If you've ever contemplated restoring a C4 Corvette and received a chilly reception from your family and friends, consider directing them to the Corvette C4 Guru Forum (www.c4guru.com). The site dedicates itself to the preservation of the '84-'96 Corvette, with an extensive tech library, videos, forums, RPO codes, data sheets, specs, and more.
Casey Webster, a 27-year-old maintenance technician from Sippy Downs, Queensland, is a moderator of the site and one of its online gurus. "I love Corvettes," he says. "I've been driving Vettes since I was first licensed. When I was 17, I worked almost 60 hours a week to get my first one, an '87 coupe. In the past nine years, I've pulled apart almost every single area of a C4, so I've got a fair amount of experience with them."
An L98 '87 Corvette was a great introduction into the hobby for Webster, but he knew he wanted a bigger slice of performance. That extra urgency debuted in the Corvette in '92, in the form of the Gen II LT1 engine. In 2001, he purchased an Arctic White '94 coupe that had immigrated to Australia after the end of the C4 era.
Like most of the 4,066 Arctic White Corvettes that rolled off the Bowling Green assembly line in '94, Webster's Corvette was equipped with an LT1 engine and a four-speed automatic transmission. Output was rated at 300 hp, an increase of 60 hp over the '87 model. The base price was $36,185.
"The '94 had a lot of work done on it, so I didn't have to worry about being the one that modified a perfect, original car. But it needed a lot of work, too, and I knew I could do all that work myself and save a lot of money," says Webster.
Because the paint was (surprisingly) factory original, Webster focused first upon the car's mechanicals. He commissioned a 4L60E trans rebuild from Adams Automatics of Caloundra, Queensland, and then corrected the C4's few existing flaws by repairing the pop-up headlight assembly and swapping the rubber suspension bushings for polyurethane units.
Next, Webster removed the interior trim and lathered the inner surfaces of the body shell with DynaMat Extreme sound-deadening material. He reinstalled the thrones-now resewn with black leather and accented with white welting and embroidery-and reused the original panels and carpet. He was saved the expense of a government mandated right-hand-drive conversion (required on all imported LHD cars fewer than 25 years old) because the Corvette had already been modified to RHD by a previous owner.
Webster's next step was to darken the sidemarker and taillights, after which he turned his talents to the engine compartment. He replaced the original water pump and heater core, citing "previous owner neglect" as the cause of their failure. He then spent several days performing diagnostic testing and data-logging, eventually tracing a hesitation problem to a blown head gasket. He removed the heads and sent them to Iain Woodward in Brisbane for CNC porting. At the same time, he sourced new gaskets from Don MacLeod of Maxx Wrench in Burlington, Colorado.
In reassembling the motor, Webster stayed with the stock displacement of 350 cubic inches, also retaining the LT1's cast-iron crank, powdered-metal connecting rods, and hypereutectic-aluminum pistons. The freshened aluminum heads were returned to him ready to rock, with Crane Gold 1.6-ratio rockers, Crane 99838 springs, 2.02/1.60 valves, and new factory pushrods. He installed a Crane hydraulic roller cam with 222/230-degree duration and 0.509/0.528-inch lift on a 112-degree lobe-separation angle. The compression ratio was bumped from 10.4:1 to 11.0:1.
The air-induction system features a GM air lid, a K&N filter, and a ported 48mm GM throttle body. An OptiSpark distributor ("It's an exceptionally good system and gets a lot of ridiculous unfair criticism," says Webster) directs spark down 8mm GM wires to NGK Iridium TR55IX plugs. Premium fuel flows from a 255-lph factory pump to 30 lb-hr Bosch injectors installed in a ported factory intake. Exhaust gases are evacuated through "tri-Y" long-tube headers with 1 3/4-inch primaries, 2-inch secondaries, 3-inch collectors, twin highflow stainless converters, Genie stainless mufflers, and 3-inch pipes.