Any Duraspark experts?

[My427stang]

On my F100, I run a box and distributor out of a 75 F100

As with all Durasparks, it has 4 wires on the main harness to the box, but the other plug has 3 wires instead of the later version with 2

In other words, the plug that normally has white and red (start and run) also has a third blue wire.

I can't find a 3-wire black strain relief box, and research leads me to believe the blue wire isn't needed, but I can't figure out what that blue wire does.

Mine is like the top one in this pic, the replacements are like the bottom one.  Note the top plug in each diagram, both have the white/red, one has the additional blue wire



- Can I replace the box with the standard red/white combo?  The plug is the same, they just eliminate the 3rd tang and show a jumper. Some sites lead me to believe yes, but not clear
- What's everyone's opinion on replacing the box with an MSD?  I have never had any issue with a Durapark and looking for long term reliability

Thanks

[jayb]

Electrically, that blue wire is feeding the voltage at the coil when the engine is running back into the Duraspark box.  Just as a guess, I'd say that some of the boxes require that voltage, and some don't.  If the box doesn't have a provision for the blue wire, it probably doesn't need that voltage signal and it would probably be safe to run without it.  You'd have to try it to see, I guess...

[My427stang]

Makes sense, after you spelled it out.  Might be an internal crossover in the new boxes.  I can buy a cheap one off Rock Auto for 10 bucks, worth the experiment.

I am on the fence with a CD box on this one due to the low RPM peak, but may bite the bullet in the end anyway, we'll see.  Thanks!

[rcodecj]

It also looks like the black and purple wire from the box on the bottom connector is reversed on the later versus early.

[JimNolan]

my427stang,
    This may not be any help to you, I hope it is but when I went to an ignition setup on my 63 galaxie I was running as much as 15 degrees initial advance. Of course cranking the engine left a lot to be desired so I went with the Duraspark II ignition. I can tell you for sure that if you don't hook up your main ignition red wire and just run off the white solenoid wire, it will retard your timing 6 degrees and the engine will run just as long as you keep the starter entergized, once you let off the key the engine dies though. That being said.
   I used the Painless Duraspark II wire harness #30812 from Summit. Bought a Duraspark II coil from Rock Auto ( oil filled, has to be set in upright position ). A Duraspark II control box from NAPA ( $39 ) and a 1974 390 Duraspark Distributor from Napa. I took the distributor apart, welded up the slot in the mechanical advance to .410" (20 degrees ) and threw on some Mr. Gasket recurve springs and Wah-Lah, it worked great.
   Now the reason I'm telling you this is not because I don't think you can read a schematic or know what you need. I'm telling you this because I've got 4 wire connectors that have two wires coming out the other connector etc. I gave up trying to figure out what I needed, every schematic I found was different from the last. I'm an electronic tech that can do boolean algerbra and follow a logic diagram as well as a schematic and I couldn't figure out for the life of me which schematic on the internet I found to wire my system up. I just plugged it all in and it worked. I've run it now for 10K miles in the hottest temps imaginable and I haven't had the first problem with it. Jim

[My427stang]

Thanks Jim

I installed this one in 1986-ish, so its a running system.  The problem is over the years the connectors got brittle and finally fell apart.

I may just replace the ends with Weatherpaks, but we'll see.  Part of me wants a rev limiter with an MSD or equivalent, but this has been dead nuts reliable since install.

I'll make a decision very soon, as my inner fenders and radiator support will be done Wed and I will have no excuses to not fire it over the 4 day weekend.

FWIW, I have it wired just like you described, but that extra blue wire had me concerned as I cannot buy the exact replacement from NAPA

[Carnut427]

The first couple years of Duraspark was a different system. The "best" Ford box to use has a blue wire strain relief holding the wires to the box.

Dan

[My427stang]

Mine is the 75-76 version, it is a little different

I ended up finding a replacement box, it ran too well for too long for me to change anything.  Heck, this box would still be in use if it didn't start crumbling away, and I installed it...used..in the mid to late 80's

If I decide it's not happy on the 445, I will take your advice though.  As I understand there is quite a bit more power from the blue boxes

[ScotiaFE]

The really early ones had a red grommet.
Super rare, but had the highest output.
The blue box is good though.

[drdano]

This is a good topic over on FordMuscle about the differences between the blue and red grommet boxes.  I'm using the red box with my duraspark curved by Faron and Blaster 2 coil, 8mm StreetFire wires.  TFI coil compatibility, on-start timing retard function.  I love it.

http://www.fordmuscleforums.com/galaxie-pages/504320-conversion-electronic-ignition-input-please.html

[65er]

I've had the Duraspark/MSD setup in my Galaxie for I guess about a year and a half/15K miles now with no issues.  I can't remember offhand how it's all wired, but I know I just wired it up per the MSD instructions.  I got a molex connector from Radio Shack and installed it near the distributor so I can plug and unplug as needed.  The molex connectors are easy to install and only plug together one way so there's no fear of hooking anything up backwards.

[My427stang]

I bought a replacement from Rock Auto for 9.95 LOL  Its not a name brand (KEM Electronics) but it fired right up and all the wires match

For that price, I'll probably buy a couple for spares.

With that being said, I wired my original, fired the motor, timing was at 12 BTDC, then swapped to the KEM, timing was stable at 8 BTDC.  So something inside is different.

I adjusted initial and it's doing everything is supposed to.  We'll see how long it lasts.

The motor seems to be a bit snappier than I expected, in the end I may just put an MSD with a rev limiter, but I'll wait until I get the doors and fenders on first LOL

[BruceS]

I've run a MSD 6AL with their Pro-Billet distributor for about 7 years on my SB 66 Fairlane. Dead reliable so far. I put the 6AL box under my front seat to get it out of the engine bay, which was just a personal preference...

[My427stang]

That cheapo KEM is running fine for now, and I can buy a repop Ford Duraspark sticker if I am really bothered by it

No doubt the MSD will do great and adds a rev limiter, but I just couldnt see spending a couple hundred dollars to replace an ignition that was meeting what the truck does.

We'll see though, went from a 8:1 390 that didn't have enough head or spring to rev past 4500, to a 10:1 445, it may decide it want's a little more zap.

Need to get the doors and fenders on it and see how it feels with a load on it at higher RPM