Hi, I just picked up a 87 iroc convertible with the 305TPI engine bad. I have a 93 LT1 engine on the engine stand from my 93. I know my way around LT1's very good. Here is what i have for the transplant so far

93 LT1
Engine Harness
93 ECM

Do i need the underhood fuse block?
Do the 87 ECM come out of the car or stay in the car connected?
How many wires need to be joined and where to?
Which harness will need to be cut?
Will the 305TPI fuel pump be ok?
Will the gauges and lights from the 87 still function?

I have been reading posts for the last 3 days and have been finding mixed results.

 

1. Not necessary, but nice to have
2. Comes out
3. Not that many, only about 5-6 really need to be spliced. Been too long since I've done the swap to remember which ones and where
4. Both. Almost all of the original comes out
5. Yes
6. Yes. Though if you have a cable speedo you'll need to figure out something for the VSS

 

Thank you for the reply, would it be easier with the fuse block or more complicated? how much of the harness from the fuse/relay block should i ask for? So i'm pretty much taking out the 87 ECM harness and ECM and replacing with the 93 ecm and harness... I guess i just have to splice the wires for dash lights/ functions and the ALDL connector and ignition switch.

I am going to be using the 700r4 tranny...does that one have a cable that runs to the speedometer or do i need a dakota digital box to send the speed signal to the dash?

 

i used the LT1 underhood fuse box and altogether spliced about 20 wires to do the swap. 5 or 6 were needed just for power distribution! There are a good number of wires for the guages alone and several wires for the fuel pump. I decided to utilize the 4th gen fuel pump relay and connect it to my 3rd gen fuel pump. Your best bet is to collect as many year-specific accurate wiring diagrams as you can. Shbox.com is the best place to go to get LT1 wiring digrams for all years. Aside from wiring, you will need fuel line adapters. I bought mine from a member on this site named Z28r i c e r and am very happy with them. (I normally wouldn't leave spaces to defeat the text censoring... but come on, it's his user name!!!) Also be sure to keep the engine side "clam shell" motor mounts from your 305. They will bolt right to the LT1 block. Be careful on the passenger side when you mount it. It's possible to mount it upside down which moves it too far forward... ask me how I found that out! Be sure to orient it the same way it is on your 305 and you'll be fine.

 

most of the wires you will be splicing into on your thirdgen will be found at the C100 and C207 connectors. find those diagrams for your 87. the C100 is the bulkhead connector on the driverside firewall. the C207 is under the pass side dash...assuming it's the same as the firebirds.
i found the thirdgen diagrams at austinthridgen.org and used the "LT1 wiring for dummies" thread....that was all i needed.

 

http://www.camaroz28.com/forums/showthread.php?t=474185
The clearest one I have found.It will only get it running of course you will have to find and hook up others.