ATK Marine VMB3 Chevy 305 5.0L Rebuilt Long Block Engine
Cabin cruisers regain reliable lake performance with the ATK Marine VMB3 305 long block swap. This budget friendly 5.0L iron block runs flat tappet lifters and has a pre-installed pan. Bolt on your manifold. Cruise local channels.
- Small block design fits tight bilge engine boxes
- Included oil pan simplifies drop-in installation process
- Flat tappet cam runs smooth on cheap fuel
- Cast iron cylinder heads match stock cooling patterns
- One piece main seal provides a dry seal
Description
Economical marine repower projects require the ATK Marine VMB3 Chevy 305 5.0L Rebuilt Long Block Engine and its reliable factory displacement. Maintain steady hull planing speeds during weekend recreational boating. This build utilizes a seasoned 5.0L iron block to deliver reliable marine propulsion safely.
Key Features of ATK Marine VMB3 Chevy 305 5.0L
- Seasoned 5.0L Cast Iron Marine Block: Provides exceptional structural rigidity to support continuous high-load operation in marine environments.
- One-Piece Rear Main Seal: Upgrades the engine block sealing capabilities to prevent oil leaks into the boat bilge area.
- Cast Iron Cylinder Heads: Resists thermal stress and extreme operating temperatures under sustained high-load marine operation.
- Marine-Calibrated Flat Tappet Camshaft: Engineered specifically to deliver a broad and predictable marine torque curve for steady water displacement.
- 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 late-model classic marine engines this 5.0L block aligns perfectly with standard marine motor mounts. Sourcing one of our reliable GM marine replacement blocks restores the propulsion of your vessel instantly.
- Fits inboard marine propulsion systems utilizing standard-rotation Chevrolet small block architecture.
- Fits stern-drive marine propulsion systems requiring a 5.0L engine replacement.
- Fits vintage runabouts and sport fishing boats looking for an authentic 5.0L 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.
ATK High Performance HP19 Ford 460 525 HP Stage 1 Long Block Specs
| Brand | ATK Marine Engine |
| Engine Model | VMB3 |
| Part Type | Crate Engines |
| Product Line | ATK Marine Rebuilt Long Block Engines |
| Engine Type | HME-VMB3 |
| UPC | 00653517287381 |
| Crate Engine Family | Chevy Small Block |
| Engine Displacement | 5.0L / 305 |
| Cylinder Head Material | Cast Iron |
| Engine Block Material | Cast Iron |
| Assembled | Yes |
| Engine Balance | Internal/External |
| Cam Style | Hydraulic flat tappet |
| 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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