Engine Speed for M25

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Doug

Several years ago, I purchased a 1985 Cat 30, with the Universal M25 diesel. The alternator was weak when I got it and shortly afterward it died altogether. I had it rebuilt at a local automotive alternator and starter repair shop and it seems to be working just fine. The tach only indicates a max RPM of about 2100 unloaded, and 2000 loaded. 2k will move Serenity along at about 6 knots (gps measured), but the engine sounds wound up tight. The question is: am I getting a correct reading off the tach?
 
G

Gordon Torresen

Unwind

Six knots in a 30 is wound up tight. Your tach is definately off. If you open the throttle (short term) in neutral, the max RPM will be 3000. Idle will be around 700. Most tachs can be calibrated with a potentiometer or dip switches on the back of the display. Be sure the alternator belt is tight and tweek the adjustment until you come closer. A hand held tach can be used if you want more precision.
 
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