To each their own, of course, but I use my tach every time I set up an engine. It is tough to tell 6500rpm from 6700rpm on a big gas engine or 10500rpm from 10900rpm on a glow model by ear in my opinion. Also, I find it nice to have a baseline in case one day your engine doesn't sound right you can tach it and see if it is just your ear or if you have a problem.

I use a TNC tach which is now distributed by Fromeco. The tach is regarded as one of the best in the industry and was designed by a no-BS engineer. Mine is a "tweaked" model as I knew TNC (Tony N. Criscimagna) very well. Check out a list of his other inventions below, how about the plasma screen!

http://www.patentgenius.com/invented...odstockNY.html