High Output Alternator & My Tachometer

[Rich Lemieux]

I have just installed a high output alternator & regulator on our 1997 Catalina 36 MK II. The engine is a 1997 Universal M-35B diesel. The tachometer is reading about 300 RPM higher then it should. I understand this is due to the new alternator which has 14 poles (or maybe 7?) and a 2 5/8" pulley.My questions are as follows:The tachometer has DIP (14 I think) switches on the back to correct the error. Do you know what the setting should be?I understand the tachometer can be driven by a RPM Sensor on the engine not associated with the alternator. Is this true for my engine and what should I ask for to do this?Thanks Rich

[Tom Senator]

And what is your RPM at full throttle while motoring ? Maybe that is the speed of the engine when the alternator is not producing current.

[Rich Lemieux]

Hi Tom...My only reference is at idle which is at 1300 RPMs vs 1000 RPM before I installed the alternator. This weekend I ran the engine at 3000 RPMs on the Tach but it appear