Happy new year all!

In the middle of a ground-up on a 74. Car is pretty clean but looking at the wiring. Looks clean as well. No chafing etc. Replacing the relays and cleaning the board etc.

Is wiring ever too old? Don't want to go through all this only to have to tear it all out with the engine in the way etc.

Car was a summer car in VT so no exposure to salt air etc.

Thanks in advance!

Unfortunately, nobody is currently making a harness for a ‘74 and all the nos ones floating around are early 70-71

From your description it sounds like yours is still in good shape.

I would definitely unwrap, clean and check all the wires to make sure you have no breaks, wear marks and then re-wrap it before installing it. Look for added on wiring and connectors thatch be removed and the harness repaired. Stereo/alarm installers of the 70's and beyond are notorious for ruining harnesses.

Rarely is a wiring harness beyond repair unless it has been dunked in water (especially salt water) for an extended period of time. The water wicks way up into the insulation by capillary action and destroys it with corrosion.

If the insulation is pliable and intact, the copper within will be OK.

Brittle insulation will crack and cause all sorts of gremlins. Repair or replace.

Wire insulation can be tested with a Megger if in doubt about its integrity. However, at 12v, automotive wiring isn't at high risk of arcing due to insulation breakdown.

Bad sections of harness can be repaired by splicing with proper gauge wire and proper termination techniques.

The important harnesses (alternator, ignition, and Fuel Injection) are available from Jeff Bowlsby.

https://bowlsby.net/914/WiringHarnesses/

Kroon makes a harness for the /6 and IIRC RD is starting to make harnesses but they are not cheap because they're not cheap to make.

You might want to contact Gerard at Kroon he is currently making a chassis harness for my 1973 2.0L.
He will be using mine as a prototype for future harnesses so I would think if you approach him he might be looking for more examples.

Funny. I sent mine to him a couple years ago and then after a year he told me it wasn't worth it and sent it back. I guess times have changed.

In Germany MS-Bordnetze makes a complete harness for the 914

https://www.msbordnetze.de/porsche-914.html

@Boothy

I just went through a similar project this last summer, where-in I took an adapted harness from a 75 - 3.6 and transplanted it into my 70'. Granted, you don't need to remove the harness so the whole process is pretty straight forward.

As other members mentioned, check for any splicing and rubbing and that the wires are flexible. This is a great time to un-tape certain sections, check underneath, clean and re-wrap. Though I eventually went a different route and applied 'safety sheathing', 914rubber.com sells a great tape that will leave the harness looking like new.

Yes it's here -
https://914rubber.com/wiring-harness-tape-1#

Also note that it's 180' roll. Correct width - 4 roll for a complete car

We also make the tab covers 13' needed for a complete car

Great stuff, photo of the tape here. Anything from 914Rubber is

Click to view attachment

Great!

Thanks all for the help. I appreciate it.

I'll go through it all and do as suggested.

Best!

This website looks interesting but I have not seen any actual product, close-up photos or customer reviews.

Curious to know exactly which harnesses are offered and provided? For example, for the 914/4 there are at least 3 different versions of 1.7L FI harnesses, 3 versions of 2.0L FI harnesses, 3 versions of Ignition harnesses, and 8 versions of chassis harnesses. They are not interchangeable, each one is unique.

Nothing is offered for the 1.8L cars.

Are they all new parts are or some parts reused originals?

The very first part I bought for my 914-6 was an NOS wiring harness, still in the factory sealed bag and box from Porsche. I believe I paid $1,200. When it arrived I felt like God had reached his hand out and delivered the absolutely perfect harness.

If you have a questionable harness, the Germany MS-Bordnetze harness which if my math is corrects about $2,800 is actually not all that bad. Think of the hours you might save chasing wiring Gremlins or replacing parts that short and cause damage.

Finally, anything @JeffBowlsby makes and sells is going to be perfect- that is just how he is. So whatever harnesses he offers for your car, you would be foolish not to replace with his new ones.

I remember that was a great score for you. I bet a used six harness is worth that much.
When someone here pointed out a nos early four harness on German eBay for $850, I jumped on it. The wires are soft and flexible. Feels like new.