Not sure if this is the right spot for this..but what is the basic wiring needed just for a carburetor? I think I saw a post that stated all the wiring on the passenger side can be eliminated...but I don't know if I belive that.
thanks for any help.

 

The right spot for this, is the Search Box.

There are 20+ Years of Threads on these Forums.
Plenty of which have covered, what you are looking to do.

 

Your car is an 87 TPI,..... so:

Remove the ECM from under the dash
Unplug the ECM
Pull the ECM harness into the fender well
Pull the harness from the fender well to the engine bay
Disconnect the ECM harness from everything in the engine bay.
Put the harness and ECM in a box.

The only wire you will "lose" is the oil pressure sending unit wire. On TPI this wire ran thru the ECM harness.
Rewire the oil pressure sending unit wire.

** You will also need to add a "switched power" wire for an electric choke - if your new carb has one.

** 86-87 Firebird will loose ground to the VSS buffer when ECM harness is removed,... Splice a new ground wire to buffer.

** EDIT: removing ECM harness means you will remove auto tranny TCC lock-up; an aftermarket lock-up kit is recomended.

Done.

 

I would suggest leaving the harness in tact. You will NEED some wires from the interior to the exterior (ie for oil pressure and torque converter lockup as mentioned above). And, you may WANT some as well later down the road. It's very convenient to have an almost unlimited source of interior to exterior wires available for free, without having to poke yet another hole through firewall somewhere. The pass side harness doesn't need touched at all under the dash inside, and when all those sensors and such are unplugged under the hood, the entire harness is easily wrapped and tucked up into the passenger fender behind the strut tower - unseen yet available. All you have to do is trace a wire by color from under the dash to engine bay and verify with ohm meter.

Some examples of how those wires are handy?
* Manual cabin switch to turn on your cooling fan(s) - many aftermarket fan controllers have provisions for a such and it's nice in summer to be able to turn on your fans whenever YOU want.
* Since I went carb and no longer have cruise control, I wired my cruise control ON/OFF switch to lock/unlock my torque converter - I was already used to turning cruise control on when I hit the highway and turning it off before I come to a stop so controlling my TCC lockup is second nature.
* External auxiliary lighting - maybe undercar lights or the KITT light or whatever you desire.
* I'd been having years of starter wire trouble that I could never trace down - so recently I swapped out my cig lighter (I don't smoke) for a push start button, and I used one of those little harness wires with a relay under the hood to direct battery power directly to starter solenoid when relay is "activated" by the push button. I wired push button in cabin to a "hot-in-run" source, so the key still has to be turned on (and also the security function activated with chip in key).

You get the point - since it's easily tucked away there's many more reasons to keep it than to remove it!

 

What about having to ground a wire or two from what is unplugged at the ECM from the dash side (C207? and ?) - can't remember what those 2 were called. I thought there was an instrument cluster ground there that will need to be ground now to body or a bracket or something?

 

C207 is highly dependant on the year so always be sure to review your year-matching C207 schematic to ensure that any discrepancies are accounted for.

From 82-87 there is very little ever needed to modify after removing the ECM harness from the car. My previous post describes the TPI oil pressure wire ( TPI specific ) and the Firebird VSS ground ( 86-87 Firebird with electric Speedo specific),..... but as I write this I recall another thing; Back-up light wiring in Stick cars ( Tranny Specific )

I don't agree that it's better to tuck it under the fender-well and would rather remove it and just re-run the 1 or 2 wires that some cars will need. The 82-88 cars use a power junction block on the drivers side kick panel area that almost always has plenty of unused ports to get hot-power and switched-power from when needed for additional or 'add on' equipment. It's harder to deal with C207 on 88+ cars because the ECM harness is PART OF the Engine harness,..... but 87 and earlier cars use an independant harness and IMO I'd rather remove it entirely and repair/replace the couple wires that are still needed. The dash side of C207 will be hanging and unused under the pass side of the dash and you can always 'tap' into those wires if you need to, or so desire.

Click here to get a detailed listing of the C207 connector for just about all the Thirdgens cars.

https://berlinetta.info/C207.htm

 

My point wasn't about tapping into power within the cabin, all the 3rd gen cars that I know of have plenty of power distribution access inside.

Nor was my point to have access to unused underdash wiring in the cabin, might as well hack out the in-cabin passenger harness half if you're gonna hack out the under hood half.

My point was that - leaving entire harness intact provide you a ton of CLEAN wiring connections already established BETWEEN inside cabin and outside cabin. Without drilling firewall, without creating your own wiring nightmare that is not documented, without creating or leaving holes for mice, ants, bees, and other creatures that think living in a 3rd gen is cool!

My 92 car was a TBI automatic, and literally nothing from passenger side harness was needed or used for a basic carb swap. But I have since greatly appreciated all the "inside-to-outside" wiring options I've used over the years from leaving that harness in tact. And I thought I'd share that insight.

I sure wish all cars came with an extra 10 or 20 "free-to-use" cabin to under-hood wires that were clean factory installs!

 

My message was in response to 3rdgenzroc,........... He has an 86 and I explained the reason I feel the way I do about the ECM harnesses on 82-87 cars that get converted from FI-to-Carb.