This might be helpful to somebody.
http://users3.ev1.net/~bmarr/duraspa...de.htm#credits

 

Now having posted this, I have a question. I'm not a guru and don't pretend to be. I was talking to a guy who specializes in Mustangs and asked him about this upgrade. He said if I already have a Pertronix Ignitor in my distributor (which I have plus an Accel Supercoil) then I've already got what I would get if I did this upgrade. Comments?

 

All these conversions do is remove the points and use an electronic signal to fire the coil. Duraspark uses an amplifier box (kinda like a MSD of sorts) to fire the coil. The Pertronix does not need the amplifier box.

See, how it all works is kinda like a backwards motor(a generator). Take a magnet and wave it next to a coil of wire and it makes a pulse of current. This pulse is then used to fire the coil. Every time the "stator" on the shaft swings past the little coil mounted in dizzy, it pulses a signal. Simple, effective and very stable...unlike points that wear out, move around.

I'm no guru...............but I did stay at a Holiday Inn Express last night........

 

That's makes sense.
Now, when I get my higher compression pistons and 941 cam put in there, should I go to an MSD box?

 

They do help, especially at lower rpms. Not mandatory, but it does give you a rev limiter also. They aren't getting any cheaper.......

BTW, I hope I did not mislead you when I said the Duraspark amplifier box. In this term, it means it amplifies the signal from the dizzy to fire the coil. Not like an MSD that MULITPLIES the signal TO the coil. Kinda confusing, but back when this was first made(in the 70's) the technology was not there to create things like Pertronix that does it all in this little gizmo that fits IN the dizzy. Just want to clarify.

 

So if I have an aftermarket coil that is already pushing more than stock, I wouldn't need to multiply the signal but it wouldn't hurt to have more than one spark or is that what you mean by "multiply"? If that's the case, then a double platinum spark plug would almost do the same thing, you think?

 

I added the DuraSpark dizzy and went with the DuraSpark coil and GM HEI module, doing away with the DuraSpark box... https://www.ford-trucks.com/forums/s...d.php?t=327065 I may also upgrade to the TFI coil next, just becasue I have one in the garage. All this cost about $30. I think you see a benefit for daily driving and use, but really more so when you wind them up in the higher RPM range and demand some heat.

--Mike

 

MSD fires the coil multiple times at low rpms. This helps keep the plugs cleaner, start easier, idle better. If I remember reading the specs right, after 3000 rpm the MSD does nothing different than a plain electronic ignition. There is no physical way to fire a spark plug multiple times at say 6000 rpm. Just not going to happen. Multiple tip plugs only fire at ONE point only. Electricity is always looking for GROUND. It will find the quickest way, period. With 1,2,3,4 electrodes hanging out there, it gives it just more chances to find GROUND(in turn firing the fuel mixture). The plug will not fire on 2,3,4 of those electrodes, ONLY ONE. I know they make it sound like it will on the commercials, but electrically it will not happen. Like I mentioned, it just wants to find the quickest way to ground, and with more than one way to get there, it will work "better, easier" to get there. Hence quicker combustion, etc.

Just for a for instance...for the first few years on my race car(428) I ran a dual point dizzy, stock coil and plain/stock 7mm wires. It ran fine up to 6500 rpm. To this day I still run cheap 7mm wires, but did switch to a Unilite dizzy. It still runs the same time as with the old style stuff, but starts easier/idles better. You'd be surprise how much "overkill" stuff that one can put on a motor that it basically doesn't need. Ok, maybe every little bit helps, but seat of the pants driving around town....not needed. Maybe in Pro stock racing where every .0001 second counts, but not our trucks.

Just giving you something to ponder. Don't just throw a bunch of money at it for the sake of it. Every motor is different. My 428CJ in my pickup runs all stock components in it(no MSD, old dual point dizzy, stock coil, stock wires) and no issues.

 

Freightrain is right, the multi-spark is THE big advantage to the MSD/Mallory, and the rev-limiter just sweetens the pot.

Going to a bigger coil can cause other problems to a base-stock ignition system. Frying capacitors, points, etc, because the "backlash" (or hysteresis) from the coil will cause another spark across the points as they open, overheat the capacitor, etc.

The MSD does get more output out of the SAME coil, PLUS the multi-spark at low-end where our big-cam, high compression motors can really use it.

In my highboy, w/11:1 390, big cam, etc, it made a huge improvement over the Durspark. But then, I was lucky to get 9-11 inches of vacuum at idle, and it loped like a 10-point buck

In my case, the rev-limiter was enough to justify the purchase of an MSD at around $200 at the time... the multi-spark was the icing on the cake.

It all depends... and yes, ditto, the Pertronix is basically the same as a Duraspark setup.

 

I am learning alot today, whew! So for the occasional red light competion, daily driver truck, MSD is overkill. Okay, easy enough. I've still got so much to learn. Anyway, tell me the benefits of the GM HEI set up. My truck will probably never see more than 4000 rpm but I'd like to know that I blast if I wanted to.

 

Comment 1: I wouldn't say it is overkill - the rev limit is nice if your tranny or driveshaft(s) give up no matter what motor you have. You put big bucks into it rebuilding it, why run the risk of breaking a rocker/rocker-shaft or throwing a rod? The multi-spark is nice if you have trouble with cold-starts or idle quality (big cam). In my case, I had both and it helped a LOT but even in my old 360 I would have loved to have better cold-start idle/running.

Comment 2: I would think the higher spark voltage helps, but basically you can get them cheap over-the-counter... Other than that, I see no reason to defile your Ford with a GM HEI

Here's more:

1) You might want a slightly hotter coil - MSD sells one or two and others have them too, and probably work with Duraspark or Pertronix.
2) If you want to get away from points, but not spend multiple $100's, get a Pertronix.
3) If you have a mild-to-wild motor with a lot of money in it, get a rev-limiter.
4) If you have a wild cam, get a multi-spark unit.

For the money, the MSD at $230 w/rev-limiter would make a big difference even on stock motors, especially on cold-starts. I paired mine with a Ford dizzy, with the Duraspark pickup inside. Worked great.

Sorry, I think I'm repeating myself.

artk.

 

Well, I already have an Accel Supercoil (50,000 volts) and a Pertronix Ignitor electronic ignition. My cam will soon be installed, it's the Crane 343941.
So that's all an HEI does? Heat up the spark?

 

Yup... High Energy Ignition - HEI.

You should be good ... the multi-spark would help idle, but doesn't do much else... except cover lean or rich conditions