Tach question

since ive had my 91 Z28 (about 2 1/2 years)the Tach stays all the way to the top it can go at times when you forst crank it up it goes down and then right back to burieded at the top what could be wrong with it ???

have you done any mods to the ignition system? i know when i put my MSD ignition module in it messed with the tach a lot, they sell an adaptor that fixes this problem but I just went with an external tach

ive been having the same prob with my nine-one...so i cant really tell ya...im thinking about just getting a new tach

have you done any mods to the ignition system? i know when i put my MSD ignition module in it messed with the tach a lot, they sell an adaptor that fixes this problem but I just went with an external tach
jayman350 ,no no mods done as of yet to the ignition system