Pontiac 455 Engine for Sale | Used OEM 455ci V8 (7.5L)

About This Engine

The Pontiac 455 is the largest displacement production V8 Pontiac ever built. Introduced for the 1970 model year by expanding the bore of the 428 to 4.155 inches and extending the stroke to 4.21 inches, it displaced an actual 457.6 cubic inches and delivered one of the most torque-heavy power curves of the entire muscle car era. At its peak, the 455 HO produced 370 hp and 500 lb-ft of torque – figures that put it among the most powerful street engines available anywhere at the time.

One characteristic that sets the Pontiac 455 apart: all Pontiac V8 engines from the 326 through the 455 share identical external block dimensions and motor mount locations. This means the 455 physically bolts into any vehicle originally using any Pontiac V8, making swaps and replacements straightforward with the correct supporting components.

The 455 powered the GTO, Firebird, Trans Am, Grand Prix, LeMans, Catalina, Bonneville, and Grand Ville through 1976. Today, a documented used OEM unit with known casting numbers and a confirmed variant is the foundation every serious Pontiac restoration builds on.

Signs You Need a Replacement Engine

• Knock or rattle under load – rod or main bearing wear on high-mileage units
• Blue smoke on startup or under acceleration – worn valve seals or piston rings
• Loss of compression on one or more cylinders – scored walls, worn rings, or head gasket failure
• Low oil pressure at idle on a warmed-up engine – main bearing clearance out of tolerance
• Coolant in the oil or white exhaust smoke – head gasket failure, common on late-emission blocks run hot
• Rough idle that worsens as the engine warms – worn cam lobes, a known high-mileage Pontiac V8 issue
• Excessive oil consumption beyond 1 quart per 1,500 miles – valve stem seal or ring failure

Known Problems With This Engine

• Late-emissions output drop: The 1975 and 1976 455s produced as little as 200 hp at 7.6:1 compression. Fine for a stock replacement, not suitable as a performance build core. We document the year and variant before shipping.
• 2-bolt main caps from 1973 onward on base blocks: After 1972, standard 455 blocks switched from 4-bolt to 2-bolt main caps. Super Duty units retained 4-bolt. If your build requires 4-bolt, specify during the quote process.
• Round-port vs D-port head intake incompatibility: 1970 base 455s used D-port cylinder heads. 1971 onward HO engines used round-port heads requiring a different intake manifold. We document the head casting before every order ships.
• Oil pump drive wear: High-mileage Pontiac V8s can develop wear in the oil pump driveshaft area. We inspect and record oil pressure on every unit.
• Rear main seal seepage: Two-piece rear main seals on these engines seep on aged units. We inspect all gasket surfaces and disclose any seepage before shipping.

Known Variants by Year and Output

Common Casting Numbers

What Is Included / What Is Not Included

INCLUDED (Long Block): Block, crankshaft, pistons, connecting rods, camshaft, cylinder heads, valve train, oil pan, timing cover, and water pump where present.

NOT INCLUDED: Intake manifold, carburetor, exhaust manifolds, distributor, ignition system, alternator, power steering pump, A/C compressor, starter, flexplate or flywheel, accessory brackets.

No Core Charge: You are not required to return your old engine.

Vehicle Compatibility – Direct Fit

Swap compatibility: The 455 bolts into any 1967-and-newer Pontiac originally equipped with any Pontiac V8. Transmission compatibility: TH400 (strongest) | TH350 | Muncie 4-speed M20/M21/M22.

Common Names and Search Terms

Pontiac 455 | 455 Pontiac engine | Pontiac 455 motor | 455 HO engine for sale | 455 Super Duty for sale | Pontiac GTO engine for sale | Pontiac Trans Am 455 engine | Pontiac Firebird 455 | 455 Pontiac big block | Pontiac 7.5L engine

Used OEM vs Rebuilt – Which Is Right for You

Used OEM is the right choice for a GTO, Trans Am, or Firebird restoration – particularly where period-correct condition matters. Our 455s are compression tested with casting numbers and variant documented. A professionally rebuilt unit makes sense for a show car or specific tolerance build. Rebuilt HO and SD units typically run $5,000 to $9,000 or more from specialists. Call us to discuss sourcing options.

Condition and Inspection Process

• Compression test across all 8 cylinders – pressure per cylinder recorded
• Visual inspection of block for cracks, deck damage, scored journals, stripped threads
• Leak check on all gasket surfaces for active oil or coolant seepage
• Valve cover inspection for sludge and cam wear indicators
• Casting number, date code, and variant confirmed – D-port or round-port head noted
• Main cap configuration confirmed – 2-bolt or 4-bolt noted before shipping

Buyer Tips – What to Know Before You Order

• Know your variant: HO (round-port heads 1971-1973), Super Duty (1973-1974, rarest), and base units have different characteristics. Specify when calling.
• Round-port vs D-port intake: If your vehicle has an HO engine, the intake manifold is round-port specific. A D-port intake will not fit on an HO block without a head change.
• 4-bolt vs 2-bolt mains: All pre-1973 standard 455s and all Super Duty units have 4-bolt mains. Post-1972 base engines use 2-bolt. Specify if 4-bolt is required.
• Crankshaft interchangeability: Pontiac 455 cranks are interchangeable with the 400, enabling stroker builds.

FAQs

What vehicles does the Pontiac 455 fit