BUYER'S GUIDE: 1968 FORD MUSTANG COBRA JET

For the 1967 model year, Ford first offered a big-block engine into the Mustang. The 390-cu.in. V-8 was now available, with 320 horsepower on tap. In conjunction with the refreshed styling of the Mustang that year, you would think that Ford had made the right move and was keeping up with the horsepower war that was taking place. But Bob Tasca, a Ford dealer who was involved with drag racing, didn't agree. He knew how strong the competition was becoming and didn't think the 390 was enough. So he took a '67 GT coupe that had a blown engine and replaced the 390 with a worked-over police interceptor 428 that had a set of 406 cylinder heads, the aluminum police interceptor intake manifold, a Holley four-barrel carburetor, and some other spicy bits from Ford's performance parts offerings. Backed up to a C-6 automatic, the prototype (known as KR-8) was stout enough to run 13 seconds in the quarter-mile at 105 miles per hour.

With the monster proven, Tasca showed Ford executives in Dearborn his creation, and in short notice Hot Rod magazine staffers started sniffing around after getting word about a hot big-block Mustang in Rhode Island that used factory parts. Once the article published, readers soon began sending in their letters to Ford, making their desires known: they wanted a copy of Tasca's Ford to put into their driveway. By April 1968, Ford had their answer ready: the 428 Cobra Jet.

For more insight about first-year Cobra Jet Mustangs, we spoke with journalist and photographer Eric English, a frequent Hemmings contributor. Eric has a unique perspective in that, he has not only written extensively about Cobra Jet-powered Fords of all stripes, he’s been the owner of a 1968 Mustang Cobra Jet hardtop since 1988 and has been a student of these cars ever since.

1968 Ford Mustang Cobra Jet - Body

The bodies of the ’68½ Cobra Jet-powered Mustangs were identical to their stablemates aside from the functional, bolt-on fiberglass hood scoops (of which there were different versions, due to running production changes) and hood stripes. The production cars were GTs, so they included the exterior trimmings that went with the package: C stripes on the sides, GT badges, quad exhaust tips, a flip-up GT gas tank filler, and fog lamps in the grille. Eric points out that since the production Cobra Jet Mustangs were all later-model-year cars, they had surface-mounted reflectors on the quarter panels that were used after February 1968, replacing the inset unit on earlier Mustangs.

“All production ’68½ Cobra Jets should have the later reflector on the rear. If it doesn’t, that’s a red flag: Is the car a fake or did it have incorrect replacement quarter panels put on it?”

Cobra Jet Mustangs have an R as the fifth digit of the VIN (Often they’re referred to as R-code Mustangs), so they are difficult to fake, and the Mustang 428 Cobra Jet Registry keeps tabs on these cars from 1968-’70.

Rust is every first-generation Mustang’s arch-enemy and these are no different. The floors and cowl are all susceptible to corrosion, as are the front torque boxes and the rockers—all of which can make the car unsound. Other areas of concern include the lower portions of the fenders, lower portions of the doors, rear wheel openings, and rear wheelhouses. Every panel needed to rebuild a Mustang body is reproduced—not just the exterior sheetmetal, but the skeletal bits as well. Complete reproduction bodies are available too. Obviously, owning a never-rusted Mustang is a good goal to have, but repair work that’s been performed to professional standards is nothing to shy away from these days. If the body has been reconstructed, ask to see in-progress photos of the work or to speak to the restorer.

1968 Ford Mustang Cobra Jet - Chassis

The Cobra Jet Mustangs shared their basic underpinnings with all first-generation Mustangs: independent front suspension with coil springs, upper and lower control arms, and an anti-roll bar. The front coil springs and hydraulic tubular shocks were mounted on top of the upper control arms, while strut rods helped locate the lower control arms. Towers flanking the engine bay served as mounting points for the upper arms and housed the coil springs. Variable-rate, semi-elliptic leaf springs soaked up the bumps in the rear, damped by hydraulic shock absorbers.

Staggered rear shocks also made their debut on the production Cobra Jets but only on cars equipped with four-speed manual transmissions. The Mustang’s Competition Handling Package was also part of the Cobra Jet’s repertoire, which added higher-rate springs, a 16:1 steering box, and a 15⁄16-inch sway bar. Power-assisted front disc and rear drum brakes were also mandatory on regular-production 1968 Cobra Jet Mustangs. Finding replacement parts needed to keep these cars rolling isn’t a major problem but, again, rust can be an issue. The shock towers can crack, and they also rust—as do the rear frame rails. All of the Mustang’s structural pieces can be replaced, but it’s not a simple or inexpensive task.

1968 Ford Mustang Cobra Jet - 428-cu.in. V-8 

Cobra Jet engine blocks were cast with additional reinforcement webbing to support the mains, an improvement made to all 428 blocks in early July, 1967. The Cobra Jet’s crankshaft was made of “nodular-controlled” cast iron and it swung forged steel rods with 13/32-24 x 2 5/32-inch bolts. Cast-aluminum pistons with dished tops and valve relief cutouts were attached to the rods with full-floating wrist pins. The camshaft in the production Cobra Jet was the same hydraulic cam used in the 390 GT/A. The Cobra Jet cylinder heads were unique but based around the design of the 1968 Cougar 427 heads. The Cobra Jet heads had rectangular intake ports measuring 2.34 inches by 1.34 inches (versus the 1.84-inch by 1.28-inch ports in the 390 heads) and were outfitted with 2.097-inch intake valves made of Silchrome alloy steel. The exhaust valves measured 1.66-inches and were made of forged steel. Cobra Jet heads also had threaded holes to accept Thermactor tubes as part of the smog/emission system necessary to meet the new federal emissions standards in 1968. A key to identifying Cobra Jet heads is by the C80E-N casting number located in the center of the heads between the spark plugs. Cobra Jet heads also had 16 threaded holes on the exhaust ports—four on each port—which differed from other FE heads with 14- or 8-bolt patterns.

The Cobra Jet’s intake manifold was made of cast iron and topped with a 735-cfm Holley carburetor. Spark came from a single-point, dual-advance distributor and low restriction cast-iron exhaust manifolds were used on Cobra Jet engines.

“Any of the early ’68-dated engine parts are a tough find compared to ’69 and ’70,” Eric says. “Blocks have gotten expensive and date-coded cylinder heads for a 68½ car would cost a lot more than ’69 or ’70 heads. Early intakes are super hard to find. Correct, early carburetors are hard to find and expensive—the air cleaner is tough to find too, and expensive, for ’68½ Cobra Jet Mustangs.”

A unique feature of 1968½ 428 Cobra Jet-equipped cars was a starter delay relay, which would interrupt power to the starter solenoid for four seconds if the engine was cranked but didn’t start—allowing the starter to cool off. Original units can be hard to find and costly; we spotted one for sale online priced at more than $2,000. Reproductions, priced between $1,500-$2,000, have been offered over the years, but availability can be spotty.

1968 Ford Mustang Cobra Jet - Transmission and Axle

The 428 Cobra Jet was paired with beefy drivetrain pieces designed to handle the rigors of drag racing. The four-speed was a heavy-duty close-ratio Toploader with a 1 3⁄8-inch, 10-spline input shaft and a 31-spline output shaft. An 11½-inch clutch provided positive engagement. The tags on the Toploader transmissions used in these cars were stamped “RUG-AE.”

The production C-6 automatic paired with Cobra Jets was tagged “PGB-AF,” and used a heavy-duty R-code intermediate servo (the letter R appears on the body of the servo). These C6s also had heavy-duty cast-iron tailshafts intended to prevent the torque of the engine from breaking the tailshaft mounts. The Cobra Jets used a 9-inch rear axle with a nodular third-member case and 31-spline axles. Gear ratios included: 3.50:1, 3.91:1 or 4.30:1. Traction-Lok was optional with the 3.50:1 ratio but mandatory with 3.91 or 4.30.

While replacement parts to rebuild or maintain a Cobra Jet’s drivetrain aren’t uncommon, correct transmission and rear-axle pieces for these cars can be difficult to come by and costly.

“If you’re getting down to date codes, earlier parts, like the nodular center section, are harder to find,” Eric says.

1968 Ford Mustang Cobra Jet - Interior

The Cobra Jet shared its cockpit with regular-production Mustangs. As such, it’s easy to restore one to like-new condition or to maintain a Cobra Jet’s interior with authentic parts. Bucket seats were standard issue, and a center console was optional in Mustangs. The Decor Group added niceties such as: a roof-mounted console with map lights (except convertibles); simulated woodgrain wheel; bright pedal trim; a vinyl grip insert on automatic shifters; wood grain instrument panel insert and more.

An 8,000-rpm tachometer was included on four-speed cars and optional with automatics. The oil pressure and amp gauges had to be deleted and replaced with warning lights on the dash to make way for the tach.

The original, production, Mustang Cobra Jet is a highly collectible car these days and iconic among the Blue Oval faithful. Finding one to purchase is a serious time and financial commitment but owners of these cars understand how significant the Cobra Jet is in the history of Mustang performance.

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