Tach for 1GM10

[Ken13559]

Hello and A Merry Christmas to All who celebrate and a Happy Holiday to All who enjoy it.
I'm looking to fit a Tach for my friend's H280. He has a Yanmar 1GM10. Is there a Tach option for this engine? If not is there a 3rd party (after market) one that can be fitted either to the crank shaft/pulley or prop shaft?

 

[Ralph Johnstone]

This Thing is So Versatile for Input ..........

......................... it'll read the output from your pacemaker (if you've got one).

http://forums.sbo.sailboatowners.com/showthread.php?p=896626&highlight=tachometer


Use your alternator as the sensor.

 

[Ken13559]

Ralph, thanks. I don't know if there AC signal out from the Yanmar stock Hitachi alternator. Any idea ?

 

[Paul F]

If there is not a tach signal output on the alternator, one can be added easily at an alternator rebuild shop for little money. Also, you might be able to pick up a tach at good boat salvage yard. I got one years ago for my 2QM15 for $20. You have to tell them that is all they are worth used. It had a large 4" face and worked well.

 

[Ralph Johnstone]

You should be able to use the pulsing DC output from your alternator if you don't have anything exotic like an external smart alternator regulator. See the attached Ample Power article.

The only problem is that you need to beg, borrow, or steal a hand held tach to set up the new VDO tach as there are a few stumbling blocks along the way such as pulley ratios, number of poles, etc.

Not the most accurate solution available but quite likely the most cost effective if you don't mind a +/- 1% error.

 

[Paul F]

A tach can be calibrated using a fluorescent light's strobing effect. Mark the fly-wheel with chalk at 0 and 180 degrees on the wheel. Under a fluorescent light an engine spinning at 1800 rpm will show a steady chalk line. The tach can be then adjusted to 1800 rpm.

 

[kbuckley]

I installed a TinyTach on my YSM12, it uses a sensor that clamps over the fuel line to the injector and requires no calibration. Trivial to install and has a digital readout. Just Google it to find.

Ken

 

[Ralph Johnstone]

My Kind of Thinking ....................

A tach can be calibrated using a fluorescent light's strobing effect. Mark the fly-wheel with chalk at 0 and 180 degrees on the wheel. Under a fluorescent light an engine spinning at 1800 rpm will show a steady chalk line. The tach can be then adjusted to 1800 rpm.

.............. right back to basics and every bit as good as a hand held tach.

You should also get a second point in there to be sure the tach is linear. After calibrating at 1800 RPM with one solid stationary line across the crank sheave, slow the engine down until the tach reads 900 RPM and check the sheave to ensure it now shows two solid stationary lines across it at 90 degrees to each other. Just to be sure you've checked out the entire range of the tach, increase the revs to 3600 RPM on the tach (if the engine is rated for that) and ensure you are back to one solid stationary line across the sheave.

Another project ticked off the list.