RPM gauge ? please help

[NO MO BEGGEN]

on the back of an rpm gauge theres a little slotted dial numbered 1,2,3,4. what is that for and how do you know what to set it on to make it read correctly. my engine is a 4 cylinder mercruiser 180

[HONDAM]

Its a trial and error thing is probably the easiest way to do it. You could waste a bunch of time trying to find somewhere to look it up or you could start up the motor and listen to the motor and try each position till you find the one that best fits your engine. I've installed dozens of those tachs and I just leave it at idle and choose the position that will give me about 600 to 800 rpms then rev it up and see if it acts appropriately.

Each change in position will about double the rpm reading on the gauges so its actually pretty obvious and takes just a few seconds.

[King Salmon 1]

Depending on the Manufacture of the Tachometer

1 - Outboard

2 - 4 cyl I/0

3 - 6 cyl I/0

4 - 8 cyl I/0

[HONDAM]

Depending on the Manufacture of the Tachometer

1 - Outboard

2 - 4 cyl I/0

3 - 6 cyl I/0

4 - 8 cyl I/0

I am sorry but this is NOT accurate. Depending on the different types of charging and ignition systems all outboards do not operate on the same setting. The I/O section could work, I don't know to tell you any different but im positive about the outboard.