The Premium Marine Crate Engine for Chevrolet Inboard Applications

The ATK DMW4 marine crate engine is a premium-quality rebuilt long block specifically engineered for marine applications. Based on the Chevrolet 4.3L/262 cubic inch V6, this marine engine is designed to deliver maximum performance and long-term durability for your boat . Whether you’re repowering a stern drive, inboard, or jet boat, this ATK Marine engine provides the reliability and power that boaters demand.

What Makes the ATK DMW4 a Marine-Specific Powerplant?

The DMW4 is far more than a standard automotive engine—it’s a purpose-built marine engine with specialized components that address the unique demands of boating. ATK Marine Engines uses special marine pistons and rings, a special marine camshaft, and marine-specific gaskets to ensure longevity in harsh marine environments . Each engine is tested (with most being hot-run tested) for compression, oil pressure, oil leaks, engine noise, and general operating conditions before shipment .

4.3L V6 Marine Engine Specifications

What’s Included with Your ATK DMW4 Marine Long Block

The DMW4 comes as an assembled long block with the following components included :

Important Note: The following components are NOT included and must be transferred from your existing engine or sourced separately: intake manifold, carburetor/throttle body, distributor, oil pan, valve covers, timing cover, water pump, harmonic balancer, and flexplate/flywheel .

Marine-Specific Features and Engineering

Reverse-Engineered for Quality

ATK Marine engines are built with a reverse-engineering philosophy to discover original factory deficiencies and, where possible, make improvements . This approach ensures that the remanufactured engine often outperforms the original in durability and reliability.

Rigorous Testing and Quality Control

Each ATK Marine engine undergoes comprehensive quality testing :

• Magnafluxing of engine blocks to detect cracks

• Precision honing of cylinders with mains being line-honed

• Precision surfacing of engine blocks and cylinder heads

• Three-angle valve seat machining on cylinder heads

• Stress-relieving, precision grinding, and micro-polishing of crankshafts

Marine-Specific Components

The DMW4 features several marine-specific upgrades :

• Marine pistons and rings designed for sustained high-RPM operation

• Marine camshaft optimized for marine torque curves

• Marine gaskets resistant to corrosion in marine environments

• Heavy-duty double roller timing chain for durability

• Quality OE-level components rather than generic “white box” parts 

DMW4 Marine Engine Applications

Compatible Marine Applications

The ATK DMW4 is a direct-fit replacement for Chevrolet 4.3L V6 marine applications, including:

• Stern drive boats

• Inboard boats

• Jet boat applications

• Replacement for 4.3L/262 V6 marine engines 

Fitment Notes

According to product specifications :

• Standard rotation (clockwise)

• Block Casting: 090M

• Head Casting: 113

• With balance shaft (last 3 digits 542 or 748)

• Roller cam with roller rockers

• Metric bolts for starter

• Motor mounts and bell housing compatible

Emissions Compliance

Important: The ATK DMW4 engine is NOT legal for installation on vehicles required to meet CARB standards and/or registered in California and other states following CARB standards, including NY and ME .

Break-In and Installation Recommendations

Break-In Procedure

ATK Marine engines require proper break-in:

• Use break-in oil or conventional (non-synthetic) oil with zinc additive for the first 500 miles

• Vary engine speed during break-in

• Monitor oil pressure and coolant temperature closely

• Change oil and filter after break-in period

Installation Notes

• All external accessories must be transferred from your original engine

• Engine includes oil pump and gasket 

• Verify rotation direction (standard rotation) for your marine application

• Consult marine-specific installation guidelines for proper alignment

ATK DMW4 Marine Engine FAQs

What is the horsepower of the ATK DMW4?

The DMW4 marine engine produces between 175-230 horsepower depending on induction and tuning .

What is the displacement of the DMW4?

The DMW4 has a displacement of 4.3L / 262 cubic inches .

What’s included with the ATK DMW4 marine long block?

The DMW4 includes the assembled long block with cylinder heads, marine pistons, rings, camshaft, gaskets, valves, bearings, lifters, heavy-duty timing chain, and freeze plugs. Intake manifold, carburetor, distributor, oil pan, valve covers, timing cover, water pump, and harmonic balancer are not included .

Is the DMW4 a standard rotation or reverse rotation engine?

The DMW4 is a standard rotation (clockwise) marine engine .

What is the warranty on the ATK DMW4 marine engine?

The DMW4 is backed by a comprehensive warranty. See product documentation for full warranty details .

Is the DMW4 emissions legal?

No. This engine is NOT legal for installation on vehicles required to meet CARB standards .

Why Choose NH Race Engine for Your Marine Crate Engine?

As a Netherlands-based specialist serving performance enthusiasts across Europe, NH Race Engine brings unmatched expertise to your marine project. We understand the unique requirements of marine applications—from corrosion resistance to proper cooling. Browse our Marine Engines collection and other crate engine offerings to find the perfect solution for your build.

Order Your ATK DMW4 Marine Crate Engine from NH Race Engine Today

The ATK DMW4 marine crate engine delivers exceptional value for boat repower projects. With ATK’s industry-leading remanufacturing process, comprehensive warranty, and NH Race Engine’s European distribution network, you can trust that your replacement marine engine delivers the quality and reliability you demand.

Contact NH Race Engine today to discuss your DMW4 engine requirements. Our expert team can help you navigate compatibility, shipping, and installation considerations for your European marine application.