Screw @5

Mercury Screw (M12-5/16-18 × 1 ⅜ in) – 10-8M0214949

It’s easy to overlook a single bolt—until a loose intake starts whistling or a fuel rail seeps at the gasket. This genuine Mercury screw anchors the lower Vortec-style manifold on 4.3-, 5.0-, and 5.7-liter MerCruiser blocks (and replaces legacy part 10-808010), providing the clamping force that keeps air, fuel, and cooling passages sealed tight even when you’re bouncing through three-foot chop.

Built for marine mayhem:

• Rolled 5/16-18 threads bite cleanly into aluminum without galling, then hold torque despite vibration.

• 1 ⅜-inch shank reaches deep bosses, distributing load so gaskets stay flat.

• High-tensile alloy steel treated with a dual zinc-nickel finish to shrug off salt, fuel, and the occasional coolant splash.

• Standard ½-inch hex head matches the socket already in your onboard tool roll.

Whether you’re buttoning up a fresh manifold install or swapping a scarred fastener during winter service, drop in the screw Mercury spec’d and forget about it. A couple of dollars today can save you from hunting down vacuum leaks or cooling-jacket dribbles when you’d rather be trimming out and chasing the next point.