I posted a question regarding the drive gearing of mechanical tachometers a couple of weeks ago.
The question was specific to my Alfetta, but I'm sure the answer applies to just about any 4 cylinder Alfa engine with a mechanical tach. It goes like this: The drive gear at the engine end is on the nose of the timing chain sprocket and rotates at one half crankshaft speed. This drive gear has seven teeth. The driven gear held in place in the bottom of the water pump casting has 14 teeth. My conclusion is that the drive cable for the tachometer rotates at 1/4 engine speed. George Graves put up a posting urging me to make sure it wasn't the speedometer that was inaccurate. This is a fair question, but I had already checked out speedometer accuracy using my TomTom satellite navigation device. I found it to be reasonably close to actual speed. George Beston Alfetta Spider Junior -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
