The small block Shelby Cobra Mustangs.
The 1968 Shelby Mustangs came in two flavors, a small block and a big block. The small block cars were called GT 350. The 1967 GT 350 had the HiPo 289 solid lifter engine. Ford bumped up the displacement in 1968 to 302 engine. Using the same basic block as the earlier 289, the Ford 302 was the next step in the evolution of the Ford small block engine.
First year for the convertible Shelby Mustangs
For the first time, buyers could order a convertible version of a Shelby Mustang. Convertible Mustangs were offered from the beginning in 1964 1/2 but it wasn’t until 1968 that a Shelby convertible was available. Like the fastbacks, the Shelby convertibles had a roll bar installed. There were special clips on the top said to be there to help secure a surf board.
The 68 Shelby Mustangs were modified in Michigan
The 1968 Shelby GT 350 was a continuation of the ’67 Shelby model. The cars were shipped to AO Smith in Ionia, Michigan from Ford’s assembly plant in Metuchen, New Jersey. Read more about how the Shelby Mustangs ended up being in Michigan instead of California.. click here 1968 Shelby Cobra Story.
The 1967 cars were shipped to Shelby American at the Los Angeles airport for modifications. The cars were built as Mustang GT’s with heavy duty suspensions, only slight suspension changes were made. The buyers in ’67 demonstrated with their pocketbooks they wanted fewer all out performance options and more luxury features. The suspension changes were special Shelby only coil and leaf springs that became more stiff under stress, yet under normal driving yielded a better ride. The front sway (stabilizer) bar was thicker (.94″) than the GT Mustang and adjustable, Gabriel shock absorbers replaced the GT shocks.
Gone was the hipo 289 engine
The primary difference, other than the cosmetics, between the ’67 GT 350’s and the ’68 GT 350’s was the engine. Ford discontinued the hi-po 289 after ’67 and introduced the 302. Gone was the mechanical lifter, Shelby 306 HP version of Hi Po 289. The Shelby version of the new 302 engine was rated at 250 HP. Stock rating for the hydraulic lifter, Ford 302 was 230 HP.
Shelby replaced the stock cast iron intake manifold with an aluminum, Cobra hi-rise, dual plane with a Holley 4 barrel carb setting on top. Shelby had Offenhauser make the aluminum intake to Shelby specs. This intake was designed to increase torque at lower RPMs. The very early cars carried the stock cast iron intakes because the factory couldn’t get an ok on the emission tests using the aluminum hi-rise and Holley carb. A unique option offered for the small block version was a Paxton supercharger which increased the horsepower by 40% to about 335 horse. Big block horsepower from a small block Ford. For a few dollars more though, the buyer could get a GT 500, so very few superchargers were actually installed.
John Chun designs the ’68 Shelby Mustangs
Some years ago, i ran into John Chun at a local car show. He walked up to me next to my Shelby. The first thing he said to me was “I designed that car.” I met with John a number of times. He had some great stories. He told me his assignment was to come up with a design for the ’68 cars. And he had to do right economically. One way to save production costs was to use off the shelf Ford parts. Thus John proposed using 1965 Thunderbird sequential tail lights mounted in a special fiberglass panel across rear of the Mustang body, John gave me copies of his original sketches which are on his pages on this site. Click here to read about Johp, John Chun – Designer of the 1968 Shelby Cobras.
The factory offered performance and dress up parts like headers, Koni shocks and a unique shift knob. Ram air was standard on the GT 500KR, an option on the GT 350. The ram air option was a bonnet that ducted air through the front hood air scoops directly to the air cleaner and carb. It fit under the hood with a cut out for the air cleaner.
Above is a picture of the engine compartment in my ’68 GT 350. Note the low restriction oval Cobra air cleaner and the Cobra valve covers. Both were painted black with the silver letters with no paint. The oval air cleaner is the same size as the one used for the dual 4 barrels, although the GT 350 came with a single 4 barrel. The ’68 Shelby Mustangs had mandatory power steering and power brakes with discs in the front and drums in the rear. My car has an upgraded three core, big block radiator. Read about the mods I’ve done to the 302 engine, brakes and suspension on my car by clicking here My 1968 Shelby Cobra GT 350.
Strengthened the front end
The Shelby Mustangs came with a one piece export brace. The stock Mustang had a two piece. My car has a after market, curved Monte Carlo bar brace across the front of the engine compartment. This bar is curved to accomodate the oval Cobra air cleaner. The Monte Carlo bar comes from the brace used on the Falcons raced in Monte Carlo. The unibody Mustang and Falcons tended to flex, especially if driven aggressively. These two braces tighten up and strengthen the body. Carroll Shelby recommended the Monte Carlo bar for the Falcons.
The GT 500 Shelby Mustangs
Specs for the 1968 Shelby Cobra Mustangs
I put together a page with the specifications, measurements and details on the ’68 Shelby Mustangs. I included a column for the current specs on my GT350. Click here to go to that spec page, 1968 Shelby Cobra Specifications
I collected many of the magazine ads for the 1968 Shelby Mustangs, click here, 1968 Shelby Mustang Ads & Brochures.
|Production Figures for 1968 Shelby Cobra (Mustangs)|
|GT 350 Convertible||404|
|GT 500 Convertible||402|
|GT 500 KR||933|
|GT 500 KR Convertible||318|
|GT 500 Notchback Prototype||1|
|Total Production of 1968 Shelby Mustangs||4,451|