fact, a completely new car with no interchangeable sheetmetal. The new Mustang was beautiful, and it had a large enough engine bay to take the big mill. For Ford, this meant the venerable FE-series big-blocks, which had seen successful service in the Thunderbird as well as other car lines.
All this was none too soon. In fact, Ford had seen the writing on the wall. The company was aware of the new Camaro project brewing over at Chevrolet. The Mustang now had company in the ponycar market, and the new Camaro was no slouch. It was a good-looking car featuring wide availability in its engine selection. When the Camaro hit the streets with a 396ci engine borrowed from the Chevelle parts bin, Ford knew it had competition.
The 396 was a durable and slightly detuned racing engine that ran very hard. It was available in the new Camaro in 325-, 350-, and 375hp forms (a 425hp version had been available in the Corvette for '65). The 396 was known in Bow Tie circles as the Mark IV and was further known as the "mystery motor" because it was developed in secret for the '64 Daytona 500. The 396 featured advanced-design, canted-valve cylinder heads that flowed like crazy and earned the name "porcupine" because of their splayed-valve arrangement. A whole host of high-performance parts was available for the 396 from the Corvette larder, which further complicated matters in Dearborn.
Ford was not caught in flagrante delecto, however. Ford countered by introducing the FE-series 390ci V-8 engine for the '67 Mustang. The 390 big-block version of the Mustang ran fairly well--well enough to post mid-15-second times in the quarter-mile. This was not enough to beat the big-block Camaro, however, which ran the quarter a full second quicker. In the quarter-mile, a one-second difference is a lot of car lengths.
Chevrolet wasn't Ford's only problem in the performance department. Pontiac had its GTO as well as the new twin sister to the Camaro, the Firebird, and each was available with a 400ci engine. Chrysler had the 440ci RB wedge engine, not to mention the brutal 426ci hemispherical head motor known as the Hemi. But it was the Camaro-Firebird that joined the Mustang in the ponycar class. This became a private war between the automakers. The stage was set, and war was waged in earnest.
Although the 390 had been offered in the Mustang, the FE had seen incarnations of up to 428 ci. In 1963, the 427 saw service in a series of lightweight Galaxies, which had seen some racing success despite their weight.
In 1964, the 427 was shoehorned into the Fairlane, Ford's midsized entry, between the Galaxie on the big end and the Falcon on the small. Known as the Thunderbolt, this Fairlane saw very limited production and was built as a factory lightweight race car. The Thunderbolt proved to be a very fast factory team drag racer--and proved again that the FE engine could be a formidable competitor. These cars ran the quarter-mile in the mid-11-second range, quick by any standard.
The big FE also became notorious as one of the powerplants for Carroll Shelby's outrageous big-block-powered version of the AC Cobra. The problem with the 427 was that it was far too expensive to produce for use in a regular production car. This explains why Ford went with the 390 in the Mustang instead of the 427. As we all understand, the 390 wasn't standing up to the 396, and sales reflected this.
A remedy was in the making, as the 428 Cobra Jet package for the Mustang began its metamorphosis. Carroll Shelby, famous for his GT350 version of the Mustang as well as for the Cobra, became involved when he decided to produce a big-block version of his Shelby Mustang GT series. Ford had produced a 428ci version of the FE engine for fleet use in police cars and also for some of the fullsize luxury cars.
Shelby realized that this was a real alternative to the expensive and temperamental 427. Slightly smaller in bore but longer in stroke, the 428 ran smoothly in street trim, but it was still a very powerful engine, with mountains of torque. When this 428ci engine was installed in the Mustang, Shelby called the car the GT500. All of this was a step in the right direction, but the '67 GT500 was still slower than the rip-snortin' 375hp 396 Camaro. Everyone at Ford was confounded, and the brass didn't want to go back to the 427 because of the high cost of its heavy-duty internal components.
Enter Bob Tasca, a Ford dealer who had a history of experimenting with Ford big-blocks for his dealership-sponsored race cars. He had been involved in the Thunderbolt program back in 1964. His cars had been very successful, and word on the street was Tasca's cars were working very well. Ford execs got the word. Tasca had bolted 427 Low Riser cylinder heads on the 428, which really woke up this mill and gave it much better breathing capability while retaining the low-end torque the big FE was already noted for. The big-block Chevy had the edge in breathing ability, but this move closed the gap between the two engines a great deal. According to the excellent Boss and Cobra Jet Mustangs by Dr. John Craft, this is how the Cobra Jet was born.
Ford got down to business and began by beefing up the bottom of the 428 block casting, which included heavier main bearing caps. An improved crank and rods were also part of the deal. A fairly mild hydraulic cam combined with the good-guy Low Riser cylinder heads made for an engine with a flat torque curve and good horsepower numbers. The factory ratings were intentionally low for insurance reasons. In fact, the 428 was listed at 335 hp, the same as the 390. Actually, about 400 hp were on tap in this incarnation of the 428. With a few minor modifications, however, the 428 would really scream, and by the time the '68s came around, Ford was ready to rock and roll.
At the '68 NHRA Winternationals in Pomona, California, Ford entered a number of specially warmed-up '68 Cobra Jet Mustangs. The cars ran very well and won in the Super Stock category that year. This victory was not lost on anyone--the public, the press, and Ford alike--much less the competition. Although these cars were slightly different than what would shortly be on the showroom floor, word was out that the Cobra Jet package was the way to go. In April of 1968, when the Cobra Jet Mustang hit the showroom floor, it sold like blueberry pancakes.
Included in any Cobra Jet package was a choice of the durable Top Loader four-speed transmission or a heavy-duty C6 three-speed Cruise-O-Matic, and of course the famously sturdy 9-inch rearend. When the buyer selected the CJ option, the GT option became mandatory. Originally available in any of the three Mustang body styles--coupe, fastback, or convertible--all '68 CJ Mustangs are highly sought after, even 30 years later.
Needless to say, the success of the Cobra Jet package guaranteed its reappearance for the '69 model year. Although the Mustang had been completely redone, little changed in the CJ engine for 1969, and it was still available in any type of Mustang. The package was also available in the Torino, the Fairlane, and the Mercury Cyclone.
In 1969, 10 different Mustang engine options were available. A special option available for 1969 in the Cobra Jet Mustang included a 428 with internal modifications. Whenever a differential with a gear ratio of 3.91:1 or 4.30:1 was ordered as an "optional axle ratio" at a cost of $6.53, a lot more than just lower gears came with the package.
The car automatically became a Super Cobra Jet. The package included special capscrew-type connecting rods borrowed from the Ford GT Mark IV 427 Le Mans engine. A different crankshaft and forged-aluminum pistons were also included. Even an external oil cooler was part of the deal--not bad for $6.53. This package became notorious in slang as the Drag Pack. Also, 1969 was the last year of production for the famous Mustang GT. Very few were ordered because of the popularity of the new Mach 1 package. Because of this, '69 Mustang GTs are collectors' favorites.
Cobra Jet Mustang production continued into 1970. The '69-'70 Mustangs were nearly identical cars featuring minor cosmetic changes. Dr. Craft notes that one significant change for 1970 was the inclusion of a rear sway bar for Cobra Jet Mustangs.
Many aficionados of the Cobra Jet Mustang consider the '70 version to be the nicest of all, combining the last year of the FE engine with the last year for the '69-'70 body style. Nineteen-seventy was the last year for the venerable FE-series big-block engine in the Mustang and Cougar. Introduced in 1958 for service in fullsize Fords as well as the Thunderbird, the FE had seen a long and colorful career. In various incarnations ranging from 332 ci all the way up to the 428, the FE was the heart and soul of many winning Ford-powered automobiles. Besides the T-Bird, there were Galaxies, Thunderbolt Fairlanes, Mustangs, Torinos, and both the AC Cobra and GT 500 Shelbys.
For the '70 Torino and Cyclone and the '71 Mustang and Cougar, the passing of the 428 meant a switchover to the new 385-series Ford big-block. The 429ci Cobra Jet was a different entity entirely. The Mustang had grown bigger than ever, with a weight of nearly two tons. This was the year that stricter emissions laws went into effect, and emphasis was shifting away from performance. Compression ratios were lowered considerably, and with this, performance often went out the window.
Still, a '71 'Jet had a 0-60 time of 6.5 seconds and a quarter-mile time of 14.1 seconds, so it was no snail. But times were changing, and sales were soft for performance cars across the board, and not just at Ford. Sadly, Ford discontinued the 429 Cobra Jet Mustang and other CJ-powered cars halfway through 1971.
In four years of its existence, the Cobra Jet name became synonymous with high-performance. Introduced at the height of the high-performance wars, big-block Cobra Jets acquitted themselves well in the Mustang and in other cars. The name is perhaps one of Ford's most enduring performance legacies. It is remembered by those who love the Ford Blue Oval, and feared by others who would challenge the cars bearing the Cobra Jet name.