Different way to set max timing?

[Dave1027]

I have always wondered about the max timing setting on my '88 100 hp Merc. There is an adjustable pointer on the flywheel cover that I could never confirm was set correct. You need a special tool to set it. I had set my max timing by that pointer according what the manual stated it should be.

Since I like to tweak and fool around with things I decided to try something new. With the boat in the water I started the engine and let it idle in neutral. I increased the idle timing till the rpms stopped increasing and then set my max timing to that setting. I have no idea what the BTDC setting it is but it is less that what I had it set to using a timing light and the flywheel cover pointer.

I then tested the motor out on the open water, making several high speed runs. I was amazed that I had more power and higher top speed. I'm curious what the experts think of this method.

 

[Chris1956]

Sounds like a good way to destroy your motor.

Max spark advance can be set on land, just by cranking the motor with all but #1 spark plug removed, and the prop removed. Simply set throttle to max and crank motor in gear, by jumpering the starter solenoid.

The timing pointer can be set accurately with a dial indicator, caliper or even a steel ruler and some math.