for Inboards

A range of perfect engines to replace a classic inboard

383 MAG Inboard 4V

Call 1-800-562-2742 or click here for more information and to order

383 MAG Inboard 4V

340 Crankshaft Horsepower

There is finally the perfect engine to replace a 5.7L or 7.4L classic inboard. This engine delivers more torque than any standard 7.4L big block, and it does so while weighing 150 pounds less. Standard and opposite rotation versions are available, so you don't have to re-engineer your classic boat with a different type of transmission to make it go again.

  • Full roller valvetrain reduces friction and saves on fuel
  • 1-Year Factory Backed Limited Warranty
  • Up to 2-Years of Mercury Product Protection Coverage available

$8999 (Left Hand Rotation) +freight
$11299 (Right Hand Rotation) +freight

  • Standard (LH) Rotation - Transmission not included
    Opposite (RH) Rotation - Transmission not included
HP / kW @ flywheel
  • 340 / 254
Maximum RPM (WOT)
  • 4600 - 5000
Engine type
  • Remanufactured GM V8 Marine Iron Block & Gen+ Heads - 062 Casting
Displacement (CID/L)
  • 383 / 6.3
Bore and stroke
  • 4.03 x 3.75" / 102 x 95 mm
Compression ratio
  • 9.0:1 with Hypereutectic Pistons
Fuel ethanol tolerance
  • Up to 10%
Fuel requirement
  • 87 octane (R+M)/2
Engine control system
  • Thunderbolt V w/Knock Control - MIE Calibration
Fuel delivery system
  • 4V carburetor and mechanical fuel pump
Fuel injection system / carburetor type
  • 750 cfm Weber 4V with electric choke
Air induction
  • Dual Plane Aluminum Intake Manifold with Bronze Inserts
Alternator amp / Watt
  • 65 amp / 917 watt
Water drain system
  • Multi-point drain - Hand Removable Blue Drain Plugs
Exhaust system
  • Iron manifold with Dry-Joint Exhaust Elbow
Cooling system
  • Thermostatically Controlled Raw Water - 143F
Accessory drive system
  • Serpentine belt
Lubrication system
  • High Flow 100 psi Oil Pump and Copper Oil Cooler
Recommended oil
  • SAE 25W-50 FC-W synthetic blend racing oil
Rocker arms
  • 1.6:1 Full Roller Aluminum
Dimensions (L x W x H)
  • 43 x 29 x 22" / 1092 x 737 x 559 mm
Weight (engine only)
  • 980 lbs / 444 kg - When Installed with 72C Transmission

$9499 Now $8999 (Left Hand Rotation) +freight
$10499 (Right Hand Rotation) +freight
Price is plus shipping
Engines cannot be paid for by Credit Card or by PayPal.
One tough marine engine.

Much tougher. And much better. They have to be after what the boater puts them through. It starts at the Mercury factory. It's the only place they remanufacture engines. Back where they were first designed and built. First thing they do is full dis-assembly. The head is completely taken apart and goes through a four-step, high-pressure "hot" cleaning process. Then they inspect everything. They machine, bore, and hone critical components to original tolerances. They replace cracked or corroded components (no weld repairs like you'll find with the aftermarket guys). We replace the oil pump, the valve springs, and all fasteners. They apply new paint. And finish up with a process nobody in the aftermarket can or will do. Hot testing. They fire up the engine and run it for at least 15 minutes under pressure. See if the oil and coolant are doing their job. See if the engine performs to the same high standards as a new Mercruiser engine. And to make it official, they back it the same way. With the same Mercruiser one-year limited factory warranty.

We are proud to offer these factory remanufactured engines.

For more information or to place your order,
call 1-800-562-2742 and ask to speak to a marine engine technician.

Prices and specifications are subject to change without notice