[Rumble-Bee]

Superb workmanship & greatly simplified schematic made it easy for me to diagnose the problem after prior owner swapped in a 3.0 to replace the 2.7 in my 74 911. It turned out that I didn't need to leave the unit mounted -- the instructions, schematic, and LED allowed me to diagnose the problem which I was just too scared of "jumping" connections without the tach adapt, for fear of frying my tach. I just wish I had this when I converted 2 914-4's to 914-6's (years ago). Back then I made do with a crude arrangement of resistors after trial & error -- funny thing about that setup was that the tach would start at 0 RPM again and count up again whenever I reached red-line.