1970-1979 Ski-Doo Snowmobiles Service Manual, Page 31Get this manual
CHAPTER TWO
4Carefully examine points and dress with file or replace as necessary5Loosen screw securing breaker pointsUsing feeler gauge set breaker point gap to 0.014-0.018 in(0.35-0.45mm)Tighten screw securing breaker pointsRecheck gap as gap can change when screw is tightened, readjust if necessary6Disconnect electrical junction block at engine and connect flashlight-type or tonetype timing testerConnect one lead to black wire leading from engine and the other lead to good ground such as fan cowlNOTE: More precise timing can be achieved by using dial indicator-type gauge as described in Chapter OneIf dial indicator gauge is used proceed to Step 9If gauge is not used perform next step