The Z28 is the most renowned Chevrolet RPO code. A high-performance option code has no equal. Known packages like Z22 and Z27 used other option codes, but the option names/descriptions became renowned, not the RPO number.
The Special Performance Package is not used. RPO Z28 ran from 1967 until 1974. 1975 and 1976 had no Z28s. The Z28 returned as a model in 1977, not an option package. The new model increased the Z28 name’s power.
History of Chevrolet’s Z28
Assisting the new 1967 Chevy Camaro in competing in the SCCA Trans-Am races, a road racing series gaining popularity among fans and manufacturers. The series’ V-8 engines couldn’t exceed 305 cubic inches. In 1966, the Shelby Mustang squad won the series with a 289-cid Ford Mustang.
The 327 was the smallest Camaro V-8. The 283 was the next available displacement, but not in Camaros. The two engines were easily combined. The 283’s 3-inch stroke crankshaft in the 4 inch bore 327 made a 302.4-inch hybrid engine. This was a road racing engine that could freely rev to 7,000 rpm. The 302 was rated at 290 hp, but it easily hit 350. The racing versions had 450 ponies.
There were 11:1 forged pistons, an aluminum high rise intake manifold, an 800-cfm Holley double-pump, and double-hump cylinder heads with 2.02-inch intake and 1.60-inch exhaust valves in the 302.
The Camaro had to be homologated to compete in the Trans-Am competition (offered as a regular consumer model). The SCCA required a minimum of 1,000 units, but only 602 Z28s were constructed in 1967. There was some sophisticated paperwork involving 350-cid Camaros as FIA Group I sedans and qualifying the same cars as Group II (Trans-Am cars) vehicles with the Z28 option.
Trans-Am champion Camaros won 10 of 13 races in 1968. Camaro won 8 of 12 races in 1969 to reclaim the title. GM, Ford, and Chrysler all competed fiercely in Trans-Am racing in 1969. It was gone by 1970.
The Z28’s name was as much a fluke as any meticulously designed focus group approach. The option was assigned RPO Z28, which stuck. The 1967 Z28 had no insignia. The wide racing stripes on the hood and trunk lid were the only exterior clues. A 302 or Z/28 symbol was on the fenders of 1968 cars. The slash between Z and 28 was used from 1967 to 1969, then omitted in 1970. The RPOs didn’t have slashes.
It was introduced on December 29, 1966. Cars started arriving in January and February. Three of the initial Z28s went to other GM divisions. The original purpose of 1967 Z28 production was to get them to favored dealers and racers. Chevrolet didn’t appear keen in publicizing the automobiles. Serious Z28 advertising began in 1968.
The car journals all lauded the Z28. It took a while to find a dealer who had the Z28 in stock. No air conditioning, and only coupes could be chosen with the Z28 option. J56 heavy-duty front disc brakes with metallic rear drum brakes with an M21 close-ratio four-speed manual. Positraction was advised.
15×6-inch rally wheels, 7.35×15-inch nylon tires, 3.73:1 rear axle ratio, and bonnet and trunk racing stripes were standard Z28 equipment.
Aside from the original 1967 Z28 equipment, a customer could choose two enhancements that were installed in the trunk. After Stage I, tubular exhaust headers were fitted. In the beginning, there was no specific hood. He extracted fresh air from the standard cowl vents via ductwork.
The new Z28 comes with the same warranty as other Camaros. Protection for the body was two years/24,000 miles, and the engine was five years/50,000.
Two-bolt main bearing caps for the 1967 302 and large-journal 2-bolt mains for the 1968 engines. 1967/1968 engine code is MO.
Flint, Michigan, constructed each engine. The Z28s were built at Norwood, Ohio, or Van Nuys, CA.
1968 Camaros were unchanged. The most visible changes were the insertion of side marker lamps and the removal of vent windows. The leading edge of the front fenders, right above the style crease, had “302” badges from September 1967 to early March 1968. The new Z/28 emblems came out in March.
Because Z28s were sold later in the model year, they are more common than 302s. Many 1967 and 1968 owners installed Z/28 badges.
The 1969 Camaro embodies the whole Z28 phenomena. Detroit and performance fans had a great year in 1969. Aside from the big-block muscle cars, there was plenty of activity with small-block cars. These cars competed on SCCA road courses and in showrooms. They stomped the Mustangs in both. The Z28 dominated Trans-Am racing and outsold the Boss 302 by 20,302 to 1,628.
Outwardly, all Camaros were altered, but mechanically, they were unchanged. The elevated hood scoop with rear entrance drew cold air into the engine area. The rally wheels were 15×7 and had Firestone E70-15 raised white letter tires. In place of the Z/28 stripes, emblems were added to the grille, taillight panel, and front fenders.
1969 engines had 4-bolt main bearing caps. The new suffix code was DZ. At $500, four-wheel power disc brakes were an option. The iconic dual-quad cross ram intake manifold. A cross ram arrangement in mint condition might cost as much as a vehicle.
The second-generation Camaros, introduced on February 26, 1970, were truly unique. The style was beautiful, especially on Rally Sport Appearance Package versions.
There were some notable variances under Z28 hoods. The new 350-cube engine was the most critical. Chevrolet’s Z28 was influenced by Trans-Am racing even though Chevrolet wasn’t directly involved. De-stroked engines are now legal in SCCA. In production automobiles, the 350 could be destroked to 305 cid to meet Trans-Am regulations. It was a win-win situation.
Other technical changes included automated transmissions in Z28s. No air conditioning yet.
The new Z28 engine was in the LT-1 Corvette. It had ten fewer horsepower (360 vs. 370), but the torque was the same. This resemblance indicates the engine’s real HP. The Corvette must rule Chevrolet. Extruded pistons, an aluminum intake manifold, and a Holley 780 cfm four-barrel carburetor were all part of the Z28 engine. The camshaft was milder than the 1969 302 cam.
Front discs remained standard, although JL8 four-wheel discs were no longer available. The F41 special suspension package was standard on other Camaros.
A low-profile rear deck spoiler was standard, but a three-piece higher spoiler was added a few months later. The Rally Sport option came with split bumpers and a body-colored Endura grille surround. In 1970, 8,733 Z28s were made.
However, a two-point compression drop left the 1971 Z28 with 30 horsepower (330 gross/275 net) and 20 pounds of torque less than the 1970 model. The solid-lifter cam remained. The steering ratios were tweaked. Z28 sales fell to 4,862.
In 1972, sales and horsepower fell. The Z28 now has 255 horsepower and 280 lb-ft of torque net. Sales fell nearly half from 1971 to 2,575 units.
1973 saw 280 lb-ft of torque but 245 hp net. A hydraulic camshaft replaced the Z28’s distinctive solid-lifter camshaft. The early Z28s had air conditioning, which was a little consolation.
However, the 1973 Z28 was still an outstanding performance car in a period of declining performance. That fact, along the Camaro’s still-stylish appearance, boosted sales to 11,574.
In 1974, performance remained unchanged, but look suffered due to new federal safety bumpers. The massive aluminum bumpers with black rub stripes transformed the car’s appearance. Large Z28 hood and trunk lid graphics detracted from the bumpers. The early Z28 insignia were gone. A 1974 Z28 could be seen from the air. Almost half of the 1974 Z28s have the huge decals. 1974 had no Rally Sport option.
RPO Z28 ended in 1974. Despite increasing sales, the Camaro Z28 was temporarily discontinued in 1974.
After two years without a Z28, the classic Camaro reappeared mid-year in 1977. The large bumpers were still there, but now they were body colored. On return, the Camaro got a bigger wraparound rear window. The Z28’s 350-cid V-8 produced 185 hp and 280 lb-ft of torque. The focus was on handling rather than pure acceleration. That meant firmer springs and thicker stabilizer bars on all Z28s. We used harder suspension bushings and shocks.
Even though the Z28 returned for only a few months, sales surpassed 1974 levels, with 14,349 vehicles built.
The 1978 Z28s got soft body-colored front and rear bumper coverings. It was a pleasant change from the bare aluminum bumpers. The 1978 Z28 has unique fender louvers and a customized hood. The public enjoyed the new look, and sales soared to a record 54,907 copies.
For 1979, styling improved. A new front spoiler with wheel holes. A redesigned hood scoop and a blacked-out grille complemented the body color. 84,877 units sold.
The Z28’s fender scoops and hood scoop were functional until 1980. There was no change in the base engine, which was a 190 hp 350 V-8 in California. 45,137 sold.
The second-generation Camaro ended in 1981. The 305 engine was the only way to have the four-speed manual transmission. The 175-hp 350 had the automatic. A single exhaust with two tailpipes summed up the Z28’s performance woes. Sales fell to 43,272 units.
Third-generation Camaros and Z28s began in 1982. The Camaro was brand new, yet it was still a Camaro. It was downsized yet didn’t appear smaller.
The Z28 emphasized handling. The 145-horsepower 305 engine couldn’t win many drag races. Only Z28s may get a 165-hp engine. Only the automated RPO LU5 engine was offered.
The 1982 Indy 500 Pace Car was a Camaro. Chevrolet produced 6,360 commemorative Z28s. A silver and blue automobile with Indy 500 graphics.
The new Z28 was positively regarded. Beyond the 6,360 pace cars, consumers ordered 64,882 standard Z28s for a total of 71,242.
In 1983, a five-speed manual transmission became standard on the Z28. The five-speed may be paired with a 190 hp L69 305 engine. The HO (High Output) (high output). The Z28 brought performance back.
In 1984, Z sales reached a milestone of 100,899 units. In 1985, the Z28 got more interesting with the new IROC-Z. Imported Camaros from the International Race of Champions were used to build the IROC-Z. RPO B4Z was the IROC Sport Equipment Package. It had 215 hp and was only available in Z28s.
The Z28 convertible debuted in 1987. In 1987, 744 Z28s were sold.
The big performance news was the return of the 350 V-8 in IROC guise. The 350 had 220 hp and was only offered in IROC-Z coupes.
In 1988, the Z28 emblem vanished, like in 1975 and 1976. It was the IROC-Z, not a simple Z28. In 1991, IROC-Z faded away and the Z28 resurfaced. Dodge took up the IROC event sponsorship.
1992 was the Camaro’s 25th birthday and the end of the third generation. To mark the occasion, a Heritage Appearance Package was created.
It had been 25 years for both the Camaro and Z28. As a fourth-generation Camaro, it would get even better over the next decade. Finally, the dormant Camaro made a comeback in 2009.