So when I picked up my '87 Iroc the LB9 had been removed due to a giant hole in the block and I decided to replace it with either a 4.8 or a 5.3. Now I have never done an engine swap before, but since I'm not in a hurry, I figured it is something I could handle lol!

Ok, first off, I'm not having an issue with locating the needed parts to do the swap. Where I'm having the problem is what to do with the factory wiring. As in what can stay and what can go.

My plan is to have a completely stock looking Iroc but with modern running gear. So the factory a/c and cooling fans are staying, but the factory gauges are going. The engine is going to be managed by a MSD Atomic LS system which has the provisions for two fans, speed ref & signal, tach (12v square wave signal), fuel pump, and keyed power.

I know that pretty much all of the stuff associated with the tpi, along with the computer, will have to go. But can I use the existing wiring for the fuel pump, tach, oil, volts, temp, etc. with the new gauges?

Any info would help My poor head is spinning thinking about all of this lol!

 

yes it will, however when you see that wiring from the diagrams your going to be in the twilight zone

 

That's where I'm at now. I have a full set of shop and service manuals, including electrical diagnosis. So basically I have all of the pin outs and schematics, but I dont know what exactly I need. When looking at the pin outs for the C100 junction block I know that everything in the small harness (headlights, marker lights, turn signals, etc.) will stay. Where I'm unsure is wires like the purple B4 starting system interlock, light blue E6 choke heater, and brown G7 generator/coolant fan/ choke heater wires.

 

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

 

I followed Pocket's sticky when i did my swap. I removed everything except the power wires going to the starter, oil pressure gauge wire, and coolant temperature gauge wire. My car is an 86 and my wiring for the wipers and A/C are are the same harness with the headlights so i didn't touch that side.