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Inverted wires MSD 8869

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DoctorC
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Location: Valencia (LA), CA

Inverted wires MSD 8869

Post #1 by DoctorC » Wed Jul 31, 2019 12:52 pm

Hi All,
To hook up my MSD-6AL to my Duraspark ii distributor I bought the 8869 harness as recommended by the manual. However, the harness I got has the wires inverted. Now, i paid for a harness so I want the darn thing to work as it should. So I wont be splicing the wires and calling it a day. I called MSD (holley) and they're gonna replace it.

This post is for those who get screwed in the future.

Here's the wiring diagram per the manual:
MSD-6al wiring.jpg

MSD box green (-) <--> Distributor violet (-)
MSD box violet (+) <--> Distributor orange (+)

Here's my setup using a new harness MSD-8869
20190730_215729.jpg

Top is coming from MSD box
Middle is harness
My finger is holding the distributor side of the hookup

Note that the wiring goes Green (-) -> Violet -> Orange (+)

So tonight I'll cut and splice the wires on top and then see if my vacuum advance finally works. When the new harness gets here I'll swap it out.
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1967 Cherry Red Mustang
Weber 32/36,
MSD 6AL+MSD Coil,
Duraspark 2 dizzy

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bubba22349
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Re: Inverted wires MSD 8869

Post #2 by bubba22349 » Wed Jul 31, 2019 4:54 pm

:hmmm: Except the wiring isn't going to do anything for your vacuum advance. So before you start cutting and splaceing the wires know that the vacuum advance is only controlled by the engines vacuum Conections and nothing to do with the any of electronic control box or the Distribitors pick up wiring. Good luck :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

DoctorC
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Location: Valencia (LA), CA

Re: Inverted wires MSD 8869

Post #3 by DoctorC » Wed Jul 31, 2019 5:48 pm

This is true, but not totally correct. From what I've read/understand, the inversion of the polarity adds advance since the trigger will be on the wrong side of the magnetic pickup. So when the vacuum advance gets hooked up the advance becomes excessive quickly, hence the engine trying to shake it's way out of the engine bay.

Could be all bogus, it's the internet after all. I'll splice tonight. I'm getting a new harness in the mail anyway. So if I'm wrong, it's gonna be re-corrected shortly.
1967 Cherry Red Mustang
Weber 32/36,
MSD 6AL+MSD Coil,
Duraspark 2 dizzy

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bubba22349
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Re: Inverted wires MSD 8869

Post #4 by bubba22349 » Wed Jul 31, 2019 6:11 pm

:hmmm: So how is the polarity inverted?

By the above MSD's supplied wiring diagram!

The (DS II) Distribitors Orange wire is Positive + and the Violet wire is Negative -.

On the MSD box the Violet wire is Positive + and the Green wire is Negative-.

So therefore the MSD Violet (+ wire) connects to the Distribitors Orange (+ wire) next the MSD Green (- wire) connects to the Distribitors Violet (- wire). Which is how it's already hooked up now. I think you might be looking at the wire colors rather the were the wires go on the diagram. Good luck :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

DoctorC
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Re: Inverted wires MSD 8869

Post #5 by DoctorC » Wed Jul 31, 2019 7:34 pm

Hmm, I don't see what you see. I see my wires connected Green (-) -> Violet -> Orange (+).
Of course assuming wires in a straight line to each other are connected.

The Squared connector is the MSD box side
The round connector is the Distributor side

the square side of the harness is taking the Green (-) from the box and connecting to Violet
Then that same Violet is connected on the round side to Orange (+) on the distributor.

That's negative to positive.
1967 Cherry Red Mustang
Weber 32/36,
MSD 6AL+MSD Coil,
Duraspark 2 dizzy

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bubba22349
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Re: Inverted wires MSD 8869

Post #6 by bubba22349 » Wed Jul 31, 2019 8:31 pm

Yes your absolutely right! :shock: :rolflmao: I finally can see it clearly now, they reversed the plug connections on Distribitor end of the 8869 wire harness. Most likely since the wire colors in the 8869 harness are Orange and Violet like on Distribitor plug end they should have been matched up to the same factory Ford wire colors and on the MSD square plug they would be correct as they are now. Good luck :thump: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

DoctorC
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Location: Valencia (LA), CA

Re: Inverted wires MSD 8869

Post #7 by DoctorC » Thu Aug 01, 2019 12:13 am

Success!!!

So I cut the wires on the square plug side since it was easier. Spliced them together.
--------------------------
So first, the theory:
2010-12-11_001845_duraspark_stator.gif

As the center gear rotates, the magnetic pickup senses the passing of a tooth and triggers the MSD box. I had everything working because a trigger is a trigger and everything is relative. BUT if you fire off the wrong edge, you have a "built in" advance that is not showing up on your timing light, because it's triggered off the MSD Box! This is why the engine goes bonkers when the vacuum advance is plugged in. It advances MASSIVELY an idling engine. This also explains why I keep getting detonation.
-------------------------

Now, of course the engine wont start anymore. This is to be expected since I have the timing dialed in with the previous setup. With the wires inverted I'm essentially triggering off the following edge and not the leading edge of the magnetic pickup. So I should trigger when the signal starts, not when it ends.

Now to get it running again I had to advance a ton compared to previous dialed in spot. I rotated the distributor about 15° advance. It started, but rough. Then i used the timing light to dial it to 14°advance. It purred! Then for the moment of truth i plugged in the ported vac advance off the Weber. Increase in idle, still purring!! Then i dialed in the recommended 17° advance no vacuum and tightened down the distributor.

I was able to dial the idle screw way back, about a turn and a half. I think this also explains why I'm so rich. Now i have it idling happily at 650 in drive and about 900 in park.

My advance is
17° @ 670 rpm
27° @ 950 rpm with vacuum plugged in

So, in summary, wsa111 is awesome and called it correct. The damn wiring was backwards!

Now, I'm a happy camper.
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1967 Cherry Red Mustang
Weber 32/36,
MSD 6AL+MSD Coil,
Duraspark 2 dizzy

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Re: Inverted wires MSD 8869

Post #8 by xctasy » Thu Aug 01, 2019 5:22 am

Wsa111 is awesome. Duraspark II had a color change to the wiring in 1979 from some if the other kinds.Replacements are whitebix, and differ, as well ad having point blank mistakes in assembly line processes.

No one understands the 5 to 10 degree advance that Ford put into the Blue and Yellow and Brown DS II/ DS III. MSD does the same thing. Without all those SOL V null knobs like youd find on a theodolite...Ford had five of them, with three to control advance on certain versions of the 1979 and 80 Mustang and Capris.
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XEC Ltd ICBE's Inter Continental Ballistic Engines-
FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
X-Flow Engine Components Ltd http://www.xecltd.info/?rd=10

drag-200stang
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Re: Inverted wires MSD 8869

Post #9 by drag-200stang » Thu Aug 01, 2019 9:52 am

Being color blind can be good, but not when you are making wiring harnesses.
66 Mustang Coupe
200 turbo w/lenco 4-spd
stock adj. rockers, stock timing set, ARP studs
best 1/4 mile ET 9.85/best mph 139 on 8 lbs progressing to 15 lbs boost
Went 9's when 10's was fast.

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wsa111
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Re: Inverted wires MSD 8869

Post #10 by wsa111 » Thu Aug 01, 2019 12:43 pm

DoctorC wrote:Success!!!

So I cut the wires on the square plug side since it was easier. Spliced them together.
--------------------------
So first, the theory:
2010-12-11_001845_duraspark_stator.gif
Then i used the timing light to dial it to 14°advance. It purred! Then for the moment of truth i plugged in the ported vac advance off the Weber. Increase in idle, still purring!! Then i dialed in the recommended 17° advance no vacuum and tightened down the distributor.

I was able to dial the idle screw way back, about a turn and a half. I think this also explains why I'm so rich. Now i have it idling happily at 650 in drive and about 900 in park.

My advance is
17° @ 670 rpm
27° @ 950 rpm with vacuum plugged in

So, in summary, wsa111 is awesome and called it correct. The damn wiring was backwards!

Now, I'm a happy camper.

Good news. In my log book i show your vacuum advance if plugged into full manifold vacuum should have added 14 degrees. The other advance i sent you had only 8 degrees.
Whatever it runs super now. Bill
67 mustang,C-4, with mod. 80 hd, custom 500 cfm carb with annular boosters, hooker headers, dual exh.-X pipe, flowmaster mufflers, DSII dist. MSD-6al & MSD-Blaster 8252 Coil. Engine 205" .030" over with offset ground crank & 1.65 roller rockers. 9.5 comp., Isky 262 cam.
2003 Ford Lightning daily driver. Recurving Distributors. billythedistributorman@live.com
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DoctorC
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Location: Valencia (LA), CA

Re: Inverted wires MSD 8869

Post #11 by DoctorC » Mon Aug 12, 2019 11:38 pm

So, to wrap this up, I got the replacement part in the mail this week (thanks MSD!) and hooked it up. I checked before and it's wired correctly =)

And that's one problem solved!!!
1967 Cherry Red Mustang
Weber 32/36,
MSD 6AL+MSD Coil,
Duraspark 2 dizzy

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