I still haven't gotten my Smith tach to work. In the meantime, has anyone worked out RPM vs. MPH for a 3.3:1 final drive w/ 10" wheels? Specifically, I'd like to know the MPH in 1st, 2nd, 3rd & 4th gear @ 6000 RPM. Thanks!
I had problems with one too, had to replace the wiring loom and connector that attaches to the tach....it had continuity on all pins and wires and checked out fine but it would not work, a new clip and harness fixed it right up. I ordered it direct from Caerbont in England....I think it was about $8 but it got my tach working again.
http://www.guess-works.com/Tech/ratio.htm (http://www.guess-works.com/Tech/ratio.htm)
4th with a 3:10 at 6k RPM is Infinity! 152 mph by the numbers!
You'll need to play with your details better but a good guide!