Piston Ring 39-18653A1 

Piston Ring (ø 2.565 +.015) replaces MerCruiser part # 39-18653A1

All rings come 2 to a set

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

Crossflow: The oldest design, and the one used on Mercury / Mariner /Force 35-150 HP engines from 1970-1990 is the crossflow piston. As the air / fuel mixture travels through the transfer port and into the cylinder, a deflector, cast into the top of the piston, directs the air / fuel mixture towards the combustion chamber and spark plug tip for maximum efficiency. All engines with deflectors on top of the pistons will be crossflow engines. External inspection of a crossflow engine will reveal removeable transfer port covers on the side of the cylinders.