1970-1979 Ski-Doo Snowmobiles Service Manual, Page 134Get this manual
POWER TRAIN NOTE: If proper pulley alignment cannot be achieved through adjustment and the use of the proper number of shims, inspect drive components as well as frame for possible damage
Check alignment whenever engine is installed or rapid beltwear is experiencedAlignment (1970-1973 Models) 1Remove drive belt2Check that engine mount nuts are torqued to 33-35 ftlb(4.6-4.8 mkg)3Using appropriate adjuster bar, check pulley offset as specified in Table 3See Figure 24dOn later models, chaincases with external tensioner bolt, tighten adjuster bolt for V4 in(6.4mm) slack measured at driven pulley (Figure 23)
Pulley offset