Sierra 18-2950 Head Gasket - Replaces 309612, 766870 - Johnson/Evinrude 9.5 HP Outboards 1964-1973

The Sierra 18-2950 is a head gasket engineered for Johnson and Evinrude 9.5 HP outboard engines built from 1964 to 1973. It seals the cylinder head to the power head, maintaining compression and preventing coolant or combustion leakage at the head joint, which is essential to reliable engine operation on these older Johnson/Evinrude 9.5 HP outboards. The gasket is manufactured to meet or exceed the fit and performance of the original equipment part it replaces, directly interchanging with Johnson/Evinrude OEM numbers 309612 and 766870. The 18-2950 is sold as a package of 2 head gaskets, making it a practical choice for shops or owners servicing more than one power head or keeping a spare on hand. Because it is designed specifically around the dimensions and bolt pattern of the original 9.5 HP power head, it installs as a direct replacement without modification. Whether performing a routine power head rebuild, addressing a compression loss issue, or doing preventive maintenance on a vintage Johnson or Evinrude 9.5 HP outboard, the 18-2950 provides an exact-fit, OEM-equivalent seal.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2950
• Package Quantity: 2 head gaskets per package
• Replaces (OEM): 309612, 766870
• Fitment: Johnson/Evinrude 9.5 HP outboards (1964-1973)
• Weight: 0.07 pounds
• UPC: 030999314505
• Product Type: Head Gasket

Fitment

• Johnson/Evinrude 9.5 HP outboards (1964-1973)

Replaces (OEM)

• 309612
• 766870

Frequently Asked Questions

What engines does the Sierra 18-2950 head gasket fit? The 18-2950 is designed for Johnson and Evinrude 9.5 HP outboard engines built from 1964 to 1973.

What OEM part numbers does the 18-2950 replace? It directly replaces Johnson/Evinrude OEM numbers 309612 and 766870.

How many gaskets come in a package? The Sierra 18-2950 is sold as a package of 2 head gaskets.

How much does the 18-2950 head gasket weigh? Each package weighs 0.07 pounds.

Is the Sierra 18-2950 an OEM or aftermarket part? It is an aftermarket head gasket manufactured by Sierra to meet or exceed the specifications of the original Johnson/Evinrude 309612 and 766870 head gaskets.

Will the 18-2950 fit a newer Johnson or Evinrude outboard? No, the 18-2950 is specified for Johnson/Evinrude 9.5 HP outboards from 1964 to 1973 only; newer power heads use a different head gasket.

What does the head gasket do on a 9.5 HP Johnson/Evinrude outboard? It seals the joint between the cylinder head and power head on the 9.5 HP engine, maintaining compression and preventing coolant or combustion leaks.

What is included when you order the 18-2950? The order includes a package of 2 Sierra 18-2950 head gaskets, with no additional hardware.

Is 18-2950 the correct part if my old gasket is stamped 309612? Yes, the Sierra 18-2950 is the direct replacement for a Johnson/Evinrude 309612 head gasket.

Is 18-2950 the correct part if my old gasket is stamped 766870? Yes, the Sierra 18-2950 also replaces the Johnson/Evinrude 766870 head gasket.

Can the 18-2950 be reused after removal? Head gaskets, including the 18-2950, are designed as a one-time seal and should be replaced with a new gasket any time the cylinder head is removed.