1973–1977 Pontiac Grand Prix SJ — Fourth-Generation Colonnade Icon
The fourth-generation Pontiac Grand Prix SJ represents the personal-luxury coupe at its American zenith: a long-hood, short-deck two-door that balanced comfort and credible GT tuning. Launched for 1973 on GM’s new “Colonnade” intermediate architecture, the SJ sat atop the Grand Prix range as the driver-focused specification, typically aligning the biggest available Pontiac V8s with stiffer suspension, uprated rubber, and full instrumentation.
Historical Context and Development Background
For 1973, General Motors reorganized its intermediate line around stronger roof structures and federally compliant energy-absorbing bumpers. Pontiac’s Grand Prix, already a sales force from 1969–1972, was re-proportioned into the Colonnade template alongside Monte Carlo, Cutlass Supreme, and Regal/Century—sharing core A-body underpinnings while asserting Pontiac character. The styling—developed under GM Design’s Bill Mitchell era—kept the marque’s pointed “beak,” split grille, and an elegant formal roof with small opera quarter windows. Inside, the signature engine-turned dashboard fascia and deep-set round gauges remained a brand calling card.
Corporate priorities in the mid-1970s were shifting: emissions controls, fuel economy, and crash regulation marched in, while the market moved toward plush, quiet coupes with just enough verve to feel special. The SJ package was Pontiac’s answer—Radial Tuned Suspension (RTS), firmer shock valving, heavier anti-roll bars, performance-oriented tires, and a comprehensive gauge cluster lived here, often paired with the 400 or 455 four-barrel. While the Grand Prix name had been used in stock car racing before, the 1973–1977 body style saw limited yet notable oval-track presence relative to Chevrolet’s Laguna S-3 and Monte Carlo; Pontiac buyers were more likely to meet an SJ prowling the interstate than on a superspeedway podium.
Competitively, the Grand Prix SJ sparred with Chevrolet’s Monte Carlo Landau, Oldsmobile’s Cutlass Supreme Brougham, Buick’s Regal, and later, Chrysler’s Cordoba and Mercury’s Cougar XR-7. Pontiac positioned the SJ as the enthusiast’s personal-luxury choice—decisively more athletic than the class average yet never harsh.
Engines and Technical Specifications
The SJ’s heartland was Pontiac’s own V8 family, with displacements spanning 301, 350, 400, and 455 cubic inches through the cycle. The 455 four-barrel was the flagship through 1976 in many markets; by 1977, the 400 took the performance mantle while the newly introduced 301 served as the frugal base in several applications. Output varied by year, emissions calibration, altitude, and market. The table below summarizes representative configurations seen in Grand Prix SJ fitments or the broader 1973–1977 Grand Prix range.
| Engine | Configuration | Displacement | Horsepower (net) | Induction | Redline | Fuel System | Compression | Bore x Stroke |
|---|---|---|---|---|---|---|---|---|
| Pontiac 455 V8 (4-bbl) — 1973–1976 availability | 90° OHV V8, iron block/heads | 455 cu in (7.5 L) | ~200–250 hp (year/market dependent) | Naturally aspirated | ~5,000 rpm | Rochester Quadrajet 4-bbl | ~7.6–8.0:1 | 4.152" x 4.21" |
| Pontiac 400 V8 (4-bbl) | 90° OHV V8, iron block/heads | 400 cu in (6.6 L) | ~180–230 hp (year/market dependent) | Naturally aspirated | ~5,000 rpm | Rochester Quadrajet 4-bbl | ~7.6–8.2:1 | 4.120" x 3.75" |
| Pontiac 350 V8 (2-bbl) | 90° OHV V8, iron block/heads | 350 cu in (5.7 L) | ~160–170 hp (application dependent) | Naturally aspirated | ~5,000 rpm | Rochester 2-bbl | ~7.6–8.0:1 | 3.875" x 3.75" |
| Pontiac 301 V8 (2-bbl) — 1977 availability | 90° OHV V8, iron block/heads | 301 cu in (4.9 L) | ~135–150 hp (market dependent) | Naturally aspirated | ~5,200 rpm | Rochester 2-bbl | ~7.6–8.0:1 | 4.00" x 3.00" |
Transmissions were overwhelmingly Turbo-Hydramatic automatics: TH400 behind higher-torque engines (notably 455s) and TH350 with 400s and smaller displacements. Manual gearboxes were essentially absent from this generation’s Grand Prix ordering charts.
Driving Experience and Handling Dynamics
In SJ tune, the big Pontiac blends relaxed grand-touring with unexpectedly tidy body control for its size. The long wheelbase and wide track serve highway composure, while Radial Tuned Suspension—firmer springs, heavier anti-roll bars, specific shocks, and radial tires—resist the wallow that plagued softer rivals. Steering is Saginaw recirculating-ball, usually variable-ratio and boosted; it’s light at parking speeds and calm on center, with more feel than the class norm once the chassis loads up.
Throttle response depends on the engine: a well-tuned Quadrajet 455 squirts the car into gaps with a burly midrange; the 400 remains the best all-rounder, smoother and more economical while still authoritative. Emissions-era spark curves and EGR can blunt part-throttle crispness if neglected; properly sorted, these cars deliver a clean, deep beat and dignified urgency. The Turbo-Hydramatic is a fine partner—decisive kickdown and unobtrusive shifts, the TH400 in particular being a benchmark for durability. Braking is front disc/rear drum, with decent pedal feel and ample lining area; the SJ’s tires and suspension calibration make best use of it.
Performance Specifications (Period-typical)
Performance varied meaningfully across years and engine choices. Figures below reflect representative period test results and factory data ranges for 400 and 455-powered cars.
| Metric | Specification |
|---|---|
| 0–60 mph | ~8.7–10.6 seconds (engine/year dependent) |
| Quarter-mile | ~16.0–17.5 sec @ 82–90 mph |
| Top speed | ~115–125 mph |
| Curb weight | ~4,000–4,400 lb |
| Layout | Front-engine, rear-wheel drive |
| Brakes | Front: ventilated discs; Rear: drums (power-assisted) |
| Front suspension | Unequal-length control arms, coil springs, anti-roll bar |
| Rear suspension | Four-link live axle, coil springs; anti-roll bar on SJ/RTS |
| Gearbox | Turbo-Hydramatic 3-speed automatic (TH400/TH350) |
Variants and Trim Structure
Across 1973–1977, the Grand Prix range was organized as follows. The SJ sat as the performance-leaning specification; a luxury-tilted LJ joined mid-cycle.
| Trim/Edition | Years | Positioning and Key Differences | Engines Typically Paired | Production (published) |
|---|---|---|---|---|
| Model J (base) | 1973–1977 | Standard suspension and instrumentation; extensive options; vinyl roof and designer wheel choices common. | 350/400 V8s; later 301 (market dependent) | Not broken out by trim in factory totals |
| SJ | 1973–1977 | Radial Tuned Suspension, fuller gauge package (incl. tach/clock availability), “SJ” exterior badging, GR70-15 radials on Rally II or Snowflake-style wheels (availability by year), heavier anti-roll bars, additional cooling. Traditionally paired with 400/455 four-barrels early; 400 later. | 1973–1976: 400/455 4-bbl; 1977: 400 4-bbl common; lower displacements in some markets | Not broken out by trim in factory totals |
| LJ | 1975–1977 | Luxury-biased: plusher interior trims, wood-tone accents, often Landau half-vinyl roof and wire wheel covers; softer suspension calibrations relative to SJ. | 350/400 V8s; 301 late | Not broken out by trim in factory totals |
Factory literature and GM statistical abstracts enumerate Grand Prix totals by model year but do not consistently publish trim-split volumes. Collectors often verify an SJ via build sheets, cowl tags, and option codes (suspension, wheel/tire, and instrumentation packages).
Model-Year Totals (Grand Prix, Fourth Generation)
Overall production for the fourth-generation Grand Prix was robust. Factory-aligned, widely cited totals by model year are provided below for context.
| Model Year | Grand Prix Total Production | Notes |
|---|---|---|
| 1973 | Approximately mid–150,000s | First Colonnade year; 400/455 engines prominent |
| 1974 | Approximately high–180,000s to low–190,000s | Minor styling and emissions changes |
| 1975 | Approximately low–to–mid 200,000s | LJ introduced; catalytic converters widespread |
| 1976 | Approximately low–to–mid 200,000s | Detail freshening; 455 in final outings |
| 1977 | Approximately high–200,000s | Final year of the generation; 400/301 emphasis |
Note: The figures above reflect commonly referenced totals from period Pontiac/GM sources. For concours-level documentation, consult original invoices, PHS (Pontiac Historic Services) records, or GM Heritage documentation.
Ownership Notes: Maintenance, Parts, and Restoration
- Powertrain: Pontiac V8s are durable with excellent parts support. Keep cooling systems healthy—proper shroud, fan clutch, thermostat, and ignition timing are vital to avoid heat soak that can appear when emissions-era timing is retarded.
- Fuel and ignition: Rochester Quadrajets deliver excellent drivability when rebuilt correctly; throttle shaft bushings and warped air horns are common wear points. Mid-decade cars adopted HEI electronic ignition—ensure full 12V feed, a healthy module, and correct advance curves.
- Transmissions: TH400/TH350 are stout; regular fluid/filter service keeps them nearly indefinite for street use. Kickdown switch and vacuum modulator integrity affect shift behavior.
- Chassis: Radial Tuned Suspension benefits from quality modern bushings and correct-rate shocks. Steering boxes wear; a quality rebuild restores on-center feel. Front end alignments should favor modern radial specs.
- Brakes: Front disc setups are straightforward; ensure caliper slides and proportioning valve are in good order. Performance linings help mitigate the platform’s mass.
- Body and trim: Urethane “Endura” noses and bumper fillers can crack or degrade; reproduction support exists but fitment can require finesse. Vinyl roofs trap moisture—inspect sail panels, opera window channels, and roof seams for rust. Check lower fenders, quarter panels, trunk drop-offs, and rear window channels.
- Electrical/Climate: Vacuum actuators for HVAC and cruise control age out; lines and pods are service parts. The A6 compressor is rebuildable; update to modern refrigerant and hoses if necessary.
- Service intervals (period typical): Engine oil 3,000–5,000 miles with quality detergent oil; transmission fluid/filter ~30,000 miles; differential fluid ~60,000 miles; cooling system every 2 years; pre-HEI ignition points/condensor ~12,000 miles (HEI needs periodic cap/rotor/plugs only).
- Restoration difficulty: Mechanical work is straightforward with broad interchange across GM A-body lines. The challenge lies in sourcing clean body shells and excellent interior/trim pieces specific to Grand Prix—particularly dash bezels, unique SJ badging, and correct wheel/trim combinations.
Cultural Relevance and Collector Insight
The fourth-generation Grand Prix captured the American appetite for tailored luxury with latent muscle. As a symbol of the personal-luxury boom, it was as common at country clubs as it was thundering down turnpikes. On track, while overshadowed by Chevrolet’s NASCAR-focused Laguna and Monte Carlo, Pontiac’s big coupe nonetheless contributed to the era’s silhouette in regional stock car circles.
Collector interest clusters around authentic SJ cars with documented drivetrains—especially 455-equipped examples from the early/mid years and low-mile 400 cars from 1977. Original colors with period-correct wheels (Rally II, and later alloy patterns where offered), intact engine-turned dash fascias, and rust-free roof structures draw premiums. Well-documented SJ 455s in excellent condition have achieved strong five-figure results at major auctions, with investment-grade cars benefitting from provenance and originality rather than bolt-on modifications.
FAQs
What engines did the 1973–1977 Grand Prix SJ use?
Across the cycle, SJ cars most commonly paired with Pontiac’s 400 or 455 four-barrel V8s. The 455 was prevalent through 1976 in many markets; by 1977, the 400 became the primary performance choice as the 301 entered the lineup as an economy option. Exact availability varied by model year and emissions market.
How quick is a Grand Prix SJ?
Period tests of healthy 400/455 cars typically show 0–60 mph in the high-8 to low-10 second range, quarter-mile in the mid-16s to high-17s, and a top speed around 115–125 mph depending on gearing and tune.
Known problem areas?
- Cracking or aging urethane front noses and bumper fillers
- Vinyl roof rust at sail panels and opera window surrounds
- Worn steering boxes and tired suspension bushings affecting road feel
- Carburetor wear (Quadrajet throttle shafts, air horn warpage)
- Vacuum leaks impacting HVAC and cruise control performance
Are parts available?
Mechanical and chassis parts are readily available thanks to broad GM A-body interchange. Trim unique to the Grand Prix—particularly SJ-specific emblems, dash fascias, and certain interior pieces—takes more hunting, but reproduction support and good used parts exist.
What is the difference between SJ and LJ?
Both were upmarket, but the SJ skewed toward driving with RTS, fuller instrumentation, uprated wheels/tires, and typically larger engines. The LJ (added mid-decade) emphasized luxury and appearance with plusher interiors and softer ride calibrations.
What transmission did the SJ use?
Nearly all cars carried Turbo-Hydramatic automatics—TH400 with the largest engines and TH350 with others. Manual transmissions were effectively not offered on this generation of Grand Prix.
Value trends?
Collectors favor authenticity and documentation. Early/mid-decade SJ cars with 455s and late, clean 400-equipped examples carry a premium over base-spec cars. Originality, condition, colors, and paperwork weigh more than aftermarket modifications.
Why the Fourth-Gen SJ Still Matters
Because it distilled Pontiac’s long-held promise—exuberant style with honest GT substance—into a car that could cross states effortlessly and arrive with presence. The SJ isn’t a homologation special; it’s a meticulously tuned personal-luxury coupe that still rewards an enthusiast who values torque, stance, and the confidence of a big chassis made to work.
