It won’t be long before the fifth-generation Camaro will be introduced with the 422hp LS3 engine. It’s been forty years since Chevrolet built a Camaro with that kind of power. Back in 1969, a small number of racers and street freaks got their mitts on what were dubbed COPO Camaros, and these 427ci-powered Bow Tie bruisers sucked the headlamps off anything that challenged them on the strip or the street.
The COPO series of special-order Camaros were born in the go-go era of the late ‘60s before the Federal Government came crashing down on Detroit’s freedom to build ragged-edge, extremely powerful muscle cars with little regard to sanity (or GM policy). Since Central Office Production Orders were not production cars in the literal sense of the word, they weren’t subject to corporate restrictions for displacement, power to weight ratios, or other boundaries. COPO allowed production options to be combined into packages that weren’t offered together on the factory order forms and usually applied to fleet orders for taxis or school buses, however, in this case it was for a series of pavement-shredding Camaro supercars.
The idea of building COPO muscle cars started with Fred Gibb, who ordered fifty 1968 L78 Novas fitted with M40 Turbo Hydra-Matics—the minimum number to qualify for NHRA drag racing. Only manual transmissions were offered with solid lifter L78s in Novas, so the COPO order was issued to mate the 375hp big-block to the automatic. This order opened the floodgates for a series of COPO orders in 1969 for Camaros and Chevelles to be fitted with either the L72 iron Mark IV engine, or the all-aluminum ZL1 in Camaros and Corvettes.
Only 69 of the exotic (and prohibitively expensive) ZL1s were built, however production of the L72 Camaros (designated COPO 9561 AA for four-speed cars and BA for M40s) was far higher since it cost only $489.75. Exactly 822 9561 AA and 193 BA COPOs were built. Of this 1,015 total, orders for 201 were made by Yenko Chevrolet (who initiated the package with Chevrolet), 50 by Berger Chevrolet, and smaller amounts dispersed to other Chevrolet performance dealers.
COPO 9561 started with RPO L72, a 427ci four-bolt main iron block with 11.0:1 squish, forged aluminum pistons pinned to forged steel rods (the same ones used in the ZL1), and a forged steel crank. The mechanical valvetrain’s geometry started with a 302/316-degree solid bumpstick with .520 lift. The closed combustion chambers housed 2.19” intake and 1.71” exhaust special steel alloy valves with aluminized face and heads. A 780 cfm Holley four-barrel carburetor with 1.686-inch primaries and vacuum secondaries was mounted on an aluminum intake manifold with a divided plenum. All L72 Camaros received single point aluminum distributors (ZL1s used transistorized ignitions). For adequate cooling, the heavy service Harrison four-core radiator was installed. The result was 425-horsepower @ 5,600 rpm and 460 lb.-ft. of twist @ 4,000 rpm.
Cast iron exhaust manifolds dumped to 2.25” branch pipes, then to a four-chambered exhaust, using two forward and two rear chambers, then funneling out to 2-inch main and tail pipes. The F41 suspension was comprised of heavy-duty shocks and chrome carbon steel rear springs with five leaves. The stronger springs measured 56.0x2.25” with a deflection rate of 135 pounds per inch. Up front, the coil springs had a deflection rate of 320 pounds per inch, with heavy-duty one-inch diameter shocks and a .6875-inch steel stabilizer bar and harder durometer link bushings. The mandatory power front disc brakes used 11.0x1.0-inch iron rotors and single piston calipers; the rear drum brakes measured 9.5-inches with 2.0-inch wide linings. The 14x7” steel wheels were fitted with Goodyear F70x14 two-ply bias belt tires.
Either the three-speed M40 Turbo Hydra-Matic or four-speed M20 wide ratio or M21 close ratio transmission was offered. With manual transmissions, the L88 11-inch clutch was installed. All transmissions were fitted with 12-bolt rears housing 4.10:1 rear cogs (4.56:1 was optional). This was a special service 4-series Eaton positraction case including heavy duty springs, spider gears and plates. The 8.875-inch ring and pinion was heat treated and immersed in high quality oil.