295 hp to push the Corvette to 150 mph
instead of the 240 hp in the current
engine. He worked closely with John
Camden who was an engineer in GM’s
dyno testing center. Zora told John
he needed 300 hp so Camden and his
associates bored the engine to 307 cid.
Duntov’s new camshaft was installed
because it had a slightly lower lift, but
much higher duration. This allowed
the engine to rev to 6,500 rpm without
valve float. The cylinder heads were
ported and polished and the compres-
sion ratio was upped to 9.23:1. When
Duntov visited John in the dyno room
Camden reported the engine was pro-
ducing 305 hp. Duntov was elated and
on December 20, 1955, he recorded a
top speed of 156.16 mph with a 2.92:
rear axle. Later, he achieved a speed of
163 mph with a 3.27:1 rear axle. With
the top speed goal reached EX87/
work was complete. All of its top-speed
hardware was removed (except the fin)
and transferred onto to a 1956 Corvette
(6901) that was to compete at Daytona.
The body of EX87/5951 was removed
and installed onto a 1955 chassis
VL55S001399.
What were the results of all this
research and development that Zora
completed on this 1954 Corvette?
Duntov drove 6901 to a two-way aver-
age speed of 150.533 mph on the
sands of Daytona Beach. This Corvette
To gain access to the trunk the fin had to be removed. The rear exhaust outlets between the rear bumpers
were filled in and replaced by 1956 bumpers with exhaust outlets that were under the taillights.
Once the door is closed the driver is out
of the wind for better aerodynamics.
The precision tachometer on the steer-
ing column was the main instrument
Zora used during his speed tests.The only way to open the passenger
door with the passenger cover attached
was to reach it from the driver’s side to
pull the latch handle.Remnants of the original 1954 interior
were still inside EX87’s cabin. It was also
a secure place for Zora’s cigarettes.After the body of EX87 was added to a
1955 Corvette frame, that cars #1399 VIN
plate was added to the Corvette.A close-ratio
three-speed
manual trans-
mission
became stan-
dard in all V-8–
powered 1955
Corvettes.
EX87 was fit-
ted with one
of these early
units.The pre-
cision
Stewart-
Warner
tachome-
ter allowed
Zora to
carefully monitor the 307ci engine’s
rpm. The new “Duntov Cam” allowed the
engine to rev to 6,500 rpm.18 VETTE 19.
[FEATURE]
RARE EX87 CORVETTE