Before the Shelbys and Bosses arrived, the Ford Mustang K-Code was the peak of pony car performance. On a newly released episode of Jay Leno's Garage, Mustang enthusiast Scott McMullen explains the significance of the K-Code, and shows off this restored first-year example.
The K-Code went on sale along with the Mustang itself in the 1964 calendar year, but later enough that the first cars were registered as 1965 models, which is why you'll hear the convertible shown in this video and other first-year Mustangs referred to as "1964 1/2" models. Ford offered the K-Code option for both the coupe and convertible body styles, as well as the fastback when that body style arrived later in 1964.
1964 1/2 Ford Mustang K-Code convertible on Jay Leno's Garage
Selecting the K-Code option netted a sportier version of the Mustang's optional 289-cubic-inch V-8, boasting a 10.5:1 compression ratio, a solid-lifter camshaft, four-barrel carburetor, heavy-duty valve springs, and a high-flow exhaust manifold. These parts upped output to 271 hp, which is sent to the rear-wheels through a 4-speed manual transmission with the same ratios used in the later Mustang Shelby GT350.
Ford made some suspension changes as well, with input from racing legend Dan Gurney. Interestingly, after driving prototypes, Gurney preferred the heavier, less-rigid Mustang convertible to the coupe, according to McMullen. That's because added bracing (sourced from the Thunderbird) gave the convertible a lower center of gravity.
The K-Code was a true sleeper, with the main giveaway being "High Performance 289" badges on the front fenders. Ford hadn't fully committed to marketing the Mustang as a performance car when it was launched. That would come later when executive Lee Iacocca brought in Carroll Shelby to create the GT350, which would be followed by a serious of ever more muscular Mustangs, such as the Shelby GT500 and Boss 429, through the end of the 1960s.
The car shown here is among the first production K-Code Mustangs. It was built in June 1964 following several delays related to parts issues and other factors, McMullen says in the video. It's been restored as close to original condition as possible. Some body panels needed to be replaced, but McMullen consulted with the original owner on all of the details, and even tried not to overdo the paint finish beyond factory quality, so it's the perfect teaching tool for an important part of Mustang history.