When you think of the name Thumper, is the first image that pops to mind of a cute, cuddly, and furry bunny rabbit friend of Bambi? Well, you can quickly forget that Disney cartoon character and meet the new Thumper-a bad-to-the-bone, race-prepped, street-legal '78 Corvette with a big-block and LOTS of attitude!
When Dr. G.R. Richards of Lubbock, Texas, purchased his '78 bubble-back coupe over the Internet a couple years ago, it was already a mild hot-rod with a 383-cid stroker small-block and a Turbo 350 automatic, and it had lots of chrome under the hood. After the car made its journey from Southern California to its new home in northwest Texas, though, Dr. Richards soon realized that the Vette wasn't everything he wanted as it was. The ill-tempered 383 was hard to start and didn't run well, plus the Shark just didn't handle like a Corvette should due to an awkward, "nose-in-the-air attitude." It only took a few weeks before he called up Scott Arnold at Scotty's Vettes in Dickens, Texas, to remedy its vices. Because Scotty's shop was already in the middle of a couple major builds, they couldn't start on the '78 project at once, but Dr. Richards had another Vette to drive. So the '78 sat on the rear burner for a while.
Over the following year, Scotty and the good doctor came up with a wild but moderate game plan for the '78. Impressed by a radical big-block '63 split-window project that Scotty had just finished, Dr. Richards asked him to replace his 383 small-block with a brand new ZZ502 big-block crate motor. Scotty agreed to this new project and prepared to build an "average" big-block 502 street machine when Dr. Richards changed his mind. Can too much ever be enough? Obviously not when you're talking about anything in Texas where bigger is always better. Richards soon decided that a mere 500-horsepower big-block wasn't enough, so he called Scotty back a week later and pulled out all the stops.
Instead of the GMPP crate motor, the doctor had to have the seriously built 548-cid monster motor he'd seen in the back room of Scotty's shop that was slated for another project. Why settle for 500 horses if you can get 790! Dr. Richards was undaunted by the fact that much more would have to be done to the '78 for it to withstand yet another 300 horsepower (basically the equivalent of adding an additional small-block engine!), but he instructed Scotty not to change out the chassis and to keep the noise "down to a low rumble." Thus, with all that in mind, Scotty dove into the ever-expanding project to build one extremely bad street Shark-which became nicknamed Thumper!
Scott and his partner Mike began by pulling the small-block and trans out and scoping out the immense amount of fabrication necessary. Scott reinforced, cut, and boxed the frame for clearance; lowered the front suspension with Monroe gas shocks and Bell springs; added a Hotchkis front anti-roll bar, and converted the steering to a Speed Direct Steeroids rack-and-pinion system. The rear suspension received Bilstein gas shocks, and strengthened half-shafts were connected to the 3.73:1-geared third member.
Scotty managed to make the huge motor look like a natural fit in the tight confines of the late C3's engine bay, but wedging it in there was anything but easy. "We installed the engine with moderate difficulty and with mods that edged on the extreme," Scotty tells us. "The oil pan would not work with the rack-and-pinion, and the valve covers would not work with the A/C box, nor would the vacuum booster be able to stay. So the oil pan was changed, and the vacuum booster was history." It took a bunch of reengineering to make everything fit, but the big-block now sits happily perched upon its Moroso solid motor mounts.
Sunset Racecraft in Lubbock, Texas, built the huge-displacement, 790hp powerhouse that Scotty and Mike shoehorned into Thumper, starting with a machined Dart Pro-1 548-cid big-block with Dart Pro-1 ported and polished aluminum heads. They fortified its innards with a steel crankshaft, SP 11.5:1 compression pistons, Clevite bearings, and gold roller rockers. The motor, which is dressed-to-kill in a black satin aluminum finish, is decked out with natural aluminum Merlin valve covers, an Edelbrock Victor intake, and a massive 1,150-cfm Holley
Dominator carburetor. A complete MSD ignition system fires the 548, including an electronic billet MSD distributor, MSD Blaster coil, MSD wires, and MSD 6AL box.
March Performance pulleys spin the accessories that are mounted on custom billet and handcrafted brackets, including a black-satin-finished 100-amp alternator and a Sanden A/C compressor. Since there wasn't enough vacuum from the engine for headlamp actuation, Scotty replaced the vacuum system with a set of electric linear actuators-which "work smooth and are quiet, and are not as violent as the originals." Scotty made the necessary modifications to make a high-capacity 8.5-quart oil pan fit around the steering rack, and he employed a Melling sump pump to lube the motor.
To cool the big-inch engine, Scotty chose an Edelbrock aluminum water pump and a large polished Be Cool radiator with a Be Cool electric module. Scotty installed a custom-fabricated stainless steel fuel cell from RCI with a sending unit and vents, along with a Holley Red electric fuel pump and BG fuel filter to feed the carb at a regulated 7.0 psi. The battery was relocated to the back of the car, so the high-voltage yellow-top Optima battery needed to juice this hellacious Corvette, no longer hangs near the RCI tank.
Hedman 2.5-inch headers wearing Thermotech heat wrap dump spent gases into the custom 2.75-inch exhaust that was fabricated by Joe at A&B Muffler and Brake Shop in Lubbock Texas. Dr. Richards specified that Thumper must be quiet enough to drive across town to the hospital at 2:00 a.m. if necessary, so Joe muzzled the big motor's thunderous bark to a low rumble using two pairs of mufflers-passing first through a pair of Magnaflows and then a pair of Flowmasters.
Considering the engine cranks out nearly 800 horsepower, losing approximately 60 ponies to make it civilized enough for Doc Richards' driving chores really is just a drop in the bucket. The meager 730 or so horsepower that remains is channeled through a GM Performance Parts lightweight flexplate and a strengthened Sullivan Turbo 400 transmission with a 2,500-rpm TCI torque converter and a billet B&M shifter.
Scotty and Mike gutted Thumper's interior with visions of a "full-on comp look" to replace it. They began with safety by selecting Kirky racing seats, G-Force Racing Gear five-point harnesses, and a CE roll cage kit. "The original dash was cracked and the door panels were ragged, but there was room to get everything together," Scotty says. So they fabricated a custom aluminum-paneled dash which houses a full array of Auto Meter Ultralite gauges, a high-tech Sony MEX-5DI MG-MS/FM/AM CD Player, the factory A/C controls, power window switches, toggle switches for the fuel pump, and a pre-wired NOS cutoff ("just in case" wretched excess is not enough!).
Scotty took Thumper to an upholstery shop for custom door panels with flame work and new carpeting, but that turned into a fiasco. When Scotty came back to collect the Vette, the shop was still not finished and time was of the essence. "By the time they were finished, the door panels weighed 20 pounds and looked thick, and the carpeting was not done as directed," reports Scotty. "On a rainy weekend, the door panels started to come undone and I was mad about the carpets. So I ripped everything out of the car and reworked it all myself!"
The entire interior is upholstered in black tweed and velour. Scotty handcrafted his own custom door panels with raised flames, as well as covering the T-top headliners with matching flame work. The dash and all paneling are covered by tweed. A pair of high-output amps are mounted on the back wall of the rear storage area-powering a pair of two-way speakers in the dash, two three-ways in the kick panels, and a pair of killer subwoofers mounted in the storage compartments behind the seats. Scotty rewired the entire car, adding a master cutoff switch on the floor of the rear between the subs. A purposeful, leather-wrapped custom steering wheel tops off the not-quite business-as-usual cockpit.
The exterior of the '78 was in respectable condition before the project began, already wearing a full line of Ecklers ground effects, including side skirts, a front air dam, and rear bumper with a lip spoiler. It also sports Ecklers bubble taillights. But, when Thumper came to be, "presentable," it was no longer good enough! A custom hood was required to provide more clearance space for the big-block, and since there isn't a wide variety of aftermarket hoods available, Scotty decided to build his own.
They crafted a functional, 3.5-inch raised cowl-induction hood, which sucks air in from the back through a pair of customized K&N filters and feeds it directly into the Holley carb. Once the hood was created, Scotty molded the Ecklers ground effects to the body, and he spent hours block-sanding the whole car. Gilbert at Finish Master stirred up a custom bright red PPG paint for Thumper, and Scotty shot the Vette with PPG DBU base and PPG 2042 clear before color-sanding and buffing it to a brilliant gleam. A set of billet 17x8 and 17x9.5-inch Boyd Coddington rims finish off Thumper's eye-grabbing appearance.
Dr. Richards' race-prepped street machine just radiates attitude and presence. Even though Thumper is discreetly quiet, there is no missing the fact that this Shark is not to be messed with. Few boy-racers in their Hondas or Mustangs will ever quibble about Thumper's right to be Top Dog on the streets of Lubbock, and boy will they be sorry if they do! This Thumper is certainly not cute and cuddly like Disney's cartoon character, but the sheer, wretched excess of the '78 gives us some serious warm-fuzzies!