ATK HP33 GM 383 Stroker 375 HP Stage 1 Long Block Crate Engine

Description

Cast iron cylinder heads reinforce the ATK HP33 GM Crate Engine 383 Stroker Stage 1 package. Engineered for classic Camaros, Chevelles, and square-body GM trucks, this 6.3-liter small-block Chevrolet V8 produces 375 brake horsepower at 5,200 RPM. Stroker displacement combined with a hydraulic roller camshaft produces colossal low-RPM pulling torque while retaining dependable pump-gas street manners.

Engine builders hand-select seasoned GM cast iron four-bolt main blocks, align-honing main journals and squaring block decks flat. A nodular iron stroker crankshaft spins with internal-external balance weighting inside a one-piece rear main seal casing. Forged steel connecting rods attach to 4.030-inch hypereutectic pistons across a 3.750-inch stroke. A 9.5:1 compression ratio pairs with cast iron cylinder heads. Oil capacity holds 5.0 quarts. Dry long block weight totals 435 lbs.

Key Features of ATK HP33

Truck owners and street machine builders buy ATK HP33 crate engine base long blocks to obtain massive 383 stroker torque while utilizing their preferred intake manifold and accessories. The long block drops flush into vintage GM engine compartments using stock motor perches.

• 3.750-inch stroker crankshaft expands displacement to 383 cubic inches for massive low-end torque.
• Cast iron cylinder heads feature hardened exhaust seats to endure modern unleaded pump fuels.
• Hydraulic roller camshaft profiles produce smooth valve lift with reduced valvetrain friction.
• Four-bolt iron main caps secure the crank train against bottom-end journal flex.
• Hypereutectic aluminum pistons maintain close bore clearances under heavy vehicle acceleration.
• One-piece rear main seal structure prevents oil weeping past the flywheel flange.
• Stamped steel oil pan maintains continuous oil pickup submersion during sudden acceleration.
• Balanced ATK HP33 rotating components cancel secondary harmonics under sustained vehicle load.

Dynamic 383 Stroker Dyno Output

Operating across an authoritative 1,800 to 5,400 RPM power band, this 383 stroker long block produces 375 brake horsepower and 440 lb-ft torque on 87-octane or 89-octane pump gasoline. The performance hydraulic roller camshaft specifies 218 degrees intake duration at 0.050-inch lift with 0.495-inch valve lift. Manifold vacuum measures 16 in-Hg at a 750 RPM curb idle. Hot oil pressure holds between 40 to 60 PSI, keeping crank journals and overhead valvetrain hardware lubricated with pressurized oil during continuous vehicle acceleration.

Engine Bay Subframe Fitment Clearances

This small block Chevrolet engine utilizes standard GM 90-degree V8 transmission bellhousing patterns, bolting straight to TH350, TH400, 700R4, and manual transmissions. Internal-external balanced rotating groups require matching flexplates or flywheels. Motor mount pads align with factory GM chassis crossmembers. The rear-sump passenger-car oil pan clears front suspension steering linkages and crossmembers without modification.

Break-In Protocol Maintenance Duty Limits

Pre-lube engine oil passages with high-zinc 10W-30 mineral oil using a mechanical primer before initial starter cranking. Fill and bleed coolant through the thermostat housing to eliminate trapped air pockets. This engine package is not engineered for supercharger boost exceeding 6 PSI, continuous RPM past 5,800, or raw marine sea water cooling.

• Drain break-in motor oil after the first 50 road miles.
• Renew synthetic or conventional motor oil every 3,000 miles.
• Inspect ignition timing, spark plugs, and valve adjustment every 12 months.

Warranty Coverage Pallet Crate Manifest

A 12-Month limited warranty protects against material and manufacturing defects. The banded wooden pallet crate houses the base long block, cast iron cylinder heads, stamped steel oil pan, valve covers, timing cover, dyno verification printout, and installation guide. Components ship sealed in protective plastic wrap against oxidation.