Mercury-Mercruiser 8M0187371 Quicksilver Longblock 5.7L V-8 91-97







New Quicksilver 5.7L 1991-97 Replacement Longblock

GM 5.7 Liter Non‑Gen + 350 V8
Left‑Hand / Standard Rotation
Replaces 1991‑1997 Sterndrive or Inboard 5.7L roller‑lifter marine engines

3 Year Limited Factory Warranty!  No core or container deposit!

Premium components
• 100% brass core plugs
• High volume oil pump
• Marine valve springs resist fatigue
• Super polished crankshafts using superior material and design features
Heavy duty head and block castings
• Resist corrosion and cracking
• Higher loading capacity
• Ability to use solid engine mounts
Hardened valve seat installed in the cylinder heads
• Hardened Intake & Exhaust seat inserts
• Premium alloy seat material
Black‑X Valve Technology
• 21N Intake valve parent material
• 24N Exhaust valve parent material
• Plasma nitride prevents valve sticking & increases toughness
• Chrome‑Cobalt alloy seats resist corrosion from alcohol fuels
• Valve life improved 42%
100% Advanced SIM Testing
• Water and oil passages pressure tested 100%
• Phased rotational testing with hot oil validates all oil passages, bearings, and assembly
• Advanced compression testing verifies cylinder sealing and valve lash integrity
• Oil flush at completion of test removes break‑in debris
• Shipped without oil to prevent spillage while in transit