B
eginning in 1957, Zora Arkus-
Duntov, with the help of fel-
low engineer and three-time
Indy 500 winner, Mauri Rose,
launched an RPO parts pro-
gram unofficially known as
“racer kits.” Customers could order a comple-
ment of options that provided them with an
excellent platform for building a competitive
car. The C1 racer kits were wildly successful.
The 1963 Z06 racer kit was patterned after
the previous kits with suspension and brake
upgrades, combined with an improved L84 fuel-
injected 327 engine. Everything looked good
until the arrival of Shelby’s Cobras. Mickey
Thompson’s Z06 Sting Ray took a debut win
at the L.A. Grand Prix, but it was a default win; as
Shelby’s Cobra broke close to the end of the race.
The writing was on the wall; the 327 fuelie Z06
didn’t stand a chance.
Early in 1962, Chevrolet decided to phase out
their W-Series 348/409/427 truck engine. The
prototype Mark II made its thunderous debut
in Mickey Thompson’s Z06 Corvette at the 1963
Daytona 250 and then at the 1963 Daytona 500 in
a Smokey Yunick-prepared 1963 Impala. The auto-
motive press dubbed the cars “Chevrolet’s Mystery
Motor.” Between Duntov’s antics at the Sebring
Grand Sport testing, followed by the press clamor-
ing over the Mystery Motor Chevrolet race cars,
GM President, Frederick Donner made it clear;
there will be no Chevrolet involvement in racing.
Development on the big-block engine for pas-
senger car use continued. A Mark III big-block
project using tooling from Packard was considered
and rejected. The Mark IV went into production
in mid-1965 as the Turbo-Jet 396. The under-
rated 425-horsepower L78 396 big-block Corvette
option hit the street in spring of 1965 costing just
$292, whereas the 375-horsepower fuelie cost $538.
Duntov compensated the extra weight with stiffer
springs, shocks and sway bars. He immediately
went to work on the L88 racer kit.
The L88 package was an all-out race car. The
430-horsepower rating was bogus; 560 horsepower
is more accurate, and good for 640 horsepower
with open headers. The aluminum heads saved 75
pounds from the front end and slightly lowered
the car’s center of gravity. With 12.5:1 compression,
103-octane fuel was mandatory. The dual-plane
aluminum intake manifold was modified to create
a plenum chamber beneath the 850-cfm carburetor.
The big carb was fitted with a unique air cleanerUnrestricted power was the L88’s end game. The L88 was seriously
under-rated at 430 horsepower; 560 was more like it with stock exhaust
manifolds; 640 horsepower was easy with headers. This was fantastic
power in 1967.VETTEWEB.COM 43