The L78 400 four-barrel generating...
The L78 400 four-barrel generating 180 hp at 3,600 rpm and 325 lb-ft of torque at 1,600 rpm was the Trans Am's standard powerplant in '78. But several performance improvements are hidden amidst the stock under-hood appearance. Modifications include increased bore and stroke, custom JE pistons, forged Eagle rods, ported 6X-4 cylinder heads, 9.7:1 compression, an XE274H Comp Cam, and 1.65:1 roller rocker arms.
Mike replaced the original intake manifold with a '72 Pontiac cast-iron unit to rid his Trans Am's engine of its emissions-related equipment. He did, however, retain the original No. 17058276 Rochester Quadrajet with an approximate airflow capacity of 800 cfm. But to meet the increased fuel demands of the high-output mill, Mike sent the Q-jet to carburetor guru Cliff Ruggles of Cliff's Q-Jet in Mount Vernon, Ohio, for professional rebuilding and recalibration.
The T/A's exhaust system consists of tri-Y-type headers produced by Tribal Tubes Headers of Napa, California, and ceramic coated by Jet-Hot Coatings in Phoenix, Arizona, and a 2.5-inch aluminized dual-exhaust system with x-type crossover from Pypes Performance Exhaust of Hatfield, Pennsylvania. Mike ultimately chose the mellow sound of Goerlich Xcelerator mufflers to quiet the healthy 407ci. But the authoritative rumble emitted from the reproduction chrome exhaust splitters tells anyone within earshot that this isn't your average smog-era Trans Am.
This Trans Am retains its original No. 1103359 HEI distributor, which uses a stock module and spark-plug wire set to transfer current from its stock coil to the R45TS Delco plugs. The mechanical advance was recurved to provide 24 degrees by 2,800 rpm, and with an initial setting of 12, total spark lead is around 36 degrees BTDC. An additional 14 degrees is available from the vacuum-advance unit for maximum fuel economy and part-throttle performance.
Owner Mike Cundiff Jr. enjoys...
Owner Mike Cundiff Jr. enjoys piloting his '78 Trans Am as much as he does C-130s. The active-duty USAF airman is currently stationed at Davis-Monthan AFB in Tucson, Arizona, but will soon relocate to Hurlburt AFB in Fort Walton Beach, Florida.
Tucson-based Townsend's Performance & Speed rebuilt the original Turbo-350 automatic transmission to withstand the additional output generated by the 407ci engine. It boasts of many internals from Hughes Performance, including Kolene steel clutch plates, Kevlar bands, and a hardened steel drum and sprag. The stock torque converter was replaced with a Hughes GM25 unit that offers an approximate stall speed of 2,500 rpm. Moser axles were intalled in the 8.5-inch 10-bolt limited-slip rear axle, and the original 2.56:1 gear set gave way to a set of 3.23 gears for improved acceleration.
This Second-Gen Firebird's suspension needed only minor tweaking to satisfy Mike's handling expectations. To that end, the stock diameter 1.25-inch-front and 0.625-inch-rear stabilizer bars were retained, but Competition Engineering subframe connectors were added to improve body rigidity. Hotchkis Performance front coil springs dropped ride height by 2 inches, and polyurethane bushings were used where possible. Mike also replaced the T/A's original 15x7-inch aluminum Snowflake wheels with a set of 15x8-inch units from a WS6-optioned car and complemented them with 235/60 and 275/60 BF Goodrich Radial T/A tires on the front and rear, respectively.
Despite conflicting information...
Despite conflicting information found in various sources, the Turbo-350 automatic was the only transmission available with the base 400ci in '78. Four-speed manual-trans availability was limited to T/A 6.6 engines only. This Trans Am's Turbo-350 has been internally modified with many components from Hughes Performance, including a 2,500-rpm stall converter. The stock shifter remains.
Another area that received upgrading was the power-braking system. All Second-Gen Trans Ams received power front disc brakes with 11-inch diameter rotors, and a common braking improvement is installing larger 12-inch units found on a number of GM vehicles. The larger diameter rotors do, however, require new spindles. So Mike pirated a pair of spindles from a large-body '79 Buick and a pair of 12-inch rotors from a 1LE-optioned Third-Gen Trans Am. Factory 9.5-inch drums remain at the rear.
The Camel-colored custom interior was restored but is largely unmodified. Mike did, however, install new seat-cover and carpeting kits and redyed the plastic trim. According to the owner, "This is an area I'm very proud of because I did the work myself, and I think it came out looking pretty good. The only thing missing is that new car smell." In addition to the standard instrumentation and Formula steering wheel, factory options include air conditioning, cruise control, power windows, pulse wipers, and a tilt wheel.
Mike tells HPP his "overall goal for the car was to be able to win some local shows as well as break into the low-13/high-12-second range in the quarter-mile." Though performance remains untested at the time of printing, in its initial showing at the April 2006 Pontiac Heaven VIII in Surprise, Arizona, the Trans Am was awarded with a Second Place finish in the best-restored class and the coveted HPP Editor's Choice award. "I was blown away by the awards," Mike tells HPP. "I really just wanted to get the car there to compare to others and learn something about showing it."
As you can see, this project...
As you can see, this project has come a long way.
Speaking generally about Second-Gen Trans Am styling, Mike says he likes "the no-holds-barred aggressive look coupled with the functional features like the spoiler and fender air extractors, even though Pontiac had sealed the shaker from '73 forward." But what he best likes about his Trans Am is "the gorgeous body styling coupled with the power of the engine and the relative smoothness of the ride," and he plans on adding only 2,000 or so nice-weather miles per year to its current odometer reading of 126,000. Although Mike feels the current state of his Trans Am is "98 percent complete," he notes that "they're never really done!"
As for the future, "I would love to find a '76 50th Anniversary Trans Am with a 455ci and T-tops," Mike says. Even though only 110 such models were produced that year, we know we'd love Mike to find one, too. After seeing how well this '78 T/A turned out, we can only imagine the result of another Cundiff project.