alright, i put an autometer autogage tach in my car(T/A in sig). its a 5 incher, with a shiftlight. i wired it all up, mounted it and everything was cool while testing it down low. so i proceeded with the install, finished it up then took it for a ride.

the problem is, when it starts getting higher up in the RPM range, the aftermarket tach starts getting way off, and reading really high. its close to stock own around idle and like up to 2k, but i had my stock tach at 5k when i was getting on it, looked at the autometer tach and it was around 7500. so what could be the problem? it came off a v6 probe GT, but idk if that mattter. its just a generic tach you can buy from summit/jegs, and i thought would wire right up and work great. any ideas?

 

make sure the wire wasnt cut for a v6 or 4 cyl, im sure that is the problem, moving it from the probe to your lt1 instructions are on there website

 

A tach from a V6 will not work on a V8.

Does it have a 4-6-8 switch on it somewhere maybe?