1982 Ski-Doo Shop Manual, Page 105Get this manual
SECTION 02 ENGIN SU B-SECTION 05 (464 ENGIN TYPE )
For example: 150 opening 49 closing Using angle finder, mark crankcase at 150 from bottom edge of magneto side inlet port
To correctly install the rotary valve disc proceed as follows:Turning crankshaft counter-clockwise, (drive pulley side) bring magneto side piston to Top Dead Center using T.O.C gauge- Position the rota ry valve disc on gear to have edges as close as possible to the marksNOTE: The rotary valve disc is asymmetrical, therefore, at assembly, try positioning each side of disc on gear to determine best installation position