Is it worth changing complete car wiring harness for new LS3 install

[Tomcuschieri]

Hi everyone I'm doing an LS3 swap on my 71 Camaro. My question is there a benefit to changing out my whole wiring harness for the car? I was looking at the Painless Performance 26-Circuit 1970-73 Direct Fit Camaro Harnesses 20112. How will this interact with the LS wiring harness. I was going to utilize the Holley Terminator X ECU and harness set up. I'm just not sure if I need to do this or not. Thanks for the feed back in advance.

[dhutton]

If your wiring is in good shape then it is not necessary to replace it imho....

Don

[andrewb70]

I recently made a long, detailed post on the Holley support forum. Here is a link:

https://forums.holley.com/showthread.php?47957-Wiring-considerations-for-Holley-EFI-systems

I have been working with Josh from Ridetech to help him wire his second gen Trans Am using everything I listed in the post above.

The only interaction that you will have from the original harness with the Terminator X EFI is a single wire that was originally meant to power the coil. The rest of the underwood wiring will be added in the manner that I posted. The Bussmann power distribution module will take care of fans and ECU. If you follow what I wrote up, you will have a clean EFI installation that will give you years of trouble free service.

I also do Holley EFI tuning.

Andrew

[djorgensen3]

If you do decide to swap it out, avoid the Painless kit and go with American Autowire classic update kit. It will have all the new connectors and such. MCB has the best prices and good support.

[John McIntire]

Awesome post on the Holley forum Andrew. Very informative. It couldn't hurt to have that info posted somewhere on this forum. Any way to do that?

[Tomcuschieri]

Thanks I'll look into it.