About the Pontiac 455 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. Displacement is achieved internally through bore and stroke changes. 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 in those years, 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 causing pressure loss. 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

The 455 was produced in several distinct versions. Verified output figures sourced from authoritative Pontiac reference data:

Common Casting Numbers and Part Numbers , Reference

We document the casting number and date code of every unit. Available on request before you place your order.

What Is Included , What Is Not Included

Vehicle Compatibility , Direct Fit

The following vehicles left the factory with the Pontiac 455 V8 as a direct fit:

Swap compatibility: All Pontiac V8 engines from the 326 through the 455 share identical external block dimensions and motor mount locations. The 455 bolts into any 1967-and-newer Pontiac originally equipped with any Pontiac V8 , including earlier GTOs, Firebirds, and full-size models. Correct intake, carburetor, and exhaust are required depending on head type.

Transmission compatibility: Turbo-Hydramatic 400 (TH400) , most common and strongest pairing | TH350 , lower-output applications | Muncie 4-speed manual (M20, M21, M22) , performance applications.

Not sure if this fits? Call (240) 301-0095 with your year, make, model, and current drivetrain. We verify fitment before every order ships.

Common Names and Search Terms

Used OEM vs Rebuilt vs Aftermarket , 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

Mileage varies by unit. Where available from the donor vehicle we provide it. Where mileage cannot be confirmed, we disclose this before your order is placed. Full inspection documentation available on request.

Buyer Tips , What to Know Before You Order

• Know your variant: HO (round-port heads 1971 to 1973), Super Duty (1973 to 1974, rarest), and base units (D-port 1970, detuned 1973 to 1976) have different characteristics and values. 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 from a 1970 base engine will not fit on an HO block without a head change. Tell us which head type your car currently has.
• 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 for your build.
• Transmission: TH400 is the strongest automatic pairing. Muncie 4-speeds bolt directly. TH350 works in lower-output applications.
• Crankshaft interchangeability: Pontiac 455 cranks are interchangeable with the 400, enabling stroker builds. Tell us if you are buying this as a stroker core.

Why Buy ****From**** Vaz Auto Solutions

• Variant confirmed before you pay , HO, SD, or base documented including head type and main cap configuration
• Casting number and date code on record for every unit
• Compression tested across all 8 cylinders , results shared before order is confirmed
• Fitment verified for your specific Pontiac vehicle before every order ships
• No core charge , keep your old engine
• Free freight pallet delivery to all 50 states, no hidden fees
• 15 day replacement warranty on internal engine defects
• Call (240) 301-0095 , someone who understands 455 variants, casting differences, and Pontiac restoration

**ZONE 5: ADDITIONAL INFORMATION**

**ZONE 6: WARRANTY**

15 Day Replacement Warranty

Every used Pontiac 455 engine sold by Vaz Auto Solutions is covered by a 15 day replacement warranty from the date of delivery.

Covered:

• Internal defects present at the time of delivery
• Part does not perform as described
• Wrong part shipped due to our fulfilment error

Not covered:

• Damage from improper installation
• Damage from incompatible components
• External components unless specifically listed
• Labor costs of any kind

To make a claim, contact us within 15 days of delivery at (240) 301-0095 or info@vazautosolutions.com.

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