We all seem to agree that we can’t find a torque number but there is a locking plate that goes on with the fan and fan balancing pieces all of which are secured with the fan bolts. So the lock plate prevents the bolt loosening, but get it tight as you can to start. Moss #837-580 Lockplate, crank bolt https://mossmotors.smugmug.com/search#q=837-580 Allen TR4