I have installed a new tachometer, and it seems that it is reading less than it should. I also just installed new alternator. Is it possible that due to different pulley size on alt. that the tach would be off? The pulley is in fact larger than original.
the tach should have dip switches that will allow you to adjust the output for various pulses per rotation.
but yes, the pulley will affect the alternator speed, decreasing the number of pulses sent to the tach.