The laser tack I used was made for model airplane engines and has a two blade and three blade setting. I used the two blade setting which required two strips of black tape be placed on opposite sides of the flywheel. Being hand held, you had to point it to the flywheel to get a reading. This could be a problem in rough water or heavy traffic where you needed to see where you were going. Using the Tiny tack on the Mercurys with a distributer requires using shielded ignition wires on all upper cylinders and reading off the bottom. . .
