1971 25hp Evinrude-help with Tachometer

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tankdawg

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Joined
Mar 24, 2009
Messages
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I looked pretty hard at previous posts to see if my answer already existed but did not find it. I want to install a tach on my boat. I have all of the controls mounted in a console with steering & electric start about 6 feet from the motor so I am pretty sure I will need to jump off of one of the wires at the kill switch. My question is specifically what analog tach works well for this application. I am really not interested in a digital tach since they don't respond well to fluctuating rpms. I want something in the 2-3" range with backlight if possible. I hope I am not sounding to picky.
 
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R.Johnson

Rear Admiral
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Sep 24, 2003
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4,446
Re: 1971 25hp Evinrude-help with Tachometer

The only tach I have heard of is a tiny tach mentioned on this board, I have never seen one. I know of no other for that magneto ignition.
 
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F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: 1971 25hp Evinrude-help with Tachometer

OMC made magneto-driven tachs for those motors---back in those days. But they are no longer made and seem to be pretty rare. All modern tachs are driven by the alternator. And of course your 25 doesn't have an alternator. Better keep an eye on e-bay.

Or settle for a Tiny Tach digital, driven by a spark plug wire.
 
T

tankdawg

Cadet
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Mar 24, 2009
Messages
6
Re: 1971 25hp Evinrude-help with Tachometer

I think I found what I am looking for. It is Equus model 8068. It will work on all ignition systems, 2 or 4 stroke and 1 to 12 cylinders. They also offer a inductive pickup but I think there would be too much interference for that. Best of all I found it in town for only $70.
 
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tankdawg

Cadet
Joined
Mar 24, 2009
Messages
6
Re: 1971 25hp Evinrude-help with Tachometer

I bought and hooked up the tach last night. I used one of the shorting switch wires for my signal. The tach was very irractic. I assume there is a lot of induction into those wires. I came up with some CAT5 shielded wire and have installed it but not yet tested. I wil post another update sometime this weekend or Monday.
 
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tankdawg

Cadet
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Mar 24, 2009
Messages
6
Re: 1971 25hp Evinrude-help with Tachometer

I am beginning to wonder if it was a good thing I was done fathering children before I got my boat. I hooked the tach up to several different point and grounded the shielding. There is just too much EMI to get an accurate reading. I am taking the tach back today. I am not even sure a tiny tach would work in the magnetic blender I have. I am thinking it might be better if I replace the coils and plug wires but it runs fine. Any insight here would be greatly appreciated. My goal is to experiment with my 9x9 and 9.25x11 props to see which offers the best power at the optimum rpm with different loads.
 
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