Text by Bruce Caldwell, photos by Bruce Caldwell and Jerry Heasley.
Z28 is the most famous Chevrolet RPO (regular production option) code ever. No other option code has become so synonymous with high performance. Other option codes have been used for well-known packages such as Z22 (Rally Sport) and Z27 (Super Sport), but the option names/descriptions became famous, not the RPO number.
RPO Z28 is known as the Special Performance Package, but no one uses that name. RPO Z28 was in effect from 1967 through 1974. There were no Z28s in 1975 and 1976. When the Z28 returned in 1977 it was as its own model, not an option package. The change to a separate model reinforced the power of the Z28 name.
The Z28 came about as a means of making the new 1967 Chevy Camaro competitive in the SCCA Trans-Am races, a road racing series that was rapidly gaining popularity among spectators and auto manufacturers.
The series had a 305 cubic-inch displacement limit for V-8 engines. Ford Mustangs (289-cid) and Dodge Darts/Plymouth Barracudas (273-cid) were dominating the series in 1966, with the Shelby Mustang team winning the championship.
The smallest displacement Camaro V-8 was the 327. The next available displacement was the 283, although it wasn't offered in Camaros. A slick solution was to marry the two engines. By putting the 283's 3-inch-stroke crankshaft in the 4-inch-bore 327, a hybrid 302.4-inch engine emerged. This was an engine ideally suited to road racing that freely revved to 7,000 rpm. The 302 was rated at 290 horsepower, but it easily hit 350 on a dynamometer. Racing (blueprinted) versions were reportedly closer to 450 ponies.
Key 302 components included 11.0:1 forged pistons, a high-lift, solid-lifter camshaft (as used in 1964-65 Corvettes), an aluminum high-rise intake manifold, an 800-cfm Holley double-pumper, and double-hump cylinder heads with 2.02-inch intake and 1.60-inch exhaust valves.
In order to compete in the Trans-Am series, the Camaro needed to be homologated (offered as a regular consumer model). The SCCA production minimum was 1,000 units, but the Z28 managed to go racing even though only 602 cars were built in 1967. There was some fancy paperwork involving 350-cid Camaros as FIA (the international racing sanctioning body Federation Internationale de l'Automobile) Group I sedans, and qualifying the same cars as Group II (the Trans-Am cars) vehicles with the Z28 option.
Legendary Corvette racer/tuner Dick Guldstrand drove a Z28 to its first victory at the 1967 St. Jovite race in Quebec, Canada. There was a steep learning curve that first year, but by the end of the season the Z28s were gaining steadily. Mark Donohue won the last two races, which put the Camaro third behind Mustang (first) and Cougar (second). Camaros dominated the 1968 Trans-Am, winning 10 out of 13 races and the championship. Camaro claimed the championship again in 1969, winning 8 out of 12 races.
1969 was the zenith of Trans-Am racing, with intense competition from General Motors, Ford, and Chrysler. By 1970, factory support was dwindling (except for American Motors, who lured the nearly unbeatable Roger Penske team away from Chevrolet). To no one's surprise, the Penske juggernaut with its star driver, Mark Donohue, won the 1970 Trans-Am championship.
NAMING THE Z28
The man most responsible for the Z28 was Chevrolet's Vince W. Piggins. His concept, with strong backing from Chevrolet General Manager Pete Estes, got the Z28 produced. Vince wanted the new Camaro to beat its rival Mustang at every possible venue.
Naming the Z28 was as much happenstance as any carefully researched, focus group-influenced process. Vince Piggins liked the name Cheetah (a Chevy performance footnote–Cheetah was the name of the awesome-but-short-lived Bill Thomas sports car), but just before an early demonstration session, he removed the Cheetah decals.
RPO Z28 was assigned to the option, and it ended up sticking. The original 1967 Z28 didn't carry any emblems. The only exterior clue to the car's performance was the wide racing stripes on the hood and trunk lid. The 1968 models had either a 302 or a Z/28 emblem on their front fenders.
The slash between Z and 28 was used on the first-generation 1967-69 cars, and then were dropped in 1970. Slashes weren't part of the RPO designations.
Camaro Z28 production began on December 29, 1966. Cars started trickling into dealerships in January and February. Three of the first twenty-five Z28s actually went to other GM divisions.
The initial goal of 1967 Z28 production was to get the cars into the hands of favored dealers and qualified racers (often one and the same). Chevrolet didn't seem particularly interested in marketing the cars to the general public. Serious Z28 advertising didn't start until 1968.
All the car buff magazines loved the new Z28. Not all dealerships were in tune with the Z28, so it took some persistence to order one. Air conditioning was not available, and the Z28 option could only be ordered on coupes. Ordering an M21 close-ratio four-speed manual was mandatory, as were J56 heavy-duty front disc brakes with metallic rear drum brakes. Positraction was highly recommended.
Standard Z28 features included the 302-cube engine, dual exhaust, heavy-duty radiator, temperature-controlled fan, heavy-duty front and rear suspension, quick ratio steering, 15x6-inch rally wheels, 7.35x15-inch nylon tires, 3.73:1 rear axle ratio, and hood and trunk racing stripes (black or white, depending on paint color).
In addition to the standard 1967 Z28 equipment, a buyer could opt for two upgrades that were placed in the trunk for the new owner. Stage I was a cowl induction air cleaner, and Stage II added tubular exhaust headers. This initial cowl induction system didn't use a special hood. Rather, it had ductwork that drew fresh air from the regular cowl vents.
A neat fact about the new Z28 is that it came with the same warranty as other Camaros. Coverage was for two years/24,000 miles bumper-to-bumper, and five years/50,000 miles on the powertrain. That's a lot of revs on a 302!
The 1967 302 had small-journal, 2-bolt main bearing caps, and the 1968 engines had large-journal, 2-bolt mains. The engine code for 1967/1968 is MO. All the engines were built in Flint, Michigan. Z28s were assembled in Norwood, Ohio, or Van Nuys, California.
Camaros were little changed for 1968. Outwardly, the two most noticeable differences were the addition of side marker lamps, and the elimination of vent windows. 1968 Z28s manufactured from the start of the model run in September 1967 through early March 1968 had "302" emblems at the leading edge of the front fenders, just above the styling crease. In March, the new Z/28 emblems were instituted.
1968 Z/28 emblem cars are more prevalent than the 302 cars, because a greater percentage of Z28s were sold later in the model year (total 1968 sales: 7,199 units). Also, many 1967 and early 1968 owners added the Z/28 emblems.
If there is one Camaro that exemplifies the whole Z28 phenomenon, it's the 1969 model. 1969 was a banner year for Detroit and high-performance enthusiasts. Much of the media attention focused on the big-block muscle cars, but there was also lots of action with small-block-powered cars. The Z28 and its rival, the Mustang Boss 302, competed on SCCA road courses and in showrooms. The Camaros stomped the Mustangs in both venues. The Z28 won the Trans-Am championship, and outsold the Boss 302 by a landslide 20,302 units to 1,628.
All Camaros were noticeably changed outwardly, but mechanically, things remained similar to 1968. A popular styling/functional change was the raised hood scoop with the rear opening that helped draw cold air into the engine compartment. The rally wheels gained an inch of width to 15x7, and came with Firestone E70-15 raised white letter tires. The Z/28 stripes were no longer unique to Z28s, so badges were added to the grille and taillight panel as well as the front fenders.
The 1969 engines were upgraded to 4-bolt main bearing caps. The new engine suffix code became DZ. Four-wheel power disc brakes were an available option (RPO JL8), but at $500 very few Z28s received them. Another legendary service option (not an RPO, but available through Chevrolet parts departments) was the dual-quad cross ram intake manifold. The cross ram setup is so rare and desirable that a complete, mint condition one can cost as much as a whole car.
Radically different is an accurate way to describe the second-generation Camaros, which debuted on February 26, 1970. The styling was very handsome, especially on models outfitted with the Rally Sport Appearance Package (Z22).
Under Z28 hoods there were a couple significant differences. The most important one was the new, larger displacement, 350-cube engine. Even though Chevrolet wasn't as actively involved in Trans-Am racing, the Z28 (the emblem slash was gone for good in 1970) was still influenced by the series. A major SCCA rule change allowed engines to be de-stroked. The 350 could be de-stroked to meet the Trans-Am 305-cid limit, and the larger, more tractable engine could be sold in production cars. It was an everybody-wins situation.
The other big mechanical change was the availability of automatic transmissions in Z28s. Air conditioning was still not available.
The new Z28 engine was essentially the Corvette LT-1. It was rated at ten less horsepower (360 vs. 370), but torque ratings were the same (380 lb-ft). That similarity is a clue to the engine's true horsepower. In the Chevrolet hierarchy, the Corvette has to dominate. The Z28 engine had 4-bolt mains, a forged steel crankshaft, 11.0:1 extruded pistons, an aluminum intake manifold, and a Holley 780-cfm, four-barrel carburetor. The camshaft was slightly less aggressive than the 1969 302 cam.
Front disc brakes were still standard, but the one-year optional JL8 four-wheel discs were gone. The standard suspension was the F41 special suspension package that was optional on other Camaros.
A low-profile rear deck spoiler was standard, but a new three-piece taller spoiler became available a couple months after production started. A traditional one-piece bumper was standard, but when the Rally Sport option was ordered it came with split bumpers and a body-colored Endura grille surround. The shorter 1970 sales year resulted in 8,733 Z28s being produced.
The 1971 Z28 was very similar to the 1970 model, except that a two-point compression drop left behind 30 horsepower (330 gross hp/275 net hp) and 20 fewer pounds of torque. The solid-lifter cam was still the same. Steering ratios were slightly changed. Z28 sales dropped to 4,862 units.
Sales and horsepower continued to drop in 1972. Horsepower figures were now net, leaving the Z28 with 255 hp and 280 lb-ft of torque. Sales dropped by almost 50 percent from 1971, to 2,575 units.
Torque stayed the same for 1973 at 280 lb-ft, but net horsepower dropped another 10 to 245 hp. The Z28's signature solid-lifter camshaft was replaced by a milder hydraulic setup. A small consolation was the first-time availability of air conditioning in Z28s.
Even though overall performance was down, the 1973 Z28 was still a standout performance car in an era of ever-decreasing performance. That fact–and the Camaro's still-handsome styling–helped sales take a huge upsurge to 11,574.
Performance remained the same for 1974, but appearance took a nosedive due to the newly mandated federal safety bumpers. The big aluminum bumpers with black rub strips made a huge difference in how the car looked. Optional, oversized Z28 hood and trunk lid graphics (RPO D88) drew attention away from the bumpers. The early days of extremely subtle Z28 emblems were long gone. Airplane passengers could spot a 1974 Z28 from the sky. Approximately half of the 1974 Z28s (6,978 of 13,802) were ordered with the big decals. There was no Rally Sport option for 1974.
1974 was the end of the line for RPO Z28. Even though sales were on an upswing, the Camaro Z28 was temporarily discontinued after 1974.
After two years of no Z28s, the iconic Camaro returned as a separate model mid-year in 1977. The big bumpers were still around, but at least they were body colored on the revived Z28. During its hiatus, the Camaro gained a larger, wraparound rear window. The 1977 Z28 was powered by a 350-cid V-8 that was rated at 185 horsepower and 280 lb-ft of torque. The performance emphasis was more on handling than all-out acceleration. Toward that goal, all Z28s had stiffer spring rates and thicker stabilizer bars. Harder suspension bushings and firmer shocks were used.
Even though the returning Z28 didn't enjoy a full model year, sales picked up at 1974 levels and actually ended slightly higher, with 14,349 units produced.
The 1978 Z28s were moderately restyled with soft, body-colored front and rear bumper covers. That was a welcome improvement over the previously exposed aluminum bumpers. The 1978 Z28 had some specific trim items such as unique fender louvers and a special hood. The public liked the revised styling, as sales skyrocketed to 54,907 units–an all-time record.
Styling improved again for 1979. A new front spoiler wrapped around to the wheel openings. A bolt-on hood scoop was new, and a blacked-out grille contrasted with the main body color. Sales jumped to 84,877.
For 1980, the Z28's fender scoops became functional, as did a new cold air hood scoop. The 190-hp 350 V-8 was still the standard engine, except in California where a 165 hp 305 was used. Sales dropped to 45,137.
1981 was the final year of the second-generation Camaro. It was still a handsome car, but performance suffered as the four-speed manual trans could only be had with the 305 engine. The 175-hp 350 could still be had with the automatic. A single exhaust, but with two tailpipes pretty well summed up the sorry state of Z28 performance. Sales declined slightly to 43,272 units.
1982 was the start of third-generation Camaros and Z28s. The Camaro was all new, but it still was readily identifiable as a Camaro. It was downsized, but didn't really look much smaller.
Handling was the key Z28 emphasis. That was good, since the 145-horse 305 engine couldn't win many drag races. There was a 165-hp engine option that was limited to Z28s. The RPO LU5 engine was only available with the automatic.
Camaro was again chosen as the Indy 500 Pace Car for the 1982 race. To mark the occasion, Chevrolet produced 6,360 Z28 Commemorative Editions. All the cars were silver and blue with Indy 500 graphics.
The new third-generation Z28 was very well received. In addition to the 6,360 pace cars, customers bought 64,882 regular Z28s for a total Z28 production of 71,242.
Things were visually similar for 1983, but a five-speed manual transmission became standard Z28 equipment for the first time. The five-speed could be mated to the optional L69 305 engine that produced 190 horsepower. This engine was known as the HO (high output). Performance was on its way back via the Z28.
Z sales continued to climb, hitting a benchmark 100,899 units in 1984. The numbers dropped in 1985, but the Z28 got more exciting with the addition of the new IROC-Z. The IROC-Z (named after the International Race Of Champions, where champion drivers competed in identical Camaros) became the top Z28. RPO B4Z was the IROC Sport Equipment Package–an impressive handling package. A new TPI (tuned port injection) engine produced 215 horses, and was only available in Z28s.
In 1987, the Z28 convertible was introduced. An outside firm, ASC (Automotive Specialty Company), did the conversions. Only 744 Z28 convertibles were sold in 1987.
The big performance news was the return of the 350 V-8 in the form of an optional IROC engine. The 350 was rated at 220 horses, and was only available in IROC-Z coupes.
Like in 1975 and 1976, the Z28 badge disappeared again in 1988. It was essentially there as the IROC-Z, but not a plain Z28. There was another switch in 1991 when IROC-Z disappeared for good and the Z28 returned. The IROC event sponsorship was taken over by Dodge.
1992 marked the 25th anniversary of the Camaro, and the end of the third generation. There was a special Heritage Appearance Package to commemorate the occasion.
Both the Camaro and the Z28 were strong and healthy after 25 years. The iconic model would get even better during its last 10 years as a fourth-generation Camaro. And finally, the dormant Camaro returned as a 2010 model in 2009. There is a Super Sport model, but so far, no new Z28. We doubt that will be the case for long. The Camaro Z28 is such a revered model that it will surely rise again–possibly in a 500-plus-horsepower supercharged street brawler. Long live the Z28.
This is the engine that formed the foundation around which the 1967 Z28 was built. A 283 crankshaft was installed in a 327 block to create a 302-cid screamer that fit within the SCCA Trans-Am 305-cube limit.
The unique Z28 stripes and 15x6-inch rally wheels with disc brake center caps are the only external clues that this is a 1967 Z28.
Many first-generation Z28s went straight from the showroom to the racetrack. Many others were soon converted and many, like this 1968, still compete in vintage races.
By 1968, Z28s were easier to identify, because they either had a Z/28 emblem or a 302 emblem on their front fenders. This 1968 Z also has the desirable Rally Sport package (RPO Z22). The Z28 emblem suggests it was built later in the model year.
This 1968 Z28 (also British Green with white stripes) was built earlier in the model year as evidenced by its 302 front fender emblems. It has the standard exposed headlights.
This 1968 MO-code 302 engine has the correct 1968 AIR (air injector reactor) smog pump with its deep groove pulley.
This beautifully restored Hugger Orange 1969 Z28 has the relatively rare RPO VE3 body colored front bumper. The car also has the white vinyl roof, white interior, and white stripes.
Here is another Hugger Orange 1969 Z28, but it's equipped with the more common chrome front bumper. It has a black interior and no vinyl top.
This is the most well-known Z28 engine, the legendary DZ-code 1969 302 equipped with the cowl-induction hood package RPO ZL2.
Not all Z28s have retained their original running gear. 1969 Z28s in particular are very popular as modified Camaros. Without their original engines, such cars are more modified Camaros than Z28s.
The second-generation 1970 Z28 is considered by many experts to be the ultimate early Camaro. It was a very well balanced, do-everything car with incredibly handsome styling.
The 1970 Z28 engine's displacement increased to 350. Horsepower was a stout 360, with 380 lb-ft of torque. When mated to a four-speed manual it made for an awesome performer.
By 1974, the Rally Sport option was gone. All Z28s received massive aluminum safety bumpers.
The new second-generation Z28 wheels were quite handsome, and could be painted body color. They came with bright trim rings and chrome lug nuts.
The late 1970s and early 1980s Z28s (this is a 1978) were attractive cars now that their bumpers were covered.
The totally redesigned and slightly smaller 1982 (third-gen) Camaro Z28 was chosen to pace the Indy 500. A limited number of replicas (6,360) were built for the public.
This is the optional 1982 Z28 engine (RPO LU5) that produced 165 hp. It featured the unique Cross-Fire throttle body injection system.
The IROC-Z started in 1985 as the deluxe edition of the Z28, and stayed that way until 1988 when it became the sole Camaro Z-car. The last IROC-Z editions were 1990 models.
The Camaro convertible returned in 1987, and could be had in all trim levels including the very popular IROC-Z.
By 1991, the Z28 rear spoiler had grown substantially. The big spoiler was also used in 1992.
The end of the third-generation Camaro run was commemorated with a 25th Anniversary Heritage Edition. Part of the package was this headrest logo.
Published Dec 7th, 2015