1979 Trans Am Engines: A Deep Dive into Power

The 1979 Pontiac Trans Am stands as an undeniable icon of American muscle, a symbol of an era where raw power met distinctive styling. Enthusiasts often ponder the specifics of its production, particularly the total number of units built in that pivotal year. While this particular technical guide doesn't detail the exact production figures for the 1979 Trans Am, it delves deep into the very essence of what made these vehicles so special: their engines. From their diverse origins to the intricate process of their restoration and rebuilding, understanding the powerplant is crucial for any Trans Am owner or admirer. This article aims to illuminate the fascinating world of Trans Am engines, offering vital insights into identification, maintenance, and the rewarding journey of bringing these mechanical marvels back to their former glory.

The second-generation Pontiac Firebird and Trans Am, produced from 1970½ to 1981, saw a remarkable array of engines slotted into their engine bays. Initially, these cars were pure Pontiac, featuring the robust 400- and 455-cubic-inch V8s that defined the muscle car era. These were engines designed to spool out a significant amount of torque, making them ideally suited for spirited street driving and contributing to the well-rounded and fun driving package Pontiac was known for. However, as the years progressed and automotive landscapes shifted, so too did the engine offerings.

The Evolution of Trans Am Powerplants

The early years of the second-generation Firebird were dominated by Pontiac's own V8s. The 400 Ram Air III and IV, along with the mighty 455 Super Duty engines, were the powerhouses that cemented the Trans Am's legendary status. These high-performance engines, when fitted, command the highest values in today’s collector market. Yet, even the more common V-8 Firebird and Trans Am models are certainly worthy candidates for a meticulous rebuild, testament to their enduring appeal and solid engineering.

A notable shift occurred in 1977 with the introduction of the 403-cubic-inch Oldsmobile engine. While technically a big-block, its output of a mere 185 horsepower was a stark contrast to the earlier Pontiac giants. Coupled with a 2.56:1 rear axle ratio and a hefty curb weight exceeding 3,800 pounds, it wasn't exactly a stoplight terror. This change reflected the growing pressures on manufacturers to meet fuel economy standards.

Further diversification came with the 301 light-cast engine, an effort explicitly aimed at improving fuel efficiency. The turbo version of the 301 made its debut in 1980, following the discontinuation of the 400 in 1979. The 305 Chevrolet engine also became an option in 1980 and 1981, marketed as a performance alternative. Identifying these various engines often came down to subtle visual cues, such as the long oil fill neck on the Oldsmobile engine.

Interestingly, the iconic shaker hood scoop, a signature Trans Am feature, bore different decals depending on the engine. Originally, a Pontiac 400 engine would see the shaker labelled as a 'T/A 6.6', while the 403 Oldsmobile engine received a '6.6 Litre' decal. However, replacement decals over the years have led to inconsistencies, meaning the shaker callout alone isn't always a reliable indicator of the original engine. For accurate identification, enthusiasts relied on the VIN designation, where 'K' indicated a 403 Oldsmobile engine and 'Z' denoted a 400 Pontiac engine.

Engine Type Overview and Characteristics

Deciphering Engine Identity: A Crucial First Step

Given that many Firebirds and Trans Ams have lived demanding lives, it's common for them not to possess their original engines. Abuse, neglect, or internal component failure often led to engine swaps or the installation of service replacement blocks. Therefore, accurate Engine Identification is paramount before embarking on any rebuild project.

For Pontiac V-8s, the block casting number can be found at the rear edge of the block, behind the passenger-side cylinder bank. The date code and the last two numbers of the year are located near the distributor hole, at the back of the block near the driver-side cylinder bank. The block code, which indicates the engine and application, is on the front, below the passenger-side of the head. It's crucial to remember that these block codes were often reused annually, so a 'YZ' code in 1970 (a 400-ci Ram Air III 345-hp engine) is vastly different from a 'YZ' code in 1972 (a 400-ci 2-barrel 200-hp engine). For a definitive check, the VIN located on the engine pad near the lower pulley is the final piece of the puzzle.

For Firebirds equipped with the 403 Oldsmobile engine, the VIN and casting number are in different locations. The VIN is on the driver's side of the block front, just below the head and behind the power steering. The casting number is on the top of the engine, just behind the oil filler tube. In 1979, the Olds engine code was even placed on the driver-side rocker cover on a bar-coded label, further complicating identification for the uninitiated.

Rebuilding Considerations: DIY or Professional?

The Pontiac V-8 engine platform enjoyed remarkable interchangeability, with heads, intakes, internals, and exhaust manifolds often swapping easily between 350, 400, and 455 cubic inch variants. While this offers flexibility, it also means many engines may have non-original parts. Before undertaking a Rebuilding project, an honest assessment of one's mechanical ability, workshop space, and available tools is essential.

Most mechanically inclined car owners can competently rebuild an engine, especially if they adopt a thorough and methodical approach. However, critical machining work, such as crank straightening or cylinder boring, must always be handled by a qualified machine shop. For exceptionally rare and valuable engines, such as the 400 Ram Air III, 400 Ram Air IV, or the 455 Super Duty, professional rebuilds by specialist shops are highly recommended. If you're new to engine rebuilding, the learning curve can be steep, making a professional engine shop with specific experience in Pontiac V-8s a safer and often more cost-effective choice in the long run.

It's also important to remember that not all engines in Trans Ams are original. Service replacement engines were often installed under warranty, meaning block numbers might not match VIN numbers. Aggressive driving and neglect, common for muscle cars, also led to engine failures and non-original swaps. Properly identifying the engine under the bonnet is therefore the first critical step before any rebuild plan can be formulated.

When to Rebuild and What to Expect

Signs that an engine needs a rebuild can be obvious: blue smoke from the exhaust, knocking sounds, white smoke, or a seized engine. Less obvious signs, like low compression despite seemingly good running, can be diagnosed by a compression test or leak-down test performed by a reputable shop. While some engines run perfectly well, they might simply be worn out and in need of an overhaul.

Choosing to rebuild an engine yourself versus sending it to a professional shop involves weighing expertise, specialty tools, and the value of a warranty. Professional shops specialising in Pontiacs offer invaluable experience due to the unique characteristics of these engines. Furthermore, a warranty on a professional rebuild provides peace of mind, especially given that modern replacement parts can sometimes be of dubious quality. Even a minor part failure can have catastrophic consequences, making the investment in a professional rebuild often worth it.

The Rebuilding Journey: A Step-by-Step Overview

The process of rebuilding an engine is time-consuming and meticulous, demanding Patience and organisation. Here’s a general overview of the steps involved, from removal to reinstallation:

1. Engine Removal: Disconnect the battery, all coolant hoses, transmission lines, engine accessories, vacuum lines, fuel lines, and electrical connectors. Drain the engine oil. Remove the A/C compressor and power steering pump. Disconnect fuel lines and exhaust head pipes. Remove motor-mount and transmission bellhousing bolts. Use an engine crane, attaching a chain to the water pump eye and the rear intake manifold, or use a dedicated plate that bolts to the intake manifold. It's often easier to remove or at least disconnect the transmission before lifting the engine clear of the vehicle.
2. Linkage Disconnection: Carefully detach throttle linkage (secured with a washer and cotter pin), kick-down linkage (if equipped, pops off and held by a spring clip), and the shaker solenoid actuator (single connector, open-end wrench).
3. Mounting on Stand: Once removed, install the engine onto an engine stand. This provides stable access for the rebuilding process. For larger engines like the SD 455, a four-wheel engine dolly can be useful for transport.
4. Machine Shop Work: Send the engine components to a qualified machine shop. If you want the heads milled and port-matched, send the intake and exhaust manifolds as well. Porting and polishing the heads is highly recommended for Pontiac engines, as much of their power is made here. Late 1970s 6X heads, for instance, can be made to flow as well as Super Duty heads with proper work.
5. Engine Painting: After the engine returns from the machine shop, degrease it thoroughly to prepare it for paint. Pontiac engines were painted many different shades of blue over the years (e.g., Pontiac Blue, Pontiac Blue Metallic, GM Corporate Blue). Apply a high-temperature primer, paying attention to the hot spots like the centre exhaust ports.
6. Hardware Cleaning and Painting: Clean and repaint all removed hardware before reinstallation. This attention to detail contributes significantly to the engine's restored appearance and longevity.
7. Manual Transmission Components (if applicable): If your vehicle has a manual transmission, install the flywheel, clutch, clutch fork, throwout bearing, and bellhousing before reinstallation. Consider tubular ceramic-coated headers for added Performance and reduced under-bonnet temperatures.
8. Engine Installation: Position the engine using a hoist. This is ideally a two-person job, with one operating the hoist and the other guiding the engine into place and aligning the motor mounts. Exercise patience to avoid damaging the firewall or other components.
9. Final Connections: Once the engine is securely in position and motor-mount bolts are threaded, reconnect all throttle linkage, coolant hoses, electrical harnesses, and other previously disconnected parts. Replacing all hoses, mounts, and clamps at this stage is highly recommended to prevent future failures.

Original Appearance and Numbers-Matching

For collectors and purists, maintaining the original appearance of the engine is key. Pontiac engines, while not flashy, were all about performance. Restoring them requires meticulous attention to detail, including correct engine colours. Pontiac changed engine colours several times throughout the Firebird's run: 1971–1973 used Pontiac Blue non-metallic, late 1973 and 1974 used Pontiac Blue, 1975–1977 used Pontiac Blue Metallic, and 1978–1981 used GM Corporate Blue. Even the valve covers varied, from chromed versions on early Ram Air engines to engine-coloured ones on SD 455s. These paints are available from specialist suppliers.

The decision to rebuild your existing engine versus replacing it often hinges on whether your Firebird has a Numbers-Matching engine. If it does, rebuilding it is generally the wisest choice for value and authenticity. If you plan to drive the car hard, some owners opt to store the original engine and rebuild a different Pontiac engine for regular use. Another increasingly popular route is the 'resto-mod' approach, which involves installing a modern Chevrolet or LS engine for enhanced performance and reliability, though this deviates from original authenticity.

A 'correct' engine is an original-displacement engine with correctly coded block and heads that came with your car, with component dates falling within two to three months of the car's build date. It may even be a service replacement block, but it should otherwise replicate the original. Any other type of replacement engine is not considered numbers-matching. It's not uncommon to find stroked 400-ci or 455-ci engines in Firebirds today, offering significant power upgrades.

Frequently Asked Questions (FAQs)

Q: Is it difficult to rebuild a Trans Am engine yourself?

A: While a competent mechanical inclination is helpful, rebuilding an engine for the first time is a steep learning curve. The machining work requires professional shops. For rare or valuable engines, professional rebuilds are highly recommended. However, with a methodical approach and attention to detail, a capable DIY enthusiast can undertake a rebuild.

Q: How do I know if my Trans Am engine is original?

A: Identifying an original engine requires cross-referencing block casting numbers, date codes, block codes, and the VIN located on the engine pad. Be aware that block codes were reused over years, and service replacement engines were installed, meaning block numbers might not match the VIN. Consult comprehensive guides for detailed identification procedures.

Q: What are the signs that my engine needs a rebuild?

A: Obvious signs include blue or white smoke from the exhaust, knocking sounds, or a seized engine. Less obvious signs, like low compression, can be detected through compression or leak-down tests performed by a workshop.

Q: Can I upgrade my Trans Am engine for more power?

A: Absolutely. Numerous performance parts are available for Pontiac, Oldsmobile, and Chevrolet engines, especially the 400 and 455 Pontiac variants. Port matching, carburetor tuning, distributor advance, and exhaust sizing improvements can yield significant gains. Stroker kits are a popular internal upgrade that boost power while maintaining an outwardly stock appearance.

Q: Are parts readily available for all Trans Am engines?

A: Parts for Pontiac 400, 455, and Oldsmobile 403 engines are generally available from performance retailers. However, parts for the 301 and especially the 301 Turbo engine are notoriously difficult to find, with performance upgrades almost non-existent for the latter.

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