Choose 6K or 7K tach gauge for Mercury OB?

hkeiner

Lieutenant Junior Grade
Joined
Oct 17, 2006
Messages
1,055
I am planning to replace the tach gauge on my boat. I know that I need a gauge with a 12 pole setting with connections for 12v, send, and ground. However, I see that there are gauges that read up to 6K rpm and other gauges that go up to 7K rpm.

Is one gauge intended for outboards while the other one is intended for inboards? Is there any reason to choose a 7K gauge vs. a 6K gauge? The WOT range for my motor is 5,000 to 5,600 rpm, so I intuitively guess that either one would work OK.

Thanks for any advice.
 

jheron

Petty Officer 1st Class
Joined
Jul 21, 2004
Messages
284
Re: Choose 6K or 7K tach gauge for Mercury OB?

Either one will work :) 6K is all you need...
regards Jon
 

Texasmark

Supreme Mariner
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Dec 20, 2005
Messages
14,544
Re: Choose 6K or 7K tach gauge for Mercury OB?

8k. $88 at your Merc dealer. You don't want your needle pegged every time you go to WOT.

Mark
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
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May 19, 2001
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26,019
Re: Choose 6K or 7K tach gauge for Mercury OB?

Regardless of which you choose just make sure it a a good tach and accurate or it is not worth spending money on.
 

hkeiner

Lieutenant Junior Grade
Joined
Oct 17, 2006
Messages
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Re: Choose 6K or 7K tach gauge for Mercury OB?

8k. $88 at your Merc dealer. You don't want your needle pegged every time you go to WOT.

Mark

Taxasmark,

What do you mean when you say "pegged every time you go to WOT" ? I was planning on getting a Faria tach, as that was the brand of tach already on my boat. However, I would not want to get a tach that was not a good one. How does one tell if a tach would get "pegged" or not before buying it?

Thanks for the education on tachs
 

studlymandingo

Commander
Joined
Mar 22, 2006
Messages
2,716
Re: Choose 6K or 7K tach gauge for Mercury OB?

What Mark is saying is that a 6K tach would be almost maxxed out if you were to go to WOT, with an 8K tach, you would still have 2200 RPMs to go to max or "pegged out".​
 

hkeiner

Lieutenant Junior Grade
Joined
Oct 17, 2006
Messages
1,055
Re: Choose 6K or 7K tach gauge for Mercury OB?

Thanks. Now I understand and it makes sense to have a little extra room above the normal WOT rpm.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Re: Choose 6K or 7K tach gauge for Mercury OB?

Besides that instruments are calibrated at different places and usually Full Scale Deflection is not their most accurate positions, nor is the low end.

Mark
 
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