A strong, rigid and accurate tool to position the forward edge of the cowl to achieve a perfect fit without needing to have a propeller installed.   It is so simple that you cannot make a mistake setting the proper dimension.  The tool can be removed and reinstalled in minutes returning to the exact same position, every time.   Fits 3/8, 7/16, 1/2-inch propeller bushings flanges.   Total tool weight = 6 lb (2.7 kg). 
 
Note:  If it is an older 3/8-inch bolt style with long bushings and the flywheel is not installed, use 2 spacer plates and adjust flywheel to spinner spacer distance by 0.25 inch.  This is so the mounting base has adequate bushing clearance to bolt.   
 
1. Input spinner outer diameter - for aluminum plate outer diameter
2. Input desired sag compensation value - for rubber engine mount sag.  This alters the aluminum plates and shifts the cowl downwards. 
3. Input flywheel to spinner distance less the desired spinner to cowl gap - to set the spacer length
4. If the flywheel is not installed - select flywheel spacer plate to simulate it as distances are measured from the flywheel