Even overhauled tachs have a 200 to 400 rpm error!!! That is why you get an electric tach! I have replaced the mechanical tach for a new electric tach in about 12 planes now. EACH owner says, "Why didn't I do this sooner!"
You can get a stand alone EI R-1 electric tach for about $400.00. You spend almost that much for an overhaul on your outdated mechanical tach! Do the math again...
What he just said. The EI tach is by far the best bang for the buck and is far superior to any mechanical tach.....even the newly overhauled ones as the tach drive cable system is suspect and problematic as well.
