Tachometer not set up correctly?

[R055]

Hello, was setting up my head unit and took a peak at the tachometer and seems it's set to 8 cylinders instead of 6?(I have a mercruiser 4.3) can you guys confirm that the arrow is suppose to be pointed at the 2 instead of the 3? Why is there a total of 6 options?

Also how big of a difference would making it run in 8 cylinder mode at idle be? My idle is locked in at 600 with the tach in 8 cylinder mode.

 

[Alumarine]

It does look like it's set incorrectly.
If you change it, rotate it back and forth (not too far) several times to help clean the contacts.

If set incorrectly it will impact the reading.

 

[Silvertip]

Tachometers are somewhat universal. Outboards use a magneto ignition/electrical system which gets it's power from a stator with a specific number of poles. Settings 5P, 6P etc stand for the number of "pulses" from the stator. Auto type engines such as yours have a battery ignition system and tach pulses are derived from the ignition system. A 4.3 so 4, 6, and 8 cylinder settings are provided for them. Since the tach is set for 8 cylinders it is reading low since it is only getting 3/4 of the pulses it is expecting. You may also be over-reving on the high end so it is best to get this situation rectified.