I'm swapping from a 92 RS 305 TBI with AT to a carbed 350 with the same transmission. How much wiring would I have to remove / change to get it running.

 

It would be easier to swap the intakes over as well so you can keep everything. . .

You would not need the ECM, Distibuter would also need to be replaced with a mechanical style. So lots of modifications would need to take place to convert. Some wiring would need to be modified and most of of the harness would not be needed. Remember the torque converter is also controlled by the ECM so you would need a mechanical style there to (vacuum kick down).

 

I am assuming you will no longer be concerned about passing emissions for it would no longer pass the visual. Engines and emissions can be changed but must be upgraded to newer system if converting. So TBI can be changed to TPI as long as all emission equip is upgraded as well. Down grading from TBI to carb and it will no longer pass emissions.

 

I have the distributor I need, it's a coil-in-cap type, so beside the connectors the wires remain the same. The problem I'm running into is that some of the other systems, fuel pump relay, ignition switch, connect to the ECM. I know that not all of them are power, so if i took the ECM out completley, what other wires would I have to tape off, disconnect, reconnect elsewhere to get the system running?

 

Mech fuel pump. If so your are golden. Don't need to change any wires. You can take out a lot though.

 

Is the dizzy a vacuum advance? If not it will not advance the timing based on RPM's. Hopefully you have a block you can run a mechanical F/P off of. There are 2 different styles based on the block off plate. One has a hole behind it for the mechanical F/P actuator rod to go into the other does not. If memory serves me correctly the way to tell is if it has 4 you should be good, if only 3 you will need a low pressure pump for the carb runs on 4 to 4.5 PSI instead of 50 PSI.

 

If I was to valve off the fuel pressure and put a gauge on the other side of the line between a T joint where the fuel return goes back to the tank, couldn't I just adjust until the gauge reads acceptable levels? Then the only thing I'd need would be a wiring circuit that could work without the ECM.

 

You can just keep it TBI if you swap the intake to your 350, you'd just need a little bit bigger injectors but you could run them on the stock 305 injectors as long as you don't go off

 

You need:

carb
vac advanced dist
RETURN-style fuel press regulator (like a Mallory 4309)
TV cable geometry corrector for your carb (brand specific)
method to lock the torque converter.

Wires - everything from pass side harness can be removed - but I wouldn't remove any of them, just get the wires bundled, and tuck in the fenderwell - I have mine like this 5+ years now, and I'm always using the wires for other thiongs (like TC lockup switch, manual fan switches, foglights, etc.).

A few of these pass side wires run from pass side to driver side (like the fuel pump relay activate wire) - just pull them out of the loom so they can be bundled with the rest of pass side wires.

NEVER cut any wire you don't have to - 90% of folks cut wires first, thenm end up resplicing them back later - just cover your @ss and tuck them away for now.


www thirdgen.com/carbswap has some info

 

https://www.thirdgen.org/forums/ltx-...p-3rd-gen.html

 

Thanks for the help, that last link helps. I'll post some pics of my project and keep a log of the work done and the modifications.

 

I have a couple questions about the wiring under the dash.

I'm looking to go as basic as possible, the bare minimum needed to run the car. The only things I need are the radio and AC, everything else can go, besides of course the airbag system and delco anti-theft box.

I've noticed lots of extra boxes where wires connect under the dash, and I was looking for a good description of each of these.

I've removed the computer as I do not need it with the carburetor set-up.

Given this as much so far, how do I wire the ignition switch to run without the computer?

 

I don't know if I would mess with under the dash. I have read a lot of threads, and that seems to be the general consenses.

 

I'm just interested in removing any wires I don't need after removing the computer. I know it's good to keep them in case, but I'm going with the most basic setup possible with keeping the AC, radio, pass key,and airbags as auxiliary systems. There's a ton of wires under there and I know I can get rid of at least some of them, or just the ones I don't need.

 

When you say under dash, do you mean the ones that are where you removed your ECM or the runs that run through your dash. The problem you will run into is that many things will have a comman poer or ground somewhere, so if you cut a wire that you think is coneected to one thing, it may also be connected to another. Best thing to do is follow things you are not using from start to finish and remove them that way, and fix the areas that are commans