I have done some searches and found that lots of you are trying to put aftermarket tachs in these third gen camaros. I didn't find alot of answers on my searches thru the archive, but, I was able to get thru it. SO, I've decided to post this quick
HOWTO INSTALL AN AFTERMARKET TACH IN A 1987 thirdGen in the hopes it will help some of you.
1) Disconnect battery
2) Remove Vanity plate over distributor
3) Find the external coil, it should have 2 connectors on it.
4) Remove BOTH connectors, don't worry they are keyed and only go on 1 way. (you have to pull a retainer to remove the clip)
5) Find the GRAY connector with the pink wire and the white wire
6) Clip the white wire. somewhere in the middle.
7) Reconnect the coil connectors BOTH OF THEM.
8) Reconnect the battery and start the car. You will notice that the old crusty stock tach NO LONGER WORKS BUT THE CAR RUNS.
9) If you have removed the airconditioning vents in the center dash, install the tach (mine is an Autometer Monster Tach with shift light). Run the wires down thru the dash to the firewall, find a hole up around the master brake cylinder.
10) Hook the RED WIRE to the IGN plug in the fuse panel, it will need a male connector on the end to plug it in.
11) Hook the Black wire to the ground (i used the bolt at the far left under side of the dash with a nice extra washer)
12) Run the green wire thru the firewall and up to the COIL. Be sure and protect it well (i used some 1/4 inch rubber tube to ensure it didn't rub on the firewall.)
13) Strip and attach this green wire to the STUB OF THE WHITE WIRE YOU CLIPPED IN STEP #6 ABOVE)
14) IF you have headlight / dash lights you may want to hook up the backlight by using the WHITE WIRE FROM THE TACH. (it may be powered by the RED WIRE as an option).
Get in the car and turn the igniton part of the way, DO NOT START THE CAR JUST YET.....
SEE IF THE TACH RESETS, if it does, you are OK. (RESET MEANS GOING TO ZERO). IF it doesn't, you want to STOP and double check steps 1-14 to be sure you did them right. If it reset,
Then you are free to start it up and take a spin around the block.
ENJOY, A TACH THAT ACTUALLY WORKS, instead of a stock one that is 500-1000 RPM OFF. Mine was WILDLY INACCURATE.
I can send you some pics of the install (or point you to my website if you need more details).
So, there it is, i did it and i contributed to the net knowledge so others can do it.
Oh yeah, there's a good link here
which has some pictures which might help you if you need.
Good luck, and enjoy.
87 IROC Z/28; 305 TPI, 5 Speed. SCCA - class ESP