Tiny tach question

[tmcalavy]

Got my tiny tach today. Hooked it up with red wire wrapped around top spark plug wire on my 4 cyl Merc 500 50 hp...tach read four digits, first two were 57. Now my manual says the Merc idles at 550 to 600 rpm. The tiny tach is for two cylinder engines. Do I need to divide its readings by 2 or 4, or did I get the wrong model...should I have gotten one for 1cylinder engines? Or am i reading the display incorrectly? Help from anyone is appreciated.

 

[FlyBoyMark]

Re: Tiny tach question

Tiny Tach also manufactures 3 models exclusively for Mercury..known as "Service Monitor" and alternates between hours and tach via a membrane button on the face. These particular models are slightly different than the actual Tiny Tach brand. The Mercury versions compensate on certain models for outboards that fire every 180' or 360' or 4 stroke so that you get the proper RPM readout. Did you consult with Tiny Tach first before buying?...They answer their emails very quickly. The cables can be extended to 25' if you can locate the tiny shielded cable they use and the micro shielded connectors. I extended mine to 15' and had to increase the wraps to 7 turns instead of 2 to make it work (using Mercury version)