85 engine electrical.pdf - Vintage Snow

ENGINE ELECTRICALTypical 1985 - Current Timing Advance CurvesIgnition TimingMAXIMUM ADVANCEOPERATINGRPM(DEPENDINGON ENGINE)SEE DATA1000 2000 3000 4000 5000 60007000 8000RPMNOTE: Always verify timing of engine at room temperature only (68 0F/20° C).The ignition maximum advance is at or near 3000 RPM on all current style ignition systems. Verify the ignitionposition at maximum advance when checking the timing.If engine damage has occurred due to a suspected ignition related problem, check the ignition timing at thespecified operating RPM.Due to differences between engines, it is necessary to dial indicate the timing marks on all engines beforeattempting to adjust the ignition timing. To indicate the marks:1. Remove the mag cy~nder spark plug and install the dial indicator.2. Rotate the cranRsbaft by hand while observing the dial indicator. As the piston touches the indicator plunger,the dial will begi~tO'rotate. Find the pOint where the pointer stops rotating and reverses direction. This will beTDC (Top Dead Ceri'mJ").3. While holding the crankshaft with the pi~ton at TDC, zero the indicator by rotating the bezel until the 0 on thedial and the pointer align.4. Rotate the crankshaft opposite the direction of rotation about .250 BTDC (2 1/2 pOinter revolutions).5. Determine the correct ignition timing position fromthe ignition data charts and rotate the crankshaft inthe normal direction of rotation to that position.(Example: 1993 EC50PM-01 engine timing is.150 BTDC. The crankshaft must be rotated in thenormal direction of rotation so that the dial indicatorpointer does one complete revolution and stops on50. This should be 1 1/2 pointer revolutions beforetop center, or .150 BTDC..I'6. While holding the crankshaft at the correct timingposition, determine which of the rotating andstationary timing lines align. Mark these lines withchalk or a marker to make them easier to identifywhen you are doing the running timing.8/94 4.12