Thread: Tach Adjustment
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Old 11-25-2016, 06:38 PM   #13
High Wire
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City: Cape May, NJ
Vessel Name: Irish Lady
Vessel Model: Monk 36
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The tach could be correct for what it is measuring.
Use your photo tach to measure crankshaft speed and alternator speed.
Alt speed / Crank speed gives you a number like 2.763. This is the speed ratio between the crank and alternator. Do this at 1000 rpm, whatever midscale is on the tach, and a higher speed like 2500. Compare ratios for both engines to make sure they are the same. I would guess the port side is numerically higher meaning faster turning alternator for a given engine RPM.
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Archie
Irish Lady
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