ATK Marine DM20 Chevy 350 5.7L Rebuilt Long Block Engine

Description

Demanding open-water navigation requires the ATK Marine DM20 Chevy 350 5.7L Rebuilt Long Block Engine and its robust cast iron architecture. Achieve consistent cruising speeds during heavy recreational boating applications. This build utilizes a seasoned 5.7L cast iron block to deliver reliable marine propulsion safely.

Key Features of ATK Marine DM20 Chevy 350 5.7L

• Seasoned 350 CID Cast Iron Marine Block: Establishes a highly rigid foundation to prevent structural flexing under constant hull resistance.
• Marine-Calibrated Hydraulic Flat Tappet Camshaft: Optimizes valve timing events to produce a flat torque curve and reliable low-speed docking idle.
• Cast Iron Cylinder Heads: Dissipates extreme combustion temperatures safely during sustained high-load marine cruising.
• Two-Piece Rear Main Seal: Ensures direct compatibility with classic marine transmissions and pre-1986 stern-drive hardware.
• Internally Balanced Rotating Assembly: Minimizes harmonic vibrations to protect the crankshaft main bearings from premature wear during extended cruising.

Component Breakdown: Marine Rebuilt Long Block

This assembled marine base long block provides a formidable foundation for classic boat repowers and complete propulsion overhauls.

• A precision machined cast iron block houses a marine calibrated camshaft designed to deliver consistent low-end torque.
• Heavy duty cast iron cylinder heads improve overall thermal retention while thick internal bearings maintain steady oil pressure under constant load.

Vehicle Fitment & Compatibility Matrix

Engineered to replace classic marine engines this 5.7L block aligns perfectly with standard marine motor mounts. Sourcing one of our heavy-duty Chevy marine engines restores the propulsion of your vessel instantly.

• Fits classic inboard marine propulsion systems utilizing standard-rotation Chevrolet small block architecture.
• Fits classic stern-drive marine propulsion systems requiring a 350 CID engine replacement.
• Fits vintage runabouts and sport fishing boats looking for an authentic 5.7L marine power upgrade.

Fuel & Ignition System Requirements

Feeding this classic marine engine demands proper fuel tuning and reliable USCG-approved ignition components.

• A USCG-approved mechanical marine fuel pump is required to supply your carburetor while utilizing marine-grade fuel prevents pre-ignition.
• Heavy duty spark plug wires must be utilized alongside an approved marine distributor to maintain a powerful spark and prevent bilge explosions.

Installation, Break-In Oil & Priming Instructions

Proper initial startup procedures are absolutely critical to ensure the survival of the hydraulic flat tappet camshaft and lifters.

• Transfer your existing marine 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 hold the engine steady at 2000 RPM for 20 minutes to properly seat the flat tappet lifters.

USA Warranty, Emissions & Logistics

Investing in this ATK Marine rebuilt 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 in a marine application.
• This assembly requires a valid core exchange of your original marine block and ships securely via LTL freight to commercial addresses.