I knew all too well. Nevertheless, I could see that a new obsession was being hatched as we stood there. I should have remembered that Imran is a doer. This guy makes things happen-big time. With him, there is no other option besides all the way.

As usual, I'm getting ahead of myself, so let's get into the background.

The Stillborn Super-Duty GTO

For longtime Pontiac fans, the story of the legendary Super-Duty 455 was one like many others from the Wide-Track Division, it held so much more promise than it was allowed to deliver. During the early '70s, the triple-whammy of rising insurance prices, a new wave of emission regulations, and the Arab Oil Embargo made the promotion of musclecars about as politically correct as a KKK family cookout. It seemed like everyone was jumping on the bandwagon, trading in their GTOs, Cobra Jets, and Super Sports for Plymouth Crickets, Ford Pintos, and Datsun B210s. Talk about dark, misguided times.

Pontiac was in a particularly tight bind, as its marketing strategies in the late '60s depended on street performance, and that notion had placed it firmly in the crosshairs of several groups bent on making the world safe from the evils of Ram Air and four-on-the-floor. Still, PMD engineers were doing their level best to cater to the needs of their target market, despite the fact that they were quickly losing favor with a new management regime.

The need to comply with low-lead and no-lead fuel gave rise to the 455 H.O., which took over where the Ram Air IV had left off. Performance remained, and even took a small step forward despite the odds, as the larger-but-milder 455 H.O. 's broad torque curve actually made the '71 GTOs a little quicker than the high-strung Ram Air IV. Always against the odds, Pontiac's rebellious underdog image was preserved a bit longer.

Fortunately for performance buffs, Pontiac's Special Projects had one more trick up its collective sleeve before the catalytic converter came in and finished off the era. In the spring of 1972, Pontiac held a press conference at its '73 long-lead media event announcing the release of a limited-production, purpose-built race engine that was detuned somewhat for street operation, yet would give privateer racers a very solid basis for competition use. Known internally by such nicknames as "Hemi Hunter" and "Rat Eater," it was officially dubbed the 455 Super-Duty, calling to mind the legendary Pontiac factory racing program of 1960-1963. They even had cars at the event capable of low 13s at 105 mph.

To say that the enthusiast press was excited was the understatement of the year. In an age of tape-stripe performance and phony mag wheels, the 455 Super-Duty was like a bucket of cold water over the head-it was the real deal in a sea of poseurs.

Pontiac engineers had addressed the weak points of the Pontiac V-8 engine and corrected them. The block featured four-bolt mains, of course, and was reinforced with lifter bracing to prevent splitting down the middle. Forged rods and pistons replaced the weaker cast units used for years, and the crankshaft, while cast, featured rolled fillets for improved strength and crack resistance. Even the oiling system's shortcomings had been addressed, and there were provisions cast in the back of the block for a dry-sump to be added. As we said, it was a real race engine.

Like the short-block, the top-end received some critical improvements from the 455 H.O. The round-port heads were enlarged for a consistent cross-sectional area, this change coming from data acquired from the 303 Trans Am and 366 NASCAR programs. A cast-iron, big-port intake manifold was topped off with a special 800-cfm Quadrajet, and exhaust gases were expelled through high-capacity cast-iron exhaust manifolds.

After looking for the best combination of performance and emissions, a special version of the 301/313-degree duration Ram Air III camshaft (stamp "K") was eventually settled on, this one using a smaller distributor gear to coincide with the larger gear used on the distributor to reduce spark scatter.

The end result was an engine rated at 290 SAE net horsepower at 4,000 rpm and 395 lb-ft of torque at 3,600. While that figure might not sound all that impressive by today's standards, it was de-emphasized somewhat and rated at a lower-than-peak rpm level. Though it only had an 8.4:1 compression ratio, a myriad of emission control devices, and a fairly mild cam, it was still one of the most powerful engines of the classic musclecar era.

Timing is everything though, and the time wasn't right for the SD. With the cost of recertifying all of Pontiac's V-8s after the EPA found timers on the EGR valves that would render them inoperative after the duration of an emissions test, Pontiac limited the availability of the engine to the Firebird Formulas and Trans Ams. The widespread availability of the 455 Super-Duty in LeMans, GTO, Grand Prix, and Grand Am models was promised in early sales brochures, but never actually happened.

As it turned out, the '73 GTO was offered with the garden-variety 400 and 455 D-port powerplants, and production plummeted to 4,806 units. The aforementioned timing problems, as well as the internal competition from the new Grand Am, further reduced demand for the GTO.

Sizing Up The Project

Though he is someone who can make the impossible look easy, Imran is not one to blindly jump into a project. With this new direction in mind, he sought every bit of information he could find on the '73 GTO prototypes. He got on eBay and started buying up every magazine that even mentioned the '73 455 Super-Duty GTO, including the legendary April '73 issue of Hi-Performance Cars magazine that boldly proclaimed the 455 SD GTO its "Car of the Year." He also located and purchased factory literature and a service manual. He pored over the grainy black-and-white photos and diagrams to learn every detail possible on the prototype and put together a plan for the restoration's new direction.

Several people also provided information for the project. The late John Sawruk came through with a variety of details and specifications; and the writings of Tom Nell and Tom Goad also came in very handy. HPP's own Rocky Rotella and yours truly provided intake manifold research, Ram Air information, and other tidbits.

Drivetrain Build

From the onset, Imran had envisioned this GTO as the spiritual successor to the prototype that was featured in Hi-Performance Cars magazine and elsewhere. That meant that the engine would be built to the original 455 Super-Duty specs, not to the production version. This allowed him to include stuff that had been eliminated due to the emission certification.

The intake manifold is one area where the prototype was outfitted differently than a production version would have been. The Hi-Performance Cars magazine test car was outfitted with the No. 485640 aluminum intake manifold.

A handful of these intakes were cast but rejected for production due to their lack of heat retention, which negatively affected emissions. It was replaced with a cast-iron version for the production Formulas and Trans Ams, and the castings on hand were put into the parts network. Imran was fortunate enough to actually find one of these rare intakes and included it in the engine build.

Secondly, the engine could make use of the Ram Air IV's 308/320-degree camshaft profile and 1.65:1 rockers, which would make a huge difference in overall performance. PMD Special Projects engineers knew the secret of the 455 SD's performance was the camshaft. Many of them were frustrated and disappointed that the "big" cam couldn't be used in production. Imran's engine would employ this critical element and benefit from the additional duration and 0.520-inch lift. The actual cam featured the correct cam gear and was from Melling, an OE supplier to Pontiac.

The engine was machined and balanced by Gerry Bartel at The Balancing Act and was assembled by Imran. Its block was bored 0.030 over and fitted with Keith Black 9.5:1 forged pistons with Total Seal moly rings. Federal Mogul bearings were used for the mains and rods. The rest of the engine was stock, including the correct 455 SD high-volume oil pump. Per the Pontiac Service Bulletins of the time, the galley plug near the distributor had a 0.030 inch drilled in it to lubricate the distributor gear. This modification also dropped the oil pressure from 80 to a more reasonable 60 psi.

Imran went the extra mile for authenticity, managing to find correctly date-coded NOS spark plug wires and AC spark plugs in their original boxes. He even managed to find a correctly date-coded AC oil filter. The engine was painted as it would have been with an early '73 release-the light blue that was used starting in 1971. Engines built after March 15, 1973, used a darker blue, indicating the revised emission control system. Talk about sweating the details!

As expected, the finished engine was quite a bit healthier than the production SD-455. With just the cam change, 1.65 rockers, and aluminum intake manifold (which may or may not have a noticeable effect on power), the big SD responded on the SuperFlow dyno with 415.3 hp at 4,800 rpm and a whopping 514.7 lb-ft of torque at 3,500 rpm. The potential of the Super-Duty, even with the low compression, is very impressive.

Additionally, the pre-production prototype was equipped with a four-speed manual transmission, and this GTO was built as an automatic. A conversion to four-speed certainly wasn't out of Imran's capability, but getting the necessary parts was a huge task. The majority of the componentry came from a locally sourced '73 four-door Grand Am, one of the 187 four-speed cars built and perhaps 1 of 20 four-doors. Unfortunately for that particular car, it was rusted far beyond salvaging, but it did provide the pedals, linkages, shifter, and console. Imran went with a Borg-Warner Super T-10 out of a late '70s Trans Am rather than the Muncie M20 specified for production.

Out back, the original rearend was rebuilt and fitted with 3.42 gears and a Safe-T-Track. The correct steel wheels and baby-moon hubcaps are set off with a set of reproduction G60-15 Goodyear Polyglas GT tires.

Conclusion

What is next for Imran and his one-of-zero-built 455 Super-Duty '73 GTO? "Now that I have the show awards, I really want to drive this one a bit," he replied. "It has a very powerful engine, yet it's also very docile. It idles at 600 rpm, and you can set a glass of water on the air cleaner and it won't move."