ATK HP81C Ford 408 Stroker 480HP Stage 3 Complete Long Block Crate Engine

Description

Command brutal asphalt-shredding Windsor torque through the ATK HP81C Crate Engine in Stage 3 complete street-strip configuration. Pumping out 480 horsepower at 5,500 RPM and 490 lb-ft torque at 4,200 RPM, this 408 cubic inch Ford power plant arrives dressed with carburetor, ignition, and water pump. It furnishes pro-street builds with tire-smoking small-block authority straight from the pallet.

A blueprinted 351 Windsor cast iron block forms the rigid structural foundation, equipped with a leak-resistant 1-piece rear main seal. The internally balanced rotating kit features a 4340 forged steel 4.000-inch stroke crankshaft, 4340 forged H-beam rods, and 10.5:1 forged pistons inside 4.030-inch bores. An internal neutral balance configuration joins an oil-baffled steel pan for total crankcase fluid control.

Key Features of ATK HP81C

Restoration builders choose to buy ATK HP81C crate engine packages to bypass parts sourcing delays and gain dyno-proven Windsor horsepower. This complete package drops straight into classic Ford muscle cars, custom pickups, and aggressive street rods.

• 750 CFM dual-feed four-barrel carburetor discharges calibrated fuel mixtures straight out of the secure shipping crate.
• High-flow dual-plane aluminum intake manifold flows balanced fuel charges into oversized intake runners past 5,500 RPM.
• 205cc aluminum cylinder heads maximize heat dissipation to resist detonation while reducing front-end vehicle weight.
• 0.576-inch lift hydraulic roller camshaft delivers aggressive valve lift curves without requiring constant solid-lifter valve adjustments.
• 230-degree intake duration at 0.050-inch lift profiles the powerband for massive pulling force off launching lines.
• 1.6:1 ratio aluminum roller rockers guide valves without valve stem galling during hard quarter-mile acceleration pulls.
• ATK HP81C complete power packages include a high-output electronic distributor and spark plug wires for hot spark delivery.
• High-flow cast iron water pump circulates coolant through internal passages to shed excess block operating heat.

Dyno Profile Combustion Performance

Dyno testing validates 480 brake horsepower at 5,500 RPM backed by 490 lb-ft torque at 4,200 RPM across a 2,500 to 6,000 RPM band. High compression demands 93-octane premium service-station gasoline. Manifold vacuum settles at 12 in-Hg at an 850 RPM idle setting. Internal oil pump pressure regulates firmly between 45 and 65 PSI under load.

Chassis Clearances Bellhousing Integration

External block dimensions match standard 351 Windsor profiles, seating between frame rails in vintage Mustangs, Torinos, and Ford trucks. The internally balanced crank tail accepts standard zero-balance flexplates or flywheels for C6 or manual gearboxes. Engine mount locations fit factory Ford frame pads, leaving space for tubular exhaust headers and steering linkages.

Start Protocols Operation Boundaries

Pre-lube the engine with a dedicated mechanical tool before turning the ignition key to ensure complete bearing lubrication. Fill the crankcase with 10W-30 conventional break-in lubricant loaded with zinc and phosphorus additives. This turn-key engine is not designed for salt water marine use, supercharged boost past 7 PSI, or bracket-racing nitrous systems.

• Drain break-in motor oil and spin on a new filter canister after the first 500 operating miles.
• Inspect carburetor throttle linkage, fuel line fittings, and baseplate bolts every 3,000 miles of street use.
• Check ignition distributor advance weights, rotor contacts, and spark wires every 12 months or 12,000 miles.

Warranty Information Package Inventory

ATK protects this package with a 12-Month factory warranty against defects in materials and manufacturing. The wooden shipping container holds the fully dressed engine, carburetor, intake manifold, distributor, spark plug wires, water pump, harmonic balancer, flexplate, oil pan, valve covers, and official dynamometer test sheet.