Technical Ford duraspark ignition wiring

I hesitated to get into aftermarket EI boxes and my experiences because even the dura is too new for
HAMB. However, I have dealt with the MSD and those have the following issues in my experience.
1. They cannot be tested, except "replace with known good unit and retest". Ugh
2. The tech line always wants the box mounted near the battery, direct and only tap fed, constantly whines about any electrical interference and using a charger and ***umes NO liability even if you follow this explicitly.
3. When I had access to a 'scope, they did provide good spark, but not super great, and the noise problems sometimes reared up with tachs and timing lights. In all, more than is needed for the street and not reliable enough. Heck, a magneto is a lot more reliable.
All of this applies to other brand EI boxes to varying degrees. I think GM got it right with the HEI, but as said, it's ugly. Parts availability, tuning and such make it reliable, easy to install and easy to fix.
My choice for a SBF would be a stock dist. and carry a spare to swap out. Use quality ignition parts and tune it for the car. This ***umes you aren't trying to get max RPM or forced air (turbo or blown), in other words typical street use. The animals out there on drag week are not "street" in this.

Mallory had a good name decades back. For me, they burned any good faith when Super Shops was selling those dual point non-vacuum cheapos that had worse dwell variation out of the box than 100K+ stock stuff. I know they were building cheap bling for the price point SS wanted. The fact they did lost me as a customer.

 

The best answer I think I have determined is , GM module and heat sink on Duraspark , not one issue

 

I worked on the duraspark systems since the were introduced. The early and subsequent duraspark I units were terrible. I started with Ford in 1973 and saw Mera problems and cars coming in on the hook. Ford finally got their act together when they introduced Duraspark I I in the late 70s. I have modernized older Ford products using the module, coil, distributor and wiring. They are as to recognize because the strain relief on the module is blue in color and most of the part nunbers begin with a D7 or D8 part number (77 or 78). The bone yard parts are disappearing, but some still are out there. Wire it up using a 1978 wiring diagram and it should provide you reliable service for years to come. I don't use aftermarket parts, only genuine Ford when I do a conversion. There are several different strain relief colors used, but only the blue one is reliable. The strain relief is the plastic where the wires go into the module. The very early 70's units worked well, the Ford got a brighter idea and gave the entire system one, count 'em ONE ground and it would fail and there you were, waiting for a tow truck. They finally found their cheapened up mistake and introduced Duraspark II. Hopen this info helps.

 

how do I wire this thing ??

it’s pouring rain today so no work for today unless the rain stops
I’m a bit confused
Here’s the instructions that came with the ignition box

nothing with the distributor .




what I think is correct is

big black wire out of IG box to ch***is ground
Big red wire out of IG box to battery positive

out of the 4 pin connector

black to negative on coil
Yellow to positive on coil
Red to ignition switched power
Green is not used

from the distributor
Brown to ground
Green to negative on coil
Red to the ballast resistor and the S terminal on starter solenoid


Is this correct ?

instructions are about as clear as mud.

what I don’t get is , if nothing is connected from the distributor to the box who does it know when to fire ?

 

I’ve got a MSD 6al-2 that needs fixing also.

 

Lower right of pic is the distributor plug. Use 2 of the 3 prongs as stated.

 

This is what I got out of the box and out of the distributor

 

I've ran these on a couple of cars and they were dead-nuts reliable; one of them went over 100K miles without missing a beat. MSDs reputation got damaged by some clever Chinese 6AL counterfeits sold by various shady vendors. But I'll grant that no matter whose electronic ignition you buy, the possibility of failure is always present. Not even NASA or the military manage zero failures....

I'm no fan of the Mallory's as every light-shutter ignition I've tried (including theirs) suffered LED failure at some point. None of the OEMs use them, that should tell you something...

 

Any better?

 

So the green from the distributor goes to the green on the IG box . Looking at the first diagram you posted @Johnny Gee That would make sence to me as now the distributor has a “trigger” from the box.


And as far as led ignition , they were fairly popular by the oems in the 90’s and early ‘00’s but fell out of favour .


This was a good deal for the entire set up .so I ain’t complaining……. Yet .

 

Yep!

 

What are we Yep’in ?

is my wiring correct with the green from the IG box going to the green on the distributor ?

 

No, I was approving the diagram that shows NOT using a light shutter trigger. Magnetic Hall-effect triggers have proved to be more reliable. I've seen too many Unilite failures to trust 'em... which is why you probably got a deal for it.

 

I s****ped those Dura spark boxes in favor of Chrysler boxes, with Fords Dura spark dist. Simple 4 wire hook up, most will run on 12 volts, (no ballast). Just have to watch the polarity on the pick up coil. I like the Orange box but have run Chrome and Gold boxes on the street.

 

I had DUI make me an ignition by sending a new GM 250 HEI. I machined the mount off and made my own clamp for my GMC 302 6. They did not offer any 6 cylinder ignition at the time. It has never failed and continues to perform flawless. I run it at a pretty high voltage at their advice and it been back once in 15 years to be checked. When something works you keep it.

 

At the risk of sounding like an adverti*****t, I really like the MSD boxes. They have features that the 'under the cap' conversions just can't offer.

One, they boost the voltage to the coil primary to about 460 volts. This ensures that you'll get every last bit of performance out of whatever coil your using. If you want a 'stealth' system with the OEM coil, this will give you performance with the stock look. I've used Ford 'yellow top' coils with no issues. You can use most any coil as long as the primary resistance is at or above about .6 Ohm.
Two, they have a current-limiting circuit to prevent coil overheating. This eliminates the need for a dwell control function and/or a ballast resistor. It starts out at about .7 of an amp up to 1000 RPM and adds another .7 amp for every 1000 RPM increase going up.
Three, the Multiple Spark Discharge feature. It takes a finite amount of time to 'charge' the coil to produce a spark (about 5 milliseconds), at slower engine speeds it will fire the plug multiple times. Once you reach about 3000 RPM, the time interval will be short enough to only fire the plug once. This noticeably improves starting and idle quality (particularly with a big cam) and reduces plug fouling considerably if not outright eliminating it.
I believe these also have an 'auto-off' feature, disconnecting power if the motor isn't turning. No worries about burning up something if you leave the key on for an extended time.

Most of the bigger players in the aftermarket ignition business offer these boxes, even Pertronix. But most don't offer quite the same combination of features; some have other features but require additional bits or dedicated coils. You'll have to wade through the features/requirements list to decide which one works for you...

 

Can anyone confirm how to wire this **** up ?



Here’s a book about me for inspiration

 

Well thanks for the vote of confidence!! Lol

I dunno I’m gonna try it , got called into work today , GM plant in Oshawa had some issues , triple time pay and a rainy day made my decision for me .

it’s stopped raining , but it’s muggy as all heck , meh see how I feel in a bit …….

 

So it's now 2025. Was there any resolve to this Uni Lite Issue?

 

Since the good old duraspark problems have been brought up again it my turn to rant. My daily summer driver thunderbird I bought in 85 had no ignition problems up until 2019 when the pickup took a **** replaced the distributor with a Davis put the car away last fall for winter fired it up it ran like **** then no spark put a new pickup in ran like **** found a borg-warner nos pickup not much better my point is the duraspark was once a good ignition but now with Chinese **** parts or aging in the box parts there unreliable. I had enough with duraspark and in the process of installing a ready to run distributor.

 

351 is a taller deck height and different size hex oil pump drive . Just sayin

 

Well ended up selling the merc for the 56 Chevy

but yes I got her running .

my wiring was sound .

issue was when I dropped the distributor in , no matter what I tried the rotor would not line up at 12 o’clock as per the ford manual , but at 6 . Ok 6 is now #1. Some how I went clock wise when I put the wires on , tried to start it , nothing , nada , not a fart or sputter .
After looking at it for what seemed to be an eternity I saw my stupidity , re did the wires correctly and she ran as smooth as a gravy sandwich .
But she’s now down the road to the next owner and not my problem anymore !