i was wondering if any one could help me wire a tach up because i am haveing some problems how to wire it to my ignition switch and headlight ??

My tach has 4 wires :

White - goes to the headlight dimmer switch -- same as other gauges lights

Green - goes to my distributor. Instructions say it goes to the NEGATIVEside of the ignition coil which may be labled TACH, TACH TEST, DEC or ECU

Black - goes to any ground.

Red - goes to battery voltage terminal - hot.

I hope that helps.

Alan Horvath
54 Chevy Pickup

On my Autometer Tach that I just hooked up, I actually wired it to one of the ignition terminals in the fuse block. That way it's not always on. Other than that, I agree with Horvath!

CHEV66JB

That's what I did also -- red wire.

Alan Horvath
<a href="http://AlanHorvath.com/54chevy/" target="_blank">54 Chevy Pickup</a>

same as above for my sun tach II

cyberdyne digital gauge...
purple - switched light source (instrument dimmer)
black - ground
blue (if equipped) memory recall switch
white - coil / tach sender wire on computer
red - switched 12V source (acc)

Most tachos work in the same way, they need a supply and a trigger. Most supply cables are red and black for the 12v supply be careful and check as some manufacturers do use other colors, these go to a good ground (usually the black one)and a 12v ignition supply (hot - live - when ignition on), the other wire is usually green but again can be other colours, this is the trigger wire and on a HEI goes to the tacho connection on the dissy, if on a dissy and coil it goes to the side of the coil the is connected to the dissy (usually maker negative) again quite commonly green. Coils have a permanant supply either dirrect or through a balast resistor this should be the posative side with the negative being the trigger from the dissy.
The negative trigger pulse wire and can also be connected to a ecu tacho pin if used on later injected vehicles.
If a light is incorperated there will be another wire possibly blue for this alone, this is connected to the dash panel lights or rear side lights.
good race tachs also can be equiped with a built in or independant rev limiting sw, this can be on an internal sw where you set a red line needle and it cuts a sw connection provide, this is put in cct with the dissy and negative coil connection and interupts this trigger path when on the red line thus cutting the spark - engine slows - coil re fires below line.