Tachometer Accuracy

[Summett]

I have a Merc 3.0LX and i'm concerned about the accuracy of my Tach gauge. My concern is that when i'm at full throttle my tach says i'm running at 5400 rpms, which seems high (recommended is 4600 - 4800 rpms). However, when i turn my engine completely off the tach needle seems to rest at the 200 rpm mark and not at completely zero (which i know would still make my rpms high, but if i know the tach is correct then i'm comfortable making the necessary changes to lower the rpms).

Is there a way to check the accuracy of my tach, or reset it, etc.? It is not a digital one, it is a standard dial tach.

Your help is appreciated!

 

[Don S]

Re: Tachometer Accuracy

Compare it to a shop tach.
Many timing lights, dwell meters, have tachs built in. There are also stand alone photo tachs that read a reflective tape you put on the crankshaft pulley.