How to Adjust the Timing on a Mercury 1150 Hp Outboard Motor

The Mercury Outboard is one of the more popular motors, as is the 1150 hp version. Many owners have problems when it comes to adjusting the timing on this model, in part because the manual makes things a little confusing. The steps are actually easy to accomplish and the only tool really needed is a dial indicator. This helps adjust both the belt and the timing pointer.

Find the cowling covering the power head and remove it to reach the timing belt. The spark plugs also need to come off to adjust the timing belt. Look for the dot on the flywheel. This dot is the alignment mark.

Remove the exterior parts surrounding the timing belt, including the washers, pulley cove and bolt before taking off the timing belt. Use a clockwise motion to twist the flywheel, keeping one eye on the alignment mark or dot. When this dot matches up with the middle of the distributor shaft, stop turning.

Turn the distributor pulley until the arrow mark on it reaches the dot on the flywheel. Add the new belt and attach the washers, blot and pulley cover. You can also adjust the torque during this step.

Locate the first spark plug opening on the motor and attach a dial indicator. Move the dial indicator to the 0 position and turn the flywheel. Keep turning the flywheel to the left until the dial indicator just passes the .464 mark. Then turn it to the right and stop when it reaches this same mark.

Turn the timing pointer in a clockwise direction until you see the pointer meet the .464 mark. Now you can take out the dial indicator and add new spark plugs. The timing on your outboard motor is now complete.


  • Always consult your manual if you have any problems adjusting the timing. All of the steps are clearly laid out inside the manual.


  • The .464 mark refers to the position of the crankshaft. The mark itself is located on the outside edge of the dial indicator.

About the Author

Jennifer Eblin has been a full-time freelance writer since 2006. Her work has appeared on several websites, including Tool Box Tales and Zonder. Eblin received a master's degree in historic preservation from the Savannah College of Art and Design.