ATK HP89CBLK GM 350 390HP Stage 3 Crate Engine | Ultimate Product Guide

The ATK HP89CBLK is a high-performance, 390 horsepower Stage 3 crate engine that delivers turn-key power for street rods, muscle cars, and trucks. Based on the legendary Chevrolet 350 small block platform, this engine combines a remanufactured cast iron block with performance aluminum cylinder heads and a hydraulic roller camshaft for a potent mix of reliable street manners and aggressive power.

This is a complete long block package, arriving with virtually everything needed to run: a carburetor, intake manifold, distributor, plug wires, and all front accessories. Each engine is hand-assembled and balanced to ensure smooth operation and maximize the output of its 10.0:1 compression hypereutectic pistons. With 420 lb-ft of torque, the ATK Stage 3 350 is built to deliver thrilling performance right out of the crate.

Detailed Technical Specifications

What’s Included in the Crate:

• Complete Long Block: Assembled short block with installed heads.

• Induction: Intake Manifold & 600+ CFM Carburetor

• Ignition: Distributor, Spark Plug Wires, & Spark Plugs

• Front Accessories: Water Pump, Harmonic Balancer, Timing Cover

• Oil System: Oil Pan, Pump, & Pickup Tube

• Covers: Black Valve Covers & Air Cleaner Assembly

• Gaskets & Seals: Full gasket set installed.

What’s Not Included:

• Flexplate/Flywheel (Required for installation)

• Engine Wiring Harness

• ECU (Not needed – this is a carbureted engine)

ATK Stage 3 vs. OEM & Other Crate Engines: Comparison Table

This table shows where this performance-oriented crate engine fits in the market.

Frequently Asked Questions (FAQ)

Q1: Is this engine new or remanufactured?
A: This engine features a handpicked, remanufactured cast iron block. The block is sourced from original GM engines, professionally cleaned, machined, and fitted with all new performance components. This process ensures strength and reliability while offering excellent value.

Q2: What fuel and octane does this engine require?
A: With a 10.0:1 compression ratio, this engine is designed to run optimally on premium 91-93 octane gasoline. Using lower octane fuel may cause spark knock (pinging) and require timing to be retarded, resulting in lost power and potential engine damage.

Q3: What is the benefit of a hydraulic roller camshaft?
A: A hydraulic roller cam offers several advantages over a flat tappet cam:

• More Power: Allows for more aggressive lobe profiles.

• Improved Reliability: Eliminates the risk of wiping a flat tappet lobe.

• Reduced Friction: Increases horsepower and efficiency.

• Ease of Break-in: No special break-in procedure is required beyond initial cam break-in.

Q4: Does it come with a warranty?
A: Most ATK engines come with a limited warranty (e.g., 3 years/50,000 miles). Always confirm the specific warranty terms with the retailer or ATK directly before purchase.

Q5: What vehicle will this engine fit?
A: This GM 350 small block will fit a vast range of Chevrolet and GMC vehicles from the 1950s through the 1990s (Camaros, Chevelles, Trucks, El Caminos, etc.), as well as many other cars designed to accept a small block Chevy. Note: The included rear sump oil pan may not fit Chevelles with steering behind the crossmember or some Corvettes.

Q6: Is this engine emissions-legal?
A: No. This is a high-performance, non-emissions-legal engine. It is designed for off-road and racing use or for pre-emissions vehicles. It is not certified for use in modern vehicles where emissions testing is required.

Pros and Cons

Pros:

• Turn-Key Package: Includes carb, intake, distributor, and all accessories for a much easier swap.

• Strong Power Output: 390 HP and 420 lb-ft provide serious performance for street or strip.

• Modern Roller Cam Technology: Offers better performance, reliability, and easier break-in.

• Aluminum Heads: Reduce weight and improve heat dissipation over cast iron.

• Excellent Value: Provides a lot of horsepower and included components for the price.

• Hand-Assembled & Balanced: Ensures quality and smooth operation.

Cons:

• Premium Fuel Required: The 10.0:1 compression ratio mandates 91+ octane fuel.

• Not Emissions Legal: For off-road or pre-emissions vehicles only.

• Oil Pan Limitations: The included rear sump pan may not fit all applications, requiring an additional purchase.

• Remanufactured Block: Some builders prefer a brand new block, though remanufactured blocks are perfectly reliable.

• Flexplate/Flywheel Not Included: You must purchase the correct one for your transmission.

Conclusion & Best Applications

The ATK HP89CBLK Stage 3 350 is an outstanding value for anyone looking to add serious horsepower to their project without the hassle of piecing together components. It’s a complete, well-matched package designed for strong, reliable performance.

You should choose this engine if:

• You are building a street rod, classic muscle car, or hot rod truck.

• You want a complete, carbureted engine package that minimizes sourcing parts.

• Your goal is a strong 400 horsepower for aggressive street performance.

• You value the reliability and power of a modern hydraulic roller cam.

• Your vehicle is exempt from emissions testing.

For a powerful, ready-to-run small block Chevy that delivers on its promises, the ATK Stage 3 crate engine is a compelling and popular choice.

Disclaimer: This is a high-performance engine designed for off-road use. Installation should be performed by experienced mechanics. Proper break-in procedures as outlined in the manufacturer’s instructions must be followed. Always ensure the engine is compatible with your vehicle’s chassis and transmission. Fuel system, cooling system, and exhaust must be appropriately sized to handle the increased power output.