funny tach readings

[phatmanmike]

just bought my first tach, installed it, turns on properly and all wiring is good. it is teleflex #58475 . im using it on 1980 evinrude 50 hp 2cyl. on the back it has 3 big, like inch long screws out the back that the wires attach to, and thats it. when on the boat.. it idles at 3500 and as soon as i accelerate it goes all the way around and stops at zero... it has NO dial or switch on the back to set... anybody seen this before?

 

[Hooty]

Re: funny tach readings

That tach will not work on your engine. It's make for a four pole alternator only.<br /><br />c/6<br />Hooty