FOR SALE 1990 MerCruiser Boat engine motor 5.7 L 350 Mag Magnum FRESH WATER 412 hrs. This engine very excellent condition and great runs.

The 1990 MerCruiser 350 Mag (5.7L) is a marinized General Motors small-block V8 engine. Built for high-performance sterndrive and inboard applications, it typically produced 270 horsepower and features a classic Chevy 350 foundation.

Engine Specifications

• Engine Type : GM Small Block V8
• Displacement : 350 CID / 5.7 Liters
• Horsepower : 230 HP to 270 HP (varies by 2-barrel or 4-barrel carburetor spec)
• Bore & Stroke : 4.00″ × 3.48″ (102mm × 88mm)
• Compression Ratio : 9.3:1 or 9.4:1
• Max RPM Range (WOT) : 4,400 to 4,800 RPM
• Idle RPM (Neutral) : Approx. 650 RPM
• Oil Pressure : 30 – 60 psi @ 2,000 RPM
• Oil Capacity : 5.5 to 6 Quarts (with filter)
• Fuel Requirement : 87 Octane

Key Mechanical Details

• Block Design : In 1990, the 350 Mag utilized a cast-iron block, usually featuring a 1-piece rear main seal and the dipstick located on the starboard (right) side.
• Ignition : Standardly equipped with the highly reliable Thunderbolt V ignition system (or Thunderbolt IV in earlier versions).
  Fuel Delivery : Typically carbureted using either a Rochester Quadrajet 4-barrel system.