[64speed]

I originally wanted to run all M&H repro harnesses but the cost for the whole car is unreal. It's not off the table as an option but I have been looking more at the aftermarket kits like American autowire and painless wiring. I want to use all my original switches which it doesn't look like you can do with some of these kits. Which kit is the best most comprehensive kit out there that won't leave me scratching my head for three months?

[HWYSTR455]

Unless you are ready to do customization, those types of kits are not for you. And if you want it to look good, you have to be fairly good with customization.

Almost all the kits serve multiple years, and you have to pick and choose the connectors, etc and install the ones that fit your app. I am in the middle of an AWW install, it's a custom install, and on just the dash harness, I have like 40 hours in it, and probably have another 20 hours to go.

There are alternatives to M&H, but most are competitively priced, so there's no real gain/savings.

Dash harnesses are the most expensive, but are usually the ones that are the most hacked up. You can remove it, lay it on a table, and replace what areas are damaged, then re-wrap. It still won't be as clean as a replacement one, but you will save money.

It's much easier to just pull a dash harness out of the box, and replace the existing one. All the ends/connectors are pretty much a fall-in-place hook up.

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[64speed]

Thanks. That's what I figured. This car is rapidly reaching the price of the GDP of Brazil LOL

[Peter Serio]

There are basically 2 major players in the auto reproduction wiring harness biz. American Auto wire and M&H. The both make good products and all of the Pontiac specialty parts places stock from one or the other. AAW is an east coat company and M&H is located on the west coast in case you decide to deal direct.

I bought a complete dash and engine harness for my '63 Lemans from AAW. It was well made and all of the wire colors matched the GM schematic from my shop manual. It is in my car now and I am very happy with it.

In the case of my car they needed a few of the parts (the plug-in ends) from my old harness which I sent them. For your year car I think they can supply you with a brand new ready-made harness; exact to the original so all your switches plug right together.

[Geoff]

I agree with post #2. Mate has just bought a 66 GTO that the PO owner had bought a AAW complete wiring harness for....... & attempted to rewire. Many wire colours are different from original & the instructions leave much to be desired....

[HWYSTR455]

My memory isn't as good as it used to be, so I am documenting my install. Not a small effort, and not really that much fun either!

To further complicate matters, I'm also doing EFI, and am customizing that harness as well. Uhg.

The crimpers alone can add a considerable expense. I also have a large assortment of connectors (weatherpack, metripack 150, 280, Deutsch, etc), seals, pins, retainers, you name it. It all adds up, but in the end, it will look and function great. Any leftovers can be used on other projects too.

I went through trying to find just fuse boxes, wanted ATO fuse box, but the manufacturers only sell in quantity, and none of the harness manufacturers will sell just the box. Capitalist pigs. If I would have been able to do that, I would have made one from scratch.

Good wire isn't cheap either, and it's best to use the appropriate wire for appropriate jobs. For the most part, TXL is what should be used. As an example, 16ga is about $3 per foot, depending on quantity.

When you look at it that way, the $600 or so for a dash harness isn't such a bad deal, and really, one can wonder how they do it that cheap.

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[Lemans64]

If your not real good with electrical stuff I would stick to M&H or something similar. It's plug and play, no guessing as to where or why. It may be a little more expensive than the build your own generic harness but it will install in way less time and there won't be test fits while laying inside down under the dash, nor will you have to tape the harness, then take apart and retape, LOL.

[JLMounce]

I have M&H stuff in my car. I discussed with them at length the same thing, going with either modified stock harnesses or going customed harness. In the end, it was just better to buy the reproduction harnesses. The only thing I have that needs any type of customization is the FiTech and that's easily handled through the stock replacement harnesses.

So while the expense is there, it's definitely your best bet.

[64speed]

Thanks guys. I called M&H and told them what I was doing and what I wanted to accomplish and everything all in ride and everything is around 1200 so basically I'm paying another 500 bucks to avoid a major headache. I can live with that.

[64speed]

I bought the M&H harnesses and they look pretty straight forward so I am glad I did. I have one question though. I did not want to hack up or splice a new harness so I bought the harness that had been modified for HEI and internal regulated alternator. For the fuel injection accessories I bought a painless wiring 7 circuit add on box that adds 3 keyed and 4 always hot junctions. I plan to run the HEI wire to it to power the keyed circuits and connect the hot circuits straight to the battery. Does that sound like the right way to do it?

[64speed]

Anyone?

[gassman_67]

I have all M&H harnesses, I got them to fabricate the engine harness with a HEI setup. I'm going to install Holley Sniper EFI, Holley dual sync and a MSD 6AL digital. The holley kit comes pre wired for a fuel pump (with relay) I will also use the 2 electric fan outputs, I just plan on wiring the 2 ground trigger relays close to the fans/battery. No additional fuse box needed.

[Tempest]

I purchased the entire wiring system for my 64 Lemans from M&H and am very disappointed. The plug at the firewall for both the engine wiring harness and the headlight wiring harness would not plug together. the terminals were so cheap that they started breaking. The dash harness was about 5 inches too short to hook up to the ribbon harness easily, and the "customer service" was awful.

The entire system is what I would expect from a 'Made in China' product.

M&H was sure eager to promise me the world to secure the order, but after that, it was, and still is, a nightmare.


I don't know where to tell you to go to get a quality wiring harness, , but I would seriously consider an alternative to M&H.

Good Luck

[lugnutx2]

I used Lectric Limited harnesses on my corvette, looked factory and fit well.

[64speed]

The M&H harnesses look exactly like the harnesses I took out other than one being clean and one being dirty and all jacked up and spliced. I always thought M&H were THE authority on factory wiring harnesses. I guess I’ll find out in about a year when I’m ready to start putting some power to some things.

[64speed]

Just to make sure I test fit my engine harness and front light harness to my dash harness by plugging them in on the bench and had no trouble getting the to plug together

[Chris65LeMans]

I just finished a re-wiring with an M&H under dash harness. Everything is color coded - I went and labeled everything first - print outs of the wiring diagrams came in handy.

For the ‘65, I needed to buy an add - on harness for my rally gauges. M&H said that ‘65’s don’t need a different under dash harness for HEI - but that ‘64s do.

Very happy with M&H and their customer service. I was able to figure it out on my own, but would have been able to call them for babysitting if needed.

[HWYSTR455]

Originally Posted by 64speed

I bought the M&H harnesses and they look pretty straight forward so I am glad I did. I have one question though. I did not want to hack up or splice a new harness so I bought the harness that had been modified for HEI and internal regulated alternator. For the fuel injection accessories I bought a painless wiring 7 circuit add on box that adds 3 keyed and 4 always hot junctions. I plan to run the HEI wire to it to power the keyed circuits and connect the hot circuits straight to the battery. Does that sound like the right way to do it?

Actually, you would want to connect the power feed for the add on to the common post on the starter, or move the starter relay function (or common post) to an external ford sol as done in the hot start fix. If you put the battery in between the power source (ALT) and the load, the load will pull from the batt first. If that makes sense.

Most EFI companies state that the ECU MUST be plugged directly to the battery, which always puzzled the heck out of me, but I guess they are taking into account all factory wiring scenarios. Sometimes that will be one of the first things they ask when you call support, so however you want to handle that is up to you. I just suck it up and run it right to the batt, but I'm on the wall this time around when I finish my current wiring project.

I strongly suggest running deep cycle batteries when adding 'loads' to your factory electrical system. I generically use/recommend the Optima Yellow tops, which are only about $50 or so more than a good lead/acid battery.

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[tom s]

I have used M&H on at least 3 diff cars without one issue?Tom

[HWYSTR455]

I too have heard spotty reviews from M&H lately, though I personally have always had good luck with them. I do recall once when I asked about upgrades, the pre-sales person got impatient with me and short.

I'm doing an AAW classic upgrade harness for my current project. It's similar to the Painless type harnesses/kits, and all I can say it is far from painless. If I were to do it again, I would only order the dash harness, use OE for the remaining, and modify them. Main reason I went with an aftermarket harness is for the ATO fuse box, an item you can't buy only one of, the manufacturer requires a minimum purchase for like 100 or more.

I should do a separate thread on that to give others insight, from my experience using the AAW harness. It would save a lot of people from some of the hurdles and pitfalls I experienced.

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