Just came it from the garage cant get the tach to work yet here's what I did no computer car no tach filter just 1 wire from the cowl hook up at d6 a white wire from there to the msd box an it still doesn't work car is a 87 iroc with carb. Thanks.

 

You may need a MSD tach filter. This pic is how I wired mine it may help

 

I have everything a msd dist coil an box 6al . according to msd book I shouldn't need nothing. lost

 

Are you using the Stock Tachometer or an After-market tach? Does the tach stay low, read high, or some where in-between?

Going off of what Midias said, and considering our charging systems the information here should be usefull (hopefully).