Doug - I like the Ford trigger design and will defend that part of their system for sure. The pulsed signal is very strong and self powered. And I think the seperate controller arrangement is a smart service design as well.

The Ford control module is another story - the Motorcraft versions of later vintage (with the blue strain relief) - seem to be capable of more heat stress cycles than the earlier models. And as someone pointed out - the offshore boxes aren't all that reliable as a replacement. Your 25,000 mile life has been reported by others - and I've melted a couple on company trucks over the past years. The Ford engineer(s) that mounted a whole raft of their controller units right next to the exhaust manifolds of many cars and light trucks - should have had to sit on a few of them for a day or two. How this escaped the reliability people would be a useful story for training purposes. Just shielding them seemed to have made a difference in failure frequency on our old company F-150 trucks of the era.

Heat issues aside, there are drawbacks to the design of the dwell circuitry of the Ford units that limit their usefulness. The chip is set-up with a fixed dwell - 27° - equal to the dwell setting of the old (single) points system. They use a resistor wire in the connection wire from the ignition (1.3 OHMs) and an oil filled coil of 1.0 to 2.0 OHMs primary resistance which by spec should result in 4.9 to 7.9 volts at the coil. In perfect condition - this is also going to result in a pretty anemic spark by modern standards. It's no better than the sparker in my old '62 Falcon.

For a hybrid system - that still fires by induction - I recommend using the GM HEI "four pin" module and remoting it to its own heat sink in a cooler environment. These make use of a Motorola patented chip that varies dwell to control heating of the grounding transistor. This makes them capable of handling 7.5 AMPs of current and 35 volts - the Ford design boxes are not in the same league. Using real GM modules - and keeping them cool - makes all the difference on longevity. They run on full system voltage (13.5+) - no ballast resistor - and the dwell variance allows use of coils with .5 OHMs of primary resistance - this means they are fully saturated for a good deal of the typical RPM range. After "field testing" a couple of systems - I can tell you they work very well. It will rival the performance of a "red box" up to the useful RPM limit of most of our outfits - and is much less expensive.

 
 Steve Metzger       Tucson, Arizona

Doug,

      I can't tell you if the 200 inch six in the same year car had the Duraspark. I can't tell you because it never went bad in 100,000 miles and I never looked at it. I do have to agree with the comment on the HEI units, lost a number of them and learned to carry a spare and tools with me. As far as MSD reliability, I just fried my third (and last) MSD6al in the Red car. So they have problems too. In fact this must be a bad year for electronics since the GILL (English) unit in my Triumph motorcycle went bad as well. Sure wish I could replace THAT with a dura-spark. The factory replacement sells for $760.00!  

Frank/Rebop

Bristol, In ( by Elkhart) 

I had a few go bad but once replaced with a decent quality aftermarket replacement never had any more problems,I usually had them go out when the vehicle had about 75 to 100 thousand miles on it and most likely with a Motorcraft module. I convert all my Fords with points to the Duraspark system and use the parts I get from the donor vehicle and did have a aftermarket module go bad but it was one of those cheap replacements,did have one pick up coil go bad out of all of them I messed with and it would start cold and run all day long as long as it was not turn off but if shut off would have to wait for it to cool down before starting again.

Butchering up everything I can get my hands on in Dayton Ohio

Steve,



I was asking because of your knowledge and expertese about the Duraspark and how to put it on a Y. Please remember the questions I asked which were: "So were they eventually improved? Can you depend on them today?"



My experience with the modules was bad which was the main part of my posting and I put it on "This n That" so that comments wouldn't need to be specific.

Doug T

The Highlands, Louisville, Ky.

Do you guys want a serious discussion? If a fellow has a y-block engine and doesn't have bucks for a new MSD distributor - and wants a street electronic ignition with vacuum advance - please show me the available economic alternatives for an ignition trigger unit? With pricing? Step right up - we're all waiting ....

I'll help....you can use the Ford Duraspark stuff (that fits fairly easily) or a plastic "points replacer". Last time I looked, a lot of the guys on this site are automotive hobbyists - figuring their own system out (or building it) isn't beyond their skill set. When going down that road....I'm in favor of using the common parts that work, and you can get service replacements for on Sunday afternoon. As far as I've seen on my own vehicles - the early version Duraspark II triggers are pretty good. Every one I've seen messed up so far had a worn out distributor shaft bushing - and a resulting mechanical failure of an electrical part (or a broken wire). Very infrequent incidence of either one - doesn't strike me as a big worry.. The 8 blade trigger provides a pretty secure signal - and makes its own power too. Once you have a distributor with a workable, reliable trigger the rest is up to the builder right? How much do you want to spend - things like that have to be dealt with too..

With a reliable trigger - you next select a controller that can handle the power you want to deliver - and a coil that can handle it as well. If you don't like the 35 year old Ford controller design - I don't blame you - but you would be hard put to describe a system design that is more serviceable right?..... The set-up of the Ford system - where the control is external and can be serviced with a simple "plug-in" remote controller unit - beats the GM distributor head mounted (HEI) design hands down for service capability - and it beats the little low power Pertronix points replacer outfits too. The easiest service fix of an unknown electrical fault is a component change ... and I swap one of my adapted GM controllers out in minutes. Let's time that against one of the points replacement outfits shall we?

 
 Steve Metzger       Tucson, Arizona

As a dealer tech I replaced those Duraspark modules during those years regularly. Usually it was about a 10 to 1 ratio to replacing the ignition pickup. Occasionally both. The modules were not holding up; heat and vibration causing the printed circuit to break even being encased in jell. Many times the circuit would separate when hot and not start. Then after cooling down to normal temp the circuit would shrink back into contact and would restart. I always carried a spare module and pickup in the trunk of my cars. I have a Duraspark distributor on my 66 F100 390. I use a MSD6 module. This problem carried on into the next generation TFI modules and E-core coils with EEC IV.

57 Black Tbird 312/auto

Steve,

I was the proud (briefly) owner of a '79 302 V8 Fairmont Eurosport, briefly because the pride did not last long!  The chief problem with this car was that it ate Duraspark modules in about 25000 mi.  The first time it happened was in a McDoo's parking lot in the middle of Pa with 3 kids, wife, and dog on board.  The tach was not vibrating when the engine was turning over which was a clue that the module was F--ked.  There was an auto parts dealer in walking distance and he had one at list price but he wouldn't loan me a nut driver to get the old one off. I just remember being stiffed for the nut driver which I still have and have not used since.  The second time was on the Cape May to Lewes Ferry trying to start the car to get it off the boat before I had to start paying demurrage on ship, not fun!.  It finally did start.  I think that this was a systematic problem with the Duraspark module and I have never wanted to see one again. So were they eventually improved? Can you depend on them today?

Another problem developed with the Ford/Autolite 2100 type carb. It ended up with a porosity between the main well and the float chamber.  So if the car sat overnight it drained the bowl but would start after filling the bowl, if it was shut off for a few minutes it wouldn't put enough gas in the engine to flood it.  But if it sat for about 2 or 3 hours, hot the engine got hopelessly flooded and it would crank and crank without starting. 

I bought the car new special order in the spring of '79 but it was out of warantee when all this started to happen.  The car had some nice features, bucket seats, the Mustang Dash panel, Cruiso on the floor, some styling cues that were unique to it but it was a dog at 130HP.  I think it would be a pretty rare car today but it met it end many years ago.  It had the least milage I ever put on a car when it was traded in.

Doug T

The Highlands, Louisville, Ky.