ATK GM 383 Stroker 375 HP HP33 Stage 1 Long Block
Heavy street machines rely on the ATK GM 383 375HP for massive low end grunt. Built on a cast iron block with 9.5:1 compression. Source your own induction setup. Drive hard.
- Stroked 6.3L rotating assembly generates raw torque
- Nine point five compression burns pump gas
- One piece seal prevents annoying garage drips
Description
The massive 383 stroked internal displacement of the ATK GM 383 Stroker 375 HP HP33 Stage 1 Long Block addresses restrictive factory cylinder pressure limits. Experience aggresive off-the-line torque during classic car cruising and towing. This build utilizes heavy-duty cast iron heads to output three hundred seventy-five horsepower smoothly.
Key Features of ATK GM 383 Stroker 375 HP HP33
- GM 4-Bolt Main Cast Iron Block: Features seasoned main bearing caps clamped with high-tensile fasteners to eliminate block flexing under load.
- Heavy-Duty Cast Iron Cylinder Heads (76cc Chambers): Offers robust structural reliability and increased thermal retention for dependable street performance.
- Scat Nodular Iron Stroker Crankshaft: Extends the piston stroke to 3.750 inches to generate massive low-end and mid-range torque.
- GM Powder Metal Connecting Rods: Absorbs severe combustion pressures safely to ensure long-term mechanical reliability.
- Hydraulic Roller Camshaft (.442″/.465″ Lift): Reduces internal valvetrain wear while producing a smooth daily-driven idle and flat power band.
Component Breakdown: Base Long Block Configuration
This assembled base long block provides a formidable small block foundation for high performance engine swaps and direct repowers.
- A precision machined cast iron block houses a robust hydraulic roller camshaft designed to deliver a massive torque curve for heavy street applications.
- Heavy duty cast iron cylinder heads improve overall thermal efficiency while thick internal bearings maintain steady oil pressure under load.
Vehicle Fitment & Compatibility Matrix
Engineered to drop seamlessly into classic Chevrolet engine bays this 5.7L block aligns perfectly with standard motor mounts. Sourcing one of our high-output Chevy small block engines modernizes the powertrain of your classic vehicle instantly.
- Fits 1967-1981 Chevrolet Camaro models looking for an authentic 383 power upgrade.
- Fits 1973-1987 Chevrolet C10 pickup trucks requiring a heavy duty replacement block.
- Fits 1964-1972 Chevrolet Chevelle platforms needing robust low end towing torque.
- Fits 1968-1974 Chevrolet Nova applications seeking a direct fit replacement.
Fuel & Ignition System Requirements (Tech Notes)
Feeding this classic small block engine demands proper fuel tuning and reliable ignition components.
- An upgraded mechanical or electronic fuel pump is required to supply your carburetor while utilizing 91 Octane premium pump gas prevents pre-ignition.
- Heavy duty spark plug wires must be utilized alongside an HEI distributor to maintain a powerful spark across the RPM band.
Installation, Break-In Oil & Priming Instructions (Tech Notes)
Proper initial startup procedures ensure the longevity of the hydraulic roller lifters and internal bearings.
- Transfer your existing intake manifold using fresh gaskets before manually priming the oil system with a dedicated priming tool until pressure is verified.
- Fill the crankcase with a high zinc break in oil and perform a varied RPM heat cycle before driving conservatively for the first 500 miles.
USA Warranty, Emissions & Logistics
Investing in this ATK High Performance crate engine secures peace of mind through comprehensive manufacturer backing.
- Backed by a strict 1-Year manufacturer warranty this engine provides excellent protection against internal manufacturing defects when installed properly.
- This assembly is not legal for sale or use on pollution controlled motor vehicles in California and ships securely via LTL freight.
ATK High Performance HP33 GM 383 Stroker 375 HP Stage 1 LB Specs
| Brand | ATK High Performance Engines |
| Engine Model | HP33 |
| Part Type | Crate Engines |
| Product Line | ATK High Performance GM 383 Stroker 375 HP Stage 1 Long Block Crate Engines |
| Engine Type | HPE-HP33 |
| UPC | 00653517143441 |
| Crate Engine Family | Chevy Small Block |
| Actual Engine Displacement | 6.3L / 383 |
| Crate Engine Cylinder Head Material | Cast iron |
| Engine Block Material | Cast iron |
| Advertised Compression Ratio | 9.5:1 |
| Assembled | Yes |
| Engine Balance | Internal/External |
| Cam Style | Hydraulic roller, OE roller |
| Rear Main Seal Style | 1-piece |
| Intake Manifold Included | No |
| Cylinder Heads Included | Yes |
| Carburetor Included | No |
| Throttle Body Included | No |
| Distributor Included | No |
| Oil Pan Included | Yes |
| Valve Covers Included | Yes |
| Timing Cover Included | Yes |
| Water Pump Included | No |
| Harmonic Balancer Included | No |
| Flexplate Included | No |
| Flywheel Included | No |
| Air Cleaner Included | No |
| Spark Plugs Included | No |
| Spark Plug Wires Included | No |
| Computer Included | No |
| Wiring Harness Included | No |
| Supercharger Included | No |
| Warranty Info | 1 Year |









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