I'm trying to figure out the relationship between engine speed and the drive speed of a mechanical tachometer.
My Alfetta's tach has been unreasonably inaccurate for some time. At 70 mph it reads 4200 rpm when it should read 3500. I have the tach out of the car to play with as a winter project. There's no easy way of making any adjustment to it that I can see. Before I take it to an instrument technician, I want to know what the relationship is between the cable rpm and engine rpm. My best guess is that the cable rotates at one half of engine speed, because it's driven off the intermediate sprocket of the timing chain system. I doesn't look like cable speed is geared up or down at the water pump fitting, but I don't know for sure. Has anyone been there / done that and figured this out already? Your advice could save me some valuable time! George Beston Spider Jr. Alfetta Berlina -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
