P = 97 on tachometer

Nov 26, 2012
1,653
Hunter 34 Berkeley
The tachometer that goes along with my Yanmar 3GM30f has P=97 on the face. What does this mean and must a new tach also be a P=97?
 
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Boffin

.
Aug 30, 2010
80
yahama 25 Hong Kong
It means the meter count the sensor from the engine of 97pulse per rev.. yes you have to set the tachometer at pulse mode of 97/rev.
 
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Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
What does this mean and must a new tach also be a P=97?
NO ! Absolutely not !

Later model electronic programmable VDO tachs will read anything ................. flywheel output, alternator output, distributor output (gasoline), heartbeat and heart pacemakers will provide a useable signal. Pacemakers can be problematic if a pretty girl walks by.

The tach I installed about ten years ago is the VDO Vision 333-163. You can set it up by calculation but it takes only seconds to set it up and calibrate with a cheap optical tachometer. Be careful that the VDO face matches the hole left behind by the old tach. If so, there are other makes of tachs which may fit.
 

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Boffin

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Aug 30, 2010
80
yahama 25 Hong Kong
if you don't have an extra tachometer for calibration, set the VDO tachometer to pulse mode ,then set p=97. That would be OK. The flywheel of Yanmar 3GM given 97 pluse per rev.to the sensor then to the tachometer as reference. or you can go to the adj mode to cal by an individual tachometer . Yanmar has a technical bulletin no. MSN 03 -015 telling the procedure for PULSE mode setting