blue87z28

i got a question would it be easier to swap a lt1 or ls1 into a 3rd gen just to take the harness out of the 4th gen and put it in the 3rd gen or is it less work to do it the way the sticky says to do it just a question

respectirocz

physically speaking the lt1 will fit easier, because you can reuse your stock crossmember, with some modification

blue87z28

na i am just talking wiring making it fit aint a problem if i were gonna do it it would be a lt1 but i am just talking wiring

dhirocz

LT1 fits better with less work, you just have to do some dimpling to the crossmember if you use Fbody accessories. Vette accesories dont require mods.

If u get a wiring harness and plan on using the GM stuff, you better also get the engine compartment harness that goes into the bulkhead connector, that has the fuse and relay block for the fans, etc... or you will need to custom make a harness or buy one.

blue87z28

na what i am talking about is finding a wrecked 4th gen and taking every wire that envolves the motor and just puting it into my car the 3rd gen but tucking everything away basikly like just swaping motors in a 4th gen sorry to cuz so much fuss i was just wondering

FirebatLT1

I think you can get away with modifing the crossmember for a ls1 swap too. I've done the LT1 swap in a thirdgen. I dont know if putting a LT1 in a 4th gen LS1 car or a SBC in a 4th gen would be more/less difficult.

But I do know that its a lot easier to work on a LT1 in a thirdgen because my brother has a 4th gen LT1. I got more room between the front of the engine and the radiator and I have a Lt1 radiator and LT1 dual fans. The windshield doesn't hang over 1/3 of the engine. I think I might have more room on the sides of the engine too. Plus, its just plain cool to have a LT1 in a thirdgen.

formul8

You only need to notch the crossmember on an LS1 thirdgen when keeping the A/C. Otherwise, it drops right in.


www.thirdgentech.com

slimdawson

Lol. Did you guys not read his post? He is asking whether or not to remove the complete 4th gen harness. Not how easy the engine fits.

Btw, Idk. Just figured I would help you get your point across.

formul8

Well...As far as wiring goes, I cannot see why the LS1 would be any harder to wire up than a LT1. The harnesses follow the same routes, there are about the same amount of sensors.

blue87z28

thanx for the help OK I AM TALKING ABOUT TAKING THE HARNESS OUT OF THE 4TH GEN AND PUTING IT INTO THE 3RD GEN GETTING RID OF THE 3RD GEN HARNESS ALL TOGETHER

FirebatLT1

I really didn't modify the engine wire harness too much. The underhood harness, I slimed up quite a bit, not using the 4th gen headlight, abs, crusie control, airbag stuff. The interior harness took me a while to trim down. I have about 15-20 or so wires coming through one hole in the firewall(all for the LT1 pcm), I splice into the thirdgen fusebox inside the car and use the 4th gen underhood fuse box.

You can spend a lot of time making the wiring look nicer. I know one guy on thirdgen.org relocated the pcm to inside of the car and that involved extending 70+ wires 4 feet.

I redid my wiring once or twice already to trim it down some because I had too much wire underneath the dash. And I'm thinking about trimming it down again.

The important thing when you do any wiring/splicing inside the car is to use solder and heatshrink to make sure you have a good solid connections.

Wiring does take a little work but there isn't many wires to splice to get the LT1 to run. Modifying the harnesses and figuring out what wires do what is what takes the most time.

I recommend getting the donor's car's entire wiring harness and then trimming it down, removing stuff you don't need. You might be able to put the entire harness in but certain things are probably different. The lock switches, window switches, hatch release, horn, electrical circuits themselves, electrical connectors, etc., etc, are different electrically or physically in a thirdgen compared to a 4th gen. It would be a ton more work to swap entire harnesses and then try to make everything else work. And a lot more splicing/wiring would be involved.

dhirocz

Well you could do that. I considered it on my thirdgen but realize there is alot involved. You would have to swap alot more than just a harness. You would have to remove EVERYTHING from the thirdgen that plugs into wiring. Pull the dash, remove everything. I would do a dash swap at this point. Install all your airbags, swap the steering column, lay out the wiring. Put in your sensors and relays as best you could and install the dash. Lay the wiring in the engine compartment and hook up your horn, the lights, etc...extending wires where necessary. Run the wires to the fuel pump and to the rear of the car for brake lights, etc. Swap light sockets where you need to (if you need to).

I would think the doors would be the hardest part. You would have to reroute the wires for the door switches to the center console.

I dont see why would couldnt do it, but it would take alot of work. I wanted to do it when swapping over the the LT1 in my '86, but I didnt have a chassis harness.

You could do that or use the LT1 harness and the engine compartment harness, the LT1 harness and wire in your own circuit for the extra relays, or use a custom harness.

Dropping in the LS1 isnt any more tedious than the LT1, but you can at least use your thirdgen exhaust, factory motor mounts, trans mount, etc...the LS1 requires new motor mounts, new custom exhaust, wiring, fuel system modifications, etc...

FirebatLT1

Unless you go with 4th gen door panels.

dhirocz

Hey, I like the way you think!

Zepher

replacing the cars wiring is not worth the trouble. just mod the LT1 or LS1 engine bay harness to run the motor and send sensor data to the stock gauges and that is it.

Now, if you had an LT1 car, like my brothers 96 Trans Am, and wanted to put an LS1 into it, like he is doing, you can swap the ENTIRE wiring on the car to make it completely plug and play. That is what we are doing. Every inch of wire in the car is now from a 98. the dash wires took the longest time to swap over.