I have a bunch of questions about restoring the main and engine harnesses.

Any material or process to restore flexibility in the wire insulation?

Same for the original outer tubing?

For breaks in wires and large holes in the insulation, I think the best solution (short of running a complete new wire) is to solder-splice the break, and cover it with heat-shrink tubing--yes?

Any good way to seal small holes and cracks in insultation?

When replacing missing or broken spade connectors, crimp only or crimp and solder?

For small cracks and cuts there is brush on electrical tape 3m, Permatex and others make it. there is a company named Starbite the has a clear version. Sometimes I use clear shrink over damaged insulation. I did find one useful trick while looking striped wire to match. Use model paint or spray a little paint in a cup of the stripe color you need and just paint it on yourself.

digi key connectors just like original with your special crimp tool, no solder. I replaced all the tube that covered the wires. Not an easy job but nothing will bring the old plastic back to life. I purchased the loom tube from McMaster Carr. It has printing on it that comes off quick with lacquer thinner.
Solder breaks and extensions then heat shrink tube. It will all be covered by the loom tube. If you don't know exactly how long a piece should be where the end is missing make it way to long and add the connector when back in the car.
I heat shrink connectors that carry current just in case something should bump it.
Have fun.

Warming with a hair dryer or heat gun (be very, very careful) can help re-shape a harness.

Clean jacketing with Prepsol or Klix88. Clean connections with Caig DeOxit and a stainless brush.

Stair step any splices so you don't have a big bulge in the harness.

Use good quality electric tape like 3M Super88. You can put a dab of PVC cement on the end of the wrap to glue the plastic tape

Use the Marine grade heat shrink if you can find it. I soldered quite a few during my conversion 7 years ago and each is covered with the marine grade heat shrink. Still waiting for one to break. The stair stepping comment is a wise one. (IMG:style_emoticons/default/beerchug.gif)

Your intent and motivation is admirable. For the engine bay harnesses, do yourself a favor and keep track of your time and costs for researching all aspects of this project, workmanship requirements, special tooling, circuitry analysis and sourcing specific parts, some of which it is doubtful that you will be able to locate, at least not without buying in bulk quantities with long lead times. When you ultimately realize that you may end up with a spliced, taped together harness with incorrect parts on your classic car, at a cost (if you value your time) of significantly more than purchasing a new harness, consider...please consider...just buying a new replacement.

Candidly this post is in part self serving, but I am also trying to help you in an unself-serving way as your brother in this 914 community for over 20 years. All of this has already been done for you and the end result is available to you for a reasonable price, quickly, with the benefit of skilled and experienced workmanship. Unless you just like the journey and thats cool too - the journey is priceless - total respect for that.

In that regard some free advice, worth only what you paid for it (nothing!)...split corrugated conduit, and its clunky connectors, have no place on our cars. Nor do the red/yellow/blue insulated 'squish on' terminals from the Orange or Blue box stores. These indicate the ultimate DAPO wiring hack job.

Yes you can get new connectors, sleeving materials are available, not exactly like stock, some better , some not so much. What Jeff is getting at is that with a wiring harness, you can be chasing problems that are intermittent on an old harness unless you replace all the wires. They may look good, but unless you take the old sheathing off and replace it you can't tell. This will require most of the connectors to be removed from the wire to re run them back into sheathing. There are multiple "branches" so order of operations is important. Also you do want to make sure you "tie off" the ends at the circuit board side.

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Jeff is being honest that he's biased. I always appreciate that! However, the advice from both Jeff and Mark is priceless even though it is free.

I'm have no $ interest or bias that puts money in my pocket. So many of the posts on this forum are related to wiring that is past it's prime. Insulation that is stiff and craked is just a problem waiting to happen. Spot patches and paint on insulation are temporary fixes at best but somethies it is the cheapest and most expedient thing to do. I completely understand. These cars were never intended to have a 50 year service life.

Personally, I'd love to replace my whole harness if that were feasible but replacment with a 50 year old NOS harness would be equally useless. At a minimum, I'll be buying a new harness for the engine where the heat, solvents, and age have really taken thier toll.

Since I love to stir the pot, I'll post a link from earlier in the year on crimp vs. solder debate.

Link below has a great list of small parts as posted by @bbrock and the whole raging debate of crimp vs. solder complete with links to NASA documents and links to F1 wiring harness workmanship and standard practices.

http://www.914world.com/bbs2/index.php?sho...342568&st=0

Bite the bullet, buy new reproduction and move on if you want your engine to run right. (IMG:style_emoticons/default/biggrin.gif)

I scanned over "engine harness", and totally concur with @JeffBowlsby Unless you've got the materials, tools, and experience to make an engine harness; consider buying one.

On the chassis harness, you don't have the option to get new (at this point anyway) so a really good salvage harness, or saving your original one is usually the only choice. Good used harnesses will always require some repair.

+1 Perry

That's why I jumped on this.
The wires are soft and flexible.
Basically feels new.

Always crimp first & then solder, not the other way around. In other words, don't "tin" the bare wire before crimping because the solder will flow. You really want mechanical contact first (especially in a car). I have a used harness that you may borrow for scavenging. Just cover the shipping costs.

Thanks for all the replies. I do appreciate the wisdom gained from many years.

I am still committed (and maybe naively optimistic) about repairing the main harness. There are some real trouble spots, and more minor problems. Since I am not in a hurry, I am contemplating running complete lengths of new wire where I can trace a problem wire from end to end, since I have to untape and retape much of it anyway.

And I plan to warm up on the alternator harness, even though that is a relative bargain to replace completely.

I need to look at the engine harness more carefully (next on my list). My impression so far is that the wiring and connectors are in pretty good shape. The boots are trash, and the outer housing looks ugly.

A closer look at some of the wires--not very encouraging.

Get a new FI harness

When I restored my main chassis harness, I removed sheething and tape and scrubbed everything down with soap and water. I follow with a couple liberal wipe downs with 303 Protectant. Like Perry said, gentle heat can also help bring back some suppleness. By the time I was done, the old stiff harness as bright and flexible like new. It looked so good that my neighbor who has restored a couple Mustangs asked how much I had to spend on the new harness. It's surprising how much life you can bring back to them.

In addition to refurbishing my main harness, I built a few ignition/alternator harnesses from scratch. I enjoy doing that kind of stuff. However, when I get around to refurbishing my FI, I'm most likely going to buy a new one rather than try to DIY even though it would be a fun challenge. Like Jeff said, chasing down all those connectors would be a big job.