So before I'm ridiculed here ive been through several 700r4s and tpi in both my 305 that i bent rods on and a 350 that i lacked ability to get right and just wasnt happy with it. therefore along came the carb intake and carb, an msd 6als, and an hei. I tapped the hei into a coil wire from the tpi harness. the entire tpi harness is still in there. but my goodness is it a mess of unneeded wiring. Im also running a th350 trans with monza tail hosing allowing the electronic speedo.

From what i can understand i need to retain the ecm to control fans and fuel pump which i could work around but also speedo which i dont have an effective solution for yet.

how do i thin the unneeded connecters from the harness? chopping stuff out really isnt in my being but im not seeing a way around this. i thought of possibly using a same year TBI harness with my 7730 ecm but those use a buffer box and such which doesnt really work out the same. im also to understand that unpinning connections cleanly at the pass side bulkhead doesnt work well.

-leave the mess?
-remove the harness and hope to find answers for everything lacking ecm?
-do i just unloom it all, roll it up and shove it in the fender? feels hackish
-or do i just start cutting? Really hate this option.

after hours of searching im just not sure ive found good advice in most threads, or they are talking different years/efi's which appears to differ largely.

What has everyone else done?

 

I hate cutting wires. I folded my wires back and taped them to the harness by the firewall. I had the engine out when I did this. With the engine in you can't see the wires. So with engine still in it might be challenging. Fold them back where you can and make it look as nice as possible. When you lift the hood no one is looking at the wires...unless it's a mess. lol. I kept the ecm. I didn't do anything to the speedo or fuel pump and they both work fine. As far as the fans, I don't know how to retrain/relearn the ecm. My fans would come on when they shouldn't and won't come on when they should so I installed a switch and indicator light for each fan so that it doesn't interfere with the original system just in case some day it works properly. I also added a idle stop solenoid connected to the a/c compressor so when you come to a stop with a/c on the engine doesn't die.

 

Sounds like you are in the same boat as I am.
I am doing a TPI to Carb swap on a Vette. And you think yours is bad you should see mine at least you have room to do stuff.
This pile of mine has zero.

I am thinking of going the unloom route after i figure out everything i want or need to keep and just remove it from the loom and reloom the whole harness.
When doing a swap there is so much that I have found does not need to be there is nuts.

Also from my understanding the Fuel pump relay does not run through the ECM. I could have that wrong though.
And there are easier ways to trigger the fans to come on and different temps by changing the temp switch and wiring into the fan relays

 

i too have debated this. speedo is really my only hiccup.