Purchasing a test tachometer

[mudd_mickey]

My OMC Service Manual states to use a test tachometer hooked directly to the engine and not use the tachometer which is in the instrument panel when testing/adjusting the motor.

What type of tachometer tool is it referring to? What kind of tool can I buy for this? Can I just buy an instument panel tachometer and hook it directly to the motor when I run my tests even though that doesn't seem logical?

I've googled like crazy and kind find the proper tool to use.

Thanks

 

[tashasdaddy]

Re: Purchasing a test tachometer

why not a timing light with the tach.