Un-screw one flywheel to crank bolt... Screw in the long bolt, lock it down by tightening the nut... slip the sleeve with the indicator attached over the long bolt, position it so the indicator is 90 degrees the crankshaft, lock the sleeve by tightening the little socket head cap screw... adjust the indicator for the best alignment & tighten the last two bolts... Sweep the bore & take your readings... It's a good idea to repeat the sweep to verify repeatability... Which is the whole point of the tool, it's solid, doesn't move around therefore repeats consistently...