How to Mount a 1966 Mercury Outboard Motor

Low-horsepower 1966 Mercury motors -- those of less than 50 horsepower -- are mounted using Cheeseborough-type clamps that have a second bolt securing the clamp bolt. Outboards producing between 50 and 70 horsepower are mounted to a boat's transom using two 1 inch bolts. Those producing 70 or more horsepower require a total of four 1 inch bolts because they are both heavier and produce higher torque than smaller earlier models.

Things You'll Need

  • 4, 1 inch Mercury Marine engine mounting bolts
  • 4, 1 inch stainless steel flat washers
  • 4, 1 inch stainless steel lock washers
  • 4, 1 inch Mercury Marine mounting bolt nuts
  • Shop crane or overhead lifting device
  • Torque wrench
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Instructions

  1. Thirty Horsepower and Less

    • 1

      Place the clamps of the motor over the transom of the boat. Move the outboard so the clamps are equidistant from the centerline of the boat.

    • 2

      Turn the 9/16 inch clamp bolt on each of the clamps so that the motor is held in position. Tighten the 1/4 inch pan bolt on the side of the clamp to prevent the clamp bolt from loosening.

    • 3

      Attach the safety chain, welded to the frame of the outboard, to the safety bolt within the boat.

    Mid-Horse Power with Two Bolts

    • 4

      Raise the motor to the center of the boat's transom. Slip the mounting bracket over the transom

    • 5

      Slide two 1 inch Mercury Marine engine mounting bolts through the 1 inch stainless steel flat washers. Slide the bolts through the mounting holes in the bracket and the transom.

    • 6

      Slip additional a 1 inch stainless steel lock washer over the end of each mounting bolt. Thread nuts onto the mounting bolts. Tighten the bolts to 55 foot-pounds of torque with a torque wrench.

    Motors of 50 Horsepower or More

    • 7

      Move the motor into place over the transom of the boat, using a shop crane or overhead lifting equipment.

    • 8

      Position the motor over the center of the boat's transom. Lower the motor into place on the transom.

    • 9

      Insert two 1 inch Mercury Marine engine mounting bolts through 1 inch stainless steel flat washers. Fit the top two bolts through the mounting holes. The large horsepower motors require four bolts -- two top and two bottom -- because of the additional torque created by these motors. In reverse, a high-horsepower 1966 Mercury would pull the motor down and under the transom.

    • 10

      Fit two additional 1 inch Mercury Marine engine mounting bolts through the bottom two mounting bolts through the mounting holes in the mounting bracket and transom. Place 1 inch stainless steel lock washers over the ends of all four bolts.

    • 11

      Thread 1 inch Mercury Marine engine mounting nuts onto the mounting bolts. Tighten the nuts to 55 foot-pounds with a torque wrench.