I've heard Duraspark, Pertronix, and MSD. Can anyone tell me what the difference between the brands are (if there's more that'd be cool too!) and what would be best for dragstripping, daily driver, etc? Thanks
My Duraspark runs great and has been trouble-free for years. Pertronix is easier to install. MSD is the ultimate (and more expensive) and works with any stock Duraspark distributor (or you can get a MSD distributor)...
18,000 trouble free miles with my Duraspark II setup. I feel more comfortable with the Duraspark II setup, considering if any part of it were to stop working, I can get replacement parts at the local auto parts store.
This is like the Holley/Carter arguement... Easy bolt in and go: Pertronix Willing to do a few wires: Duraspark Willing to pay some bux: MSD
Sorry missed this part... Duraspark: Original Ford electronic ignition. Is basically a magnetic trigger ignition inside a distributor housing. It looks like a points distributor, but has a remote mounted 'brain box', about 4"x4" in size. It uses a much more powerful coil and puts more power to the plug. Very durable for the most part. The brain can go out, but my 75 still has the original, so it is reasonably durable. A replacement brain is anywhere from 15 to 50 bux depending on where you get it and the quality of the part. It is 'solid state' electronics. There is also a bonus of having a timing retard built in. Mostly for easy starting, but some here have pointed out it could be beneficial in many other situations if you were to trigger it... such as nitrous. Pertronix: A mysterious little black box that replaces your points and senses the position of the point cam lobes to trigger the coil. About 75 bux... Have no idea how it does what it does. They are reasonably durable too. I have had one on a 4 cyl engine for years. The Pertronix 2, however, has had bad press. It is more delicate and I have heard that there are reliability issues. No experience with that one though. It puts out almost as much power as the Duraspark. Mallory Unilite: Avoid like the plague. Used to work for these folks and the little light sensor is always burning out. It has an optical sensor and light. Then a little 'curtain' hangs under the rotor button. It has 8 little slits cut in the curtain. Every time a slit passes the light, it triggers the coil. VERY FRAGILE! VERY EXPENSIVE TO REPLACE LIGHT MODULE. MSD: Too many to list. Mainly operate under exact same principle as Duraspark, just pretty polished housings for all the dough you spend. You can run an MSD box in place of the Duraspark 'brain' if you choose. The Multiple Spark Discharge box DOES work, but only to just over 3k rpms. Under 3k, it fires the coil 5 times for every plug. After that though, the coil cannot keep up the pace, so it fires once. However MSD claims that the single spark is longer in duration. I don't see it... did they slow the speed of light?
Pertronix really doesn't put out power at all. It is merely a hall effect switch that replaces points and a condenser. It is the only option if you don't want to go through the hassle of replacing your distributor. All are good options, although almost anything MSD is probably more geared for performance than you need, and it costs plenty. The Ford Duraspark system is decent too, but a bit more work than a Pertronix. Pertronix is about 15 minutes and you hardly even get your hands dirty. Hall effect switches have been in service for over 30 years, and have an excellent reliabilty rate. I have run mine for over 7.
The coil is what puts out the power, but Pertronix can only trigger a coil of so many thousand volts while MSD and Duraspark can trigger a coil of much higher output. I forgot the exact numbers, but there is a big difference in coil limits. IIRC, a Pertronix falls in the middle of points and magnetic trigger in it's ability to fire X-amount of voltage coil.
My Pertronix I triggers a Flame Thrower coil that says it is 40,000 volts. More than enough on a 393 that sees 6500 rpm regularily. YMMV...
ratio is right about those unilites. have one in my truck that the previous owner put in. already had to replace the unit once when coming back from a camping trip. i carry a spare lite module now incase it craps again and will most likely be putting a stock 390 dizzy in soon (happen to have one laying around) and putting a pertronix in it. i also had bad luck in my grabber with another brand but they went out of business so no worries there.
Sort of put this combination together over the years and it fires 11.0 :1 compression through 6500 rpm without a hitch. Duraspark II distributor and box. Low resistance cap (I use accel) - coil input button (part that hits the rotor in the middle) on a lot of cheap caps is made of a graphite material that has thousands of ohms resistance. The plug leads are made of aluminum and easily corrode. Stay away. Accel and MSD caps have brass buttons and brass plug leads and seldom need cleaned. Spiral wound solid core plug wires (lowes resistance you can find) - I use MSD wires. I tried straight non wound solid core wires and the magnetic interference generated by them creates burps in the circuitry inside the Duraspark box. Big old ugly yellow 50K volt Accel super coil. Mount the Duraspark box and the coil as far away from the engine and heat as you can practically get them. Heat kills both. Regular old resistor plugs (cheapest ones you can get) no gimmics - just check them and change as needed. I usually use Autolites or Motorcrafts which I think are made by Autolite. Cleaver
so when you change over to a duraspark dist. do you have to switch to a different coil.if so which one. i have the original right now.
What about a Davis Unified Ignition? Based on a Chebby HEI IIRC. I know it is a brand X modified part, but does anyone have any experience with the ones made for Fords?? According to their site, they run at $369.00..not exactly the cheapest thing out there. They claim: The Street/Strip Ford D.U.I. is built with a 50,000 volt coil that allows a whopping .055" plug gap to be run and this will provide a more powerful explosion of the fuel mixture. The Dyna Module is designed with more electronic dwell time producing a hotter spark. No ballast resistor is used. Stock Ford systems, and many aftermarket systems require a ballast resistor which reduces the voltage in the ignition system. The D.U.I. allows FULL voltage into the ignition system, providing a better spark and more power.
You don't HAVE to. I ran my original points coil for a few weeks and it seemed to do alright. I have a Ford TFI coil on it now. and it works great.
A new stock Duraspark coil is cheap at your local auto parts store. I have seen the D.U.I. for $150 at Speedway Motors. I think those are pretty cool...
