overheating issues

440s have air pocket issues, make sure the radiator fill point is the highest point in the system. If the temp guage isnt fluctuating wildly then you probably dont have an air pocket, the thermostats have a tiny weep hole in em to bleed air out but it takes awhile. The hot water in the radiator needs to have a chance to cool down so it could be a fan issue or maybe the motor is running way lean.