For reference I have an 87 GT with the stock 2.8 and Getrag.

When I bought the car the loom on the engine harness was a bit melty. I bought a used replacement harness from a forum member and have been going through it making sure it is in good shape. With that out of the way, it is time to wrap it back up. My plan is to use DEI Firesleeve 3000 (500F continuous, 2000F peak) where the original harness had aluminum tape.

As for the rest of the harness, I know polyethelene convoluted split loom (200F) isn't adequate. Using nylon (300F) should be good. However, I think I would prefer to use self-wrapping braided split loom from Pegasus Auto Racing (https://www.pegasusautoracing.com/productselection.asp?Product=4013) which is rated to 257F. Does anybody know if 257F would be adequate for engine harness loom?

Thanks, Dave

Here is what I used for my engine swap -

Harness Tape

I would highly recommend this stuff. It is very easy to work with, has even higher temperature resistance, and still looks like new 2 years later.

Regardless of temperature ratings, successful cleanup involves crafty routing. Just because something CAN take the heat, doesn't mean it HAS to. Thoughtfully placed zip ties will ensure that your finished product doesn't get damaged. I wasted money on my first attempt at wire looming. My second effort held up great, mostly because I paid more attention to trouble spots for heat (primarily exhaust heat) and zip tied the harness the farthest away I possibly could. That being said, I LOVE summit's plastic braid, which is a sort of knockoff of painless performance's. The price is a steal and it looks even better than factory jobs of even modern vehicles.
Just my .02

quote Originally posted by Fiervette: Here is what I used for my engine swap - Harness Tape I would highly recommend this stuff. It is very easy to work with, has even higher temperature resistance, and still looks like new 2 years later.

x2 - this is what you'll find underhood on Audis, BMWs, and Mercedes. It's great. Tesa tape comes in two flavors - fuzzy stuff for inside the cabin and less fuzzy stuff for underhood. It's friction tape, designed to prevent wiring from being abraded from rubbing on things. FWIW, when I redid the wiring harness on my Falcon I used something like that split-loom braided wrap you linked to (same stuff, different brand). It's fine. But, after discovering a source for Tesa I used it when I redid the wiring on my XR4Ti. Much better result and I can pretty much guarantee it'll last longer. I've dismantled 15 year old Audis and the Tesa holds up wonderfully.

The wrap typically isn't there to protect the wire from heat, although that fire sleeve is designed for exactly that purpose. Somewhere around here I read a comment from a knowledgeable person (maybe phonedawg?) that suggested the insulation on '80s GM products is not highly rated (vs. modern engine bay wiring) and as such I'd imagine you'll want to mimic the factory arrangement - use heat reflective tape or sleeve where the factory did, and friction tape where they didn't. Otherwise you'll probably end up with your exhaust manifold baking something.

Also, as viperine mentioned, it's still critical to properly secure wire to prevent it from wearing from flex or being baked from contact or proximity. All wiring should be appropriately wrapped and fully secured, leaving adequate slack when moving from chassis to engine.