Piston Ring 39-78918A4 

Piston Ring (ø 3.125 +.015) replaces Mercury/Mariner/Force part # 39-78918A4

GLM’S EXCLUSIVE MARINE PISTONS
• Fully Machined Hypereutectic Pistons
• Featuring a Hard Anodizing Coating on Top
• Resisting Temperatures up to 1560°F
• Hardness: HV280-400
• Pistons are T-6 Heat Treated

Loopcharged: In 1976 Mercury / Mariner /Force introduced a V6 engine with loopcharged pistons. This engine was the V-175 HP 6-Cylinder. A loopcharged engine has a transfer port cast into the cylinder wall in such a way that it will direct the air / fuel mixture towards the combustion chamber and spark plug tip without the need for a piston deflector. All engines with a flat top or a slight dome on the top of the pistons will be loopcharged. Loopcharged engines will not have removable transfer port covers on the side of the cylinders.