i have heated the gear hotter than 350 before. i believe the number is closer to 500 degrees. i also keep a propane torch close by to keep the heat up. the torch is the kind you use to sweat copper pipes. if the gear does not slide on all the way with some persuasion with a block of wood and a hammer add more heat with the torch quickly and send it home with the hammer again. at worst you will ruin the timing gear. but it may save you from pulling the motor. besure to check the cam front to rear movement before reassembly. tom