M&H front lighting wiring harness w/ alt conversion

[montyrobison]

Hello all,

I've installed an M&H front lighting wiring harness w/ alternator conversion on my 72 K20 (# 38929). There's an "L" shaped metal bracket about 5" back from the end of the alternator connections. Does anyone know where this bracket is supposed to attach / mount? Thanks for your help and suggestions.

[ChevLoRay]

It mounts to one of the bolts that go through the alternator, to keep the harness from getting into something that you don't want it to.

Just find the bolt that is closest to where that bracket is located and that's where it will best work.

[montyrobison]

Hi ChevLoRay,

Thanks for your reply. I'm not sure why, but there isn't a thru-bolt anywhere near where this bracket would reach. Do you have a picture of one of these harnesses w/ the bracket mounted? Thanks again for your reply.

Monty Robison

[Classic Heartbeat]

That bracket is supposed to be mounted to the top left water pump bolt. (Right side as you face it.) This bolt normaly has a hex head and a stud beond that. The bracket bolts to that stud. WES

[Classic Heartbeat]

Here is a picture of one mounted. I circled the bracket. WES

[huero]

How do you guys like you M&H wiring harness and how much did it cost?
I used them on another project and was very happy.

[LUV2XCLR8]

Mine fits perfectly, had OE connectors, and works flawlessly

[vectorit]

I had terrible luck with M&H products! Spent days trying to figure out why things were not working correctly, found out that the plug to my rear harness under the dash was pinned out incorrectly. That and the ignition switch was pinned out incorrectly as well, explaning why I couldn't turn the trunk on from the key.
M&H is only about 40 or 50 miles from me, so I took my old harness and the new harness they built to show them. They were very apologetic, and repinned everything for me while I waited.
Getting the harness back in, I still had issues and they worked with me over the phone testing every circuit. I still have issues, but it looks like it's all ground related.
Being that M&H worked with me in such detail, spending hours over the phone with me testing every single circuit. I have to hand it to them that they sorta redeemed themselves to me, so I would go back to them if I had another wiring need.

On a side note, I purchased this stuff from OC Truck&Car shop. When I called them to complain, all they did was tell me to call M&H and take it up with them! I said I didn't want to, and I want an exchange. They refused, and just told me to take it up with M&H. Talk about customer service...

[montyrobison]

WES,

Thanks for your reply and the photo. I'm a little confused though. The bracket and portion of the harness in your picture appear to go on up and accross between the intake and the valve cover. The alternator portion of the harness I have has 2 plastic push-in connectors taped into the harness that snap into 1 hole just below the headlight bucket and also to 1 in the lower center protion of the left inner wheel well. Am I routing this harness wrong? It isn't long enough to take the route you show in the Picture. Please advise if possible. Thanks!

Monty

['68OrangeSunshine]

I got an M&H front engine harness back in 2001 for my '71 Jimmy --V8 350,manual,dual headlights,ext volt reg. Worked fine. Fit perfect. Cured a floating ground problem. Was just like factory harness but 30-something years younger and flexible. It wasn't cheap. I got it from Brothers or LMC... Can't remember.
Harness had a tag signed by the guy who built it. I never needed recourse to customer service.

Monty: Do you have a short water pump or the long water pump? The delcotron [alternator] is up high on the driver's side with the short water pump configuration. On the later ['69 or '70] V8s with the long water pump, the alternator was on the passenger side and low. The wiring guys need to know which way your truck is rigged.
Even though my GMC is a '71, for whatever reason [PO's backyard modification?] the 350 was set up like a '68 vintage, with the short water pump.

[paintpyro]

M and H is 10 minutes from my house. I've walked in and ordered in their office. Always been cool guys to deal with

[Steven B]

Mine fit perfect. With HEI and internal alt setup.

[Sport/Truck]

Originally Posted by Classic Heartbeat

Here is a picture of one mounted. I circled the bracket. WES

Originally Posted by montyrobison

WES,

Thanks for your reply and the photo. I'm a little confused though. The bracket and portion of the harness in your picture appear to go on up and accross between the intake and the valve cover. The alternator portion of the harness I have has 2 plastic push-in connectors taped into the harness that snap into 1 hole just below the headlight bucket and also to 1 in the lower center protion of the left inner wheel well. Am I routing this harness wrong? It isn't long enough to take the route you show in the Picture. Please advise if possible. Thanks!

Monty

That's doesn't appear to be the light wiring harness pictured, looks like the engine harness to me. The bracket he shows is for the water temp. sending unit wire- mounted in it's correct spot.
Unfortunately I have sent my forward light harness back to M&H for headlight relay upgrade, so I have no pictures to show.....
s/t

[Classic Heartbeat]

Sorry for the confusion, I do not know what I was thinking. The wire in my picture is the temprature sending unit wire. ChevLoRay was right. It goes to a bolt on the back of the alternator, so that the wires are not just hanging by their terminals. WES

[montyrobison]

To all,

Thanks for all of your comments. To 68orangesunshine - My alternator is mounted up high on the drivers side. I still can't find a bolt / location where this bracket should attach. Could it be the style of alternator? Any ideas out there on this? Thanks again!

Monty Robison

[vectorit]

Here is how mine is attached.

[ChevLoRay]

The pic above is right. It is just one of the bolts that hold the alternator together. Removing one of them to install the bracket is not going to wreck your alternator. Just be sure to reinstall it.

As an aside, not having that bracket and having it secured is what lead me to needing the harness......when the positive lead to the alternator, from the battery, got next to my header and shorted out. Not a good thing. It's very difficult to pull a glowing 10-guage wire apart with your bare hands.....and it slow to heal....besides hurting like....well, you what it felt like, right?

['68OrangeSunshine]

Originally Posted by montyrobison

To all,

Thanks for all of your comments. To 68orangesunshine - My alternator is mounted up high on the drivers side. I still can't find a bolt / location where this bracket should attach. Could it be the style of alternator? Any ideas out there on this? Thanks again!

Monty Robison

Monty:
OK, you have the older type, short water pump style.
All Delcotrons of this vintage hook up the same.
[If you or a PO "upgraded" to a one-wire alternator, then the hook up may be different...]
There are 4 wires in 3 connections,1) a Red 12 Ga that is bolted to the Positive terminal, (called "BAT" in the manual), 2) a dual connector with a Blue 16 (Relay Terminal) and a White 16 ("F" Terminal) that plugs into the back of the Delcotron, and finally 3) a Black ("GRD") 16 that bolts to the negative ground terminal. The end of the angled metal bracket should go thru a 1/2" slot right next to the Negative terminal and the bracket is bolted thru the hole to the Delcotron by the neg stud that comes off the back of the alternator. The bracket makes for a better ground.

Vectorit has it all wrong. He has the ground bracket secured to one of the case bolts. It's supposed to go to the Negative Terminal. He's 120* out.

[vectorit]

If someone has a picture of the "correct" way to mount that bracket I would love to see it! If I am wrong, then I stand corrected. Which may totally be the case, since I did not have this bracket on the original set up.

['68OrangeSunshine]

I'm better at old electrical systems than this modern computer crap. I'll try to shoot some pix with my new digital cam and post them, but when I tried to send some JPEG pix over email last year my earthlink dial-up couldn't swallow it. So no promises.

[montyrobison]

To all,

I'm going to try and attach some pictures of my alternator. Hopefully this will unlock the mystery of where the harness bracket is supposed to mount. I'll look forward to any and all suggestions. Thanks!

Monty Robison

[montyrobison]

Here's one more picture showing the connectors and the bracket. Thanks for all of your help and suggestions.

Monty Robison

['68OrangeSunshine]

I see the problem, Monty. You don't have the usual alternator for a '67-'72. That may be an internal regulator Delcotron ['73-'87]. The tip off is the flat connctor for the "F" and Relay terminals. On an external regulator alternator, the connector is square and the F and Relay terminals are side-by-side, not inline. Also the case has no 1/16"x1/2 slot adjacent to the GRD terminal for the grounding bracket. No wonder you guys are having trouble.
Although you might try fitting the ground bracket hole over the GRD terminal stud and see if there is not a slot within its radius -- outboard, about 1 or 2 O' Clock..
I tried to shoot pix of both my alternators, one on a 292 L6 and one on a V8 350, but my cheap Samsung digital camera won't work, even after I sent it back for service.

[montyrobison]

68OrangeSunshine,

Thanks for your reply. I knew there had to be something strange going on.

However, as you can see from the harness connector picture, this M & H harness was built specifically for a conversion to an internally regulated alternator. I've talked to tech support at M & H, but all they tell me is that the harness is built exactly like the original, including the bracket, with the exception of the wiring changes to accomodate an internally regulated alternator. They don't have any idea where the bracket is supposed to mount.

I'll have a closer look and see if I can't come up with some way to mount it. I suppose pulling the rear half of the alternator housing off and drilling / tapping a 10-32 or 10-24 hole would be too risky, but we'll see. Thanks again and if you come up with any more ideas please let me know. Thanks again!

Monty Robison

[ChevLoRay]

Before doing that, what is the possibility of getting a longer bolt, same thread/pitch and using a spacer to enable you in installing it to one of the existing bolts? It may be that cutting off a portion of the clamp is possible, too. Clearly, to me, the difference in the way the alternator assembles is the reason the clamp does not work as intended in the original configuration. A little modification of what you have (the clamp) is better (to me) than re-configuring the alternator. If you do that, and you have to replace that alternator, you'll have it to do again. Just modify the clamp and make it work with what you have and you'll be good to go with replacement units.