tractor cranks but won't start?

craftsman lt4000 with kohler 14hp engine. #917255450 motor quit abruptly and mid-range rpm,sounded like it threw the rod.
Motor was locked in one position,I turn it counter clock wise and it turned. Checked the piston by taking out the plug. Piston went up and down as it should. check for spark,OK. Check compression,OK. Fuel delivery not an issue. Took oil pan off and found that the ACS assembly imploded. Replace camshaft.All timing marks lined up,no damage to crank,rod,or piston or cylinder wall. Thought maybe the flywheel key got sheared off when the motor quit,NOPE.
150lbs compression,spark and fuel all there Carb safety solenoid on float bowl working properly.What have I missed?

workaholic
October 2014