The Super Cobra Jet 429 V-8 was the most powerful engine Mercury offered in the Cyclone for 1970. Its rating of 375 horsepower has long been accused of being too low, since this big-block’s performance was on par with big-inch specialty V-8s from GM and Chrysler. But what if that monstrously venomous V-8 was just the starting point for a potent street and strip machine that also managed to carry off that subtle elegance that always allowed Mercury to stand out from the crowd?
Before we answer that question, let’s look into Ford’s middle division muscle car for 1970 a bit more.
Positioned between the everyman’s Fords and luxury-liner Lincolns in the FoMoCo hierarchy, Mercurys were perpetually locked in a sales race with Buicks, Oldsmobiles, Pontiacs, and Dodges. Aiding in defining its upscale status within the muscle car market, the 1970 Cyclone GT included such amenities as concealed headlamps, additional body brightwork, and Comfortweave seating surfaces as standard equipment.
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The Cyclone’s redesign for the 1970 model year introduced the attention-getting “gunsight” grille center, a contemporary curvaceous body with a more subtle semi-fastback roofline than the previous years’ fastback, and three-pod taillights (two-pod on the base model).
Whereas the Cyclone Spoiler left little to the imagination regarding its muscle car intentions with its bold stripes, callouts, front spoiler, and rear deck airfoil, and the base Cyclone was a “sleeper” in appearance, the 1970 Cyclone GT took a different styling tack. It embodied what had become the signature elements of the performance car look at that time—a blacked-out grille, a hood scoop, dual racing mirrors, and well-placed yet understated GT badges and engine displacement emblems. The result provided more than enough clues for those in the know to realize what had just rumbled up next to them at the traffic light.
Typical of muscle cars of the day, the most powerful engines were reserved as extra-cost options, and the Cyclone GT did not disappoint in this area. At the top of the heap were a trio of big-block 429-cu.in. V-8 engines based on Ford’s 385 engine family.
The ”base” 429 was a smooth-running 360hp version that featured a two-bolt main, thin-wall skirtless engine block with 4.36-inch bores; a nodular-iron crankshaft with a 3.59-inch stroke; forged-steel connecting rods; cast-aluminum pistons; a hydraulic camshaft; canted-valve cylinder heads; a cast-iron intake manifold; Autolite four-barrel carburetor; and a 10.5:1 compression ratio.
Next up the ladder was the high-performance 370hp Cobra Jet 429, which featured thicker main webs in its block, higher nodularity content in its crankshaft, a slight modification to the forged-steel rods to increase durability; a hotter hydraulic camshaft; freer-flowing heads (larger ports and valves) and intake and exhaust manifolds; a Rochester Quadrajet four-barrel; and an 11.3:1 compression ratio.
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At the top of the engine heap sat the 375hp 429 Super Cobra Jet, but there was no option box to check to get this special engine. Instead, a buyer had to choose either the Drag Pak, which consisted of a 3.90:1 gearset in a Traction-Lok rear axle or the Super Drag Pak, which included a 4.30:1 gearset in a Detroit Locker rear axle. Though the engine code in the VIN remained the same as the CJ 429’s, the Super Cobra Jet’s upgrades included a four-bolt main block, forged pistons, and a higher-performance solid-lifter camshaft, as well as screw-in studs for the CJ heads, adjustable rocker arms, and pushrod guide-plates. A specific intake manifold accommodated a larger capacity Holley carburetor instead of the CJ’s spread-bore Quadrajet, and an oil cooler was added. Functional Ram Air was available for the CJ and Super CJ, as well.
Now, back to the build at hand. Currently offered on Hemmings Auctions is this restored, low-mileage 1970 Mercury Cyclone GT, factory fitted with the 429 SCJ and the requisite Drag Pak along with a close-ratio four-speed manual transmission. According to its Deluxe Marti Report, this rare Cyclone is one of just 73 produced for 1970 with the 429 Super Cobra Jet and the Drag Pak.
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Beyond the engine and Drag Pack options, the original buyer of this vehicle chose the extra-cost instrumentation group, which included a 140-mph speedometer, as well as an 8,000-rpm tachometer, gauges for oil pressure and temperature, and an ammeter, all of which are set right into the dash pad and angled toward the driver for easy viewing. Power front disc brakes were also chosen, among other options. The Competition Handling Package was included with the GT, and due to its chosen powertrain, as intended by Mercury and the original buyer. This example was a potent package for the street or strip.
Making it even more so now is the fact that the selling dealer, MS Classic Cars of Seekonk, Massachusetts, had the numbers-matching engine bored-and-stroked to a colossal 533 cubic inches. Heavier-duty bottom-end components and a solid-roller camshaft were added to complement the CJ heads and Super CJ intake and carburetor, and the result was a tire-shredding 527 horsepower and 599 pound-feet of torque on the dyno.
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This car’s restoration is recent and thorough, resulting in a highly detailed undercarriage that shows every bit as well as its topside. With so few 1970 Mercury Cyclone GTs built with the Drag Pak/Super CJ 429, surely not many under-16,000-mile examples that are restored to this level and produce more than 500 dyno-proven horsepower will be offered for sale anytime soon.
Learn more about this 1970 Mercury Cyclone GT on Hemmings Auctions, and let us know what you think of it.
![1970 Mercury Cyclone GT on Hemmings Auctions]()
