you might want to check if the pin on the balancer is still there. without the pin, your tach won't work. mine was broken by the oil pan bolt. someone strip the thread on the oil pan so they put a nut on top of it. i had to make a new pin out of a cut-off bolt.

http://pg.photos.yahoo.com/ph/mazzy_1234/detail?.dir=4519&.dnm=6695.jpg&.src=ph