1968 Chevy Impala SS 427
When it returned in 1968, the Impala Super Sport 427 reflected both styling and marketing changes from the previous season. Chevrolet Motor Division adopted a new technique of sculpting bodies by stretching cloth over a wire frame and blowing it out to create "fluid" shapes. The result was a smoother, softer appearance. Chevy also dropped the separate Impala SS series, replacing it with a new Z03 Super Sport option package. Priced at $179.05, it included essentially the same extras taht cars in the 1967 Impala SS series had.
Another of Chevrolet's marketing changes involved makin the performance option available for three Impala models, instead of just two. You could order it for the $2,968 sport coupe, the $3,021 custom coupe or the $3,197 convertible. The custom coupe had a more formal roofline and lower production total.
Making the SS an option made the SS 427 package an "option for an option." Coded RPO Z24, it had all of the basic SS features, plus a special performance hood, red-stripe tires, 15-inch wheel rims and the RPO L36 427-cid Turbo-Jet engine for $358.10. This "standard" version of the 427 had a 10.25:1 compression ratio. It developed 385 hp at 5200 rpm and 460 lbs.-ft. of torque at 3400 rpm.
Chevrolet buyers could also spend $542.45 to get a second SS 427 package featuring the L72 version of the engine with 11.0:1 compression. It was good for 425 hp at 5600 rpm and the same 460 lbs.-ft. of torque at a higher 4000 rpm.
Unfortunately, the 1968 Impala SS 427 proved ineffective in boosting big-car sales to enthusiasts. Total production of Impalas with Super Sport equipment took a big drop to 38,210 units. A mere 1,778 had the SS 427 option. Experts say the 1968s are teh more desirable to collectors, but they also represent the easiest SS 427 model to fake. This is because they were not coded as an individual series model.
In September 1968, Hot Rod magazine published an article entitled "600-Plus Horsepower from Chevy's 427" that covered some 427-cid racing modifications that could produce 600 hp. It also talked about the availability of a "triple two-barrel" carburetor system option. According to editor Eric Rickman, this setup used primary No. 3925517 and secondary No. 3902353 in conjunction with the 1967 manifold No. 3904574. While perhaps not strictly stock, a 600-hp SS 427 would be a helluva muscle car.