The Z/28 option code was introduced in December 1966 for the 1967 model year. This option package wasn't mentioned in any sales literature, so it was unknown to most buyers. The Z/28 option required power front disc brakes and a Muncie 4-speed manual transmission. The Z/28 featured a 302(5.0L) small-block V-8 engine, 3" crankshaft with 4" bore, an aluminum intake manifold, and a 4-barrel vacuum secondary Holly carburetor of 780CFM. The engine was designed specifically to race in the Trans Am series (which required engines smaller than 305(5.0L) and public availability of the car. Advertised power of this engine was listed at 290hp (216kW). This is an under-rated figure. Chevrolet wanted to keep the horsepower rating at less than 1hp per cubic inch, for various reasons (e.g. insurance and racing classes). The factory rating of 290hp occurred at 5300 rpm, while actual peak for the high-revving 302 was closer to 360hp (with the single four barrel carb) to 400hp (with optional dual-four barrel carbs) (269 to 298kW) at 6800-7000 rpm. The Z/28 also came with upgraded suspension, racing stripes on the hood, and 'Z/28' emblems for the fenders (in 68 & 69). It was also possible to combine the Z/28 package with the RS package. Only 602 Z/28s were sold in 1967. The 1967 and 1968 Z/28s did not have raised cowl induction hoods as was optional on the 1969 Z/28s. The 1967 Z28 received air from an open element air cleaner or from an optional cowl plenum duct attached to the side of the air cleaner that ran to the firewall and got air from the cowl vents. 15-inch rally wheels, were included with Z/28s had while all other 1967-9 Camaros had 14-inch wheels. In '68 the Z28 appeared in Camaro brochures. 7,199 Z28s were sold in 1968.