1978 Ski-Doo Shop Manual, Page 135Get this manual
SECTION 04 SUB-SECTION 02 (ENGINES) (Torque to 20 Nom (15 It-lbslAt assembly on crankcase apply Loctite Lock'n Seal 242 on threadsTorque to 35 Nom (26 tt-lbslTorque to 20 N.m (15 ft-Ibs)
To remove or install magneto retaining nut, lock crankshaft in position with special hold-on support as illustrated(See Tool Section)
Hold-on support