It needs to run about 5000 rpm's in order to correctly time a crossflow. Due to ignition timing creep at higher rpm's. The factory sold timing wheel props to the dealers to load test in dealer water test tanks. You can probably use a test tank and a shaved prop, or dunk the lower unit under water (when the boat is on the trailer at the local boat ramp) and run it with just the lower unit submerged. Same thing. The engine needs to be under load during this timing process. You can also time it statically, using the Joe Reeves method. Found in the "top secret" file at the top of this page.
