The Z/28 option code was introduced to the Camaro in December 1966 for the 1967 model year. It was the brainchild of Vince Piggins, who conceived offering "virtually race-ready" Camaros for sale from any Chevrolet dealer. This option package was not mentioned in any sales literature, so it was unknown to most buyers. The Z/28 option required power front disc brakes and a close-ratio Muncie 4-speed manual transmission (posi-traction was optional).
It featured a 302 cu in (4.9 L) small-block V-8 engine, 3" crankshaft with 4" bore, an aluminum intake manifold, and a 4-barrel vacuum secondary Holley carburetor of 780 cfm. The engine was designed specifically to race in the Trans Am series (which required engines smaller than 305 cu in (5.0 L) and public availability of the car. Advertised power of this engine was listed at 290 hp (216 kW). This is an under-rated figure. Chevrolet wanted to keep the horsepower rating at less than 1 hp per cubic inch, for various reasons (e.g. insurance and racing classes). The factory rating of 290 hp occurred at 5300 rpm, while actual peak for the high-revving 302 was closer to 360 hp (268 kW) (with the single four barrel carb) and 400 hp (298 kW) (with optional dual-four barrel carbs) at 6800-7000 rpm. The Z/28 also came with upgraded suspension, racing stripes on the hood and trunk lid, '302' front fender emblems on the 67 and early 68 cars, and 'Z/28' emblems in late 68 & 69. It was also possible to combine the Z/28 package with the RS package.
Source: Wikipedia (original)