Even the Chevy Raceshop engineers enjoy spending their weekends at the local boneyard. Always on the lookout for parts to recycle, this pastime carries over to their day jobs too. A recent example of in-house auto recycling is this Impala SS wagon. This ’94 Chevrolet Caprice wagon was originally a GM development vehicle equipped with the 4.3L (265ci) L99 engine and 4L60E transmission. This smaller- displacement L99, rated at 195 hp, is similar in appearance to the LT1 found in Corvettes, Camaros, and Firebirds, and it’s often called the “baby LT1.” Using GM Performance Parts to increase the small-inch motor’s output to 330 hp, the Chevy Raceshop installed this engine/trans combination in its yellow ’55 Chevy 210 (“Timeless Machine,” Aug. ’95) as a tribute to the 40th anniversary of the small-block.
The wagon then became a rolling testbed for the fuel-injected 502ci Rat that the Raceshop boys developed and later installed in a ’94 Impala SS (Motor Trend, Oct. ’94). With both of those projects behind them, Raceshop engineers Mark McPhail and Scott Leon turned their attention back to the wagon by choosing a Corvette LT4 engine tuned up with the Hot cam kit. With a revised EFI calibration and breathing through a 77mm ’94 Corvette air meter, this potent 370hp motor was installed along with a Corvette-spec 4L60E trans. Impala SS wheels and tires replaced the original rolling stock and in went a 3.23 limited-slip rear axle with disc brakes. To give the wagon a more sinister appearance, the guys installed an Impala SS hood and grille. While that helped, the roof rack and bright wheelwell trim had to go. The wagon then cruised through the GM Desert Proving Ground paint shop for a jet-black hue and was finished off with a set of red Bow Ties borrowed from the back of a ’95 Monte Carlo. The interior also received new Impala SS door panels and instrument cluster. The 60/40-split cloth front bench seat was transformed into a pair of buckets by replacing the driver seat with a second passenger seat. This gave the boys room for an Impala SS console.
Chevy High took note of this Hot Rod Power Tour veteran in San Bernardino this past June as it was poised once again to accompany the GM Motor Medics on its most recent Power Tour 2000 sprint from California to Florida. For this trip, the Impala SS wagon showed off its latest modification—a T56 six-speed conversion matched with a set of 3.73 gears.
The T56 conversion started out similarly to that of the Raceshop Blazer SS (see Get 6 With A Blazer SS: How The Chevy Raceshop Bolted A T-56 Into A Blazer/S-10, February 2000) with the installation of a Centerforce flywheel, clutch, and pressure-plate assembly. Other major components included a ’94-’97 Camaro transmission and bellhousing. The Caprice crossmember has two holes in it for a transmission mount. The 4L60E mounts in the rear hole, while the T56 uses the front. The crossmember required some additional modification since the bottom of the mount for the T56 is located 1¼-inches lower than the mount used on the 4L60E, which had been removed. Material also had to be removed from the front of the crossmember to allow room for the leading edge of the tailshaft housing. The altered crossmember was then reinstalled in its original location. Since the 4L60E and the T56 are similar lengths, the original driveshaft was reused.
Since fullsize B-cars were never factory equipped with manual transmissions, a matching clutch and brake-pedal assembly did not exist. To overcome this obstacle, the Raceshop boys (Todd Monsey, Bruce Jones, Mike Daniels, and Dennis Skutecki) modified a pedal set liberated from a ’98 Camaro. The crew located the F-car pedal assembly so that the pedal pivot was in the same location as the original B-car assembly. Then they discovered that the Caprice brake booster and master-cylinder mount were about 2¼-inches farther forward than in a Camaro. In order to use the F-car clutch master cylinder and maintain the stock geometry, they had to fabricate an adapter bracket that bridges the distance between the F-car pedal assembly and the front of the dash using the B-car brake-booster mounting bolts.
The Raceshop crew also added a switch to the starter circuit that only allows starts when the clutch pedal is depressed. A hole had to be cut in the firewall just below the booster to allow the clutch master cylinder to be installed after the pedal assembly was in place. The fluid reservoir mounts just outboard of the brake booster. The distance from the clutch master cylinder to the bellhousing is also greater in the Impala than in a Camaro, so a longer hose was necessary. A second braided stainless hose was joined to the original using a fabricated aluminum fitting.
The manual trans now needed a hole in the floor to allow the shifter spud to come through the floor, so the crew placed an F-car rubber boot over the spud and scribed an outline around the boot to a template. This created a pattern of the boot outline and inner opening that the guys transferred to the sheetmetal. Once the sheetmetal was cut to match, the boot was then installed and sealed in place. The Impala SS console also required some modifications before it could be reinstalled. An F-car console contributed its shift boot, and the crew cut a matching opening in the big Chevy’s console. After a tune-up with a little fiberglass filler and some semigloss black paint, the console was ready for service. One last modification was necessary to locate the stock Camaro shifter and ball. An aluminum spacer was fabricated, which moved the shifter ½ inch to the right. This placed the shifter in the center of the console.
As used Impala SS and Caprice models become more readily available and affordable, there is a second generation of owners out there ready to modify the big Chevrolet. Big Chevys are becoming all the rage, and with all this abundant raw material, it probably doesn’t get any easier than this.