Author Topic: Calibrate Tachometer  (Read 263 times)


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    • ReallyReilley
    • KennethReilley
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Calibrate Tachometer
« on: March 09, 2018, 04:47:10 PM »
Just getting to know our new-2-us 2012 MX185 / 4.3 MPI / 220hp / 1.81 Alpha and 23P prop.

There is clearly an issue with the tach because at almost WOT it was reading 6,000 rpm. I confirmed with Mercury Tech Support this morning that my engine is rev limited at 4950, so it couldn't have possibly been turning 6k. The switch on the back of the gauge is set to 2 (for 6 cyl) but it was still reading wrong, so maybe there's some corrosion in there or... I dunno. Here's my question:

Can I play around with the settings and calibration knob and accurately calibrate the tach while running on the hose / muffs at home? I confirmed with the Merc tech this morning that at idle she should turn 625 in neutral, 650 in gear... so if I get the tach set right and then dial it in a 625 rpm at idle in neutral at home, will that translate into an accurate reading out on the water?

Note; I'd explain why I have to do it with this way, but it's a really long story... I have a second post asking questions about that problem. You're welcome to help out on that problem too, if you want  :-[
2012 Glastron MX 185, 4.3 220HP
2004 Newmar Mountain Aire 4302