Now wouldn't that be a great bumper sticker - DUI Ignition

I am looking at updating the points setup in my '69 390 and came across their GM HEI style distributors for FE engines. Then I went looking around and found simple electronic trigger points replacement kits for a 1/3 of the money.

Is a Davis Unified Ignition billet distributor worth the investment...or what do you prefer?

 

If you are going to change, go with the DUI distributor....the "kits" are documented garbage....and you can quote me.

With regard to reliability & “e-box replacement kits”. Yes you can hear people state "It runs so much smoother/better than when it had points"........in each case that an individual said that in my presence, they had very little knowledge about points and the ones they were running were- old & tired or inexpensive aftermarket replacement units or the individual (including professional mechanic) was unfamiliar with not just setting the gap to OEM specs, but setting the dwell & initial timing to what the engine likes.

But let’s look at the OEM ignition system from the early 60’s….
Original Coil Voltage: 20,000; by the end of the 60’s 40,000 volt high performance coils were common…..by the 70’s 50,000 & 60,000 volt coils were easily available & is what we have today. Did we really gain all sorts of HP/TQ with all this extra voltage…….no, what we were able to gain was stronger support (if you will excuse my terms here) for higher RPM’s- specifically in the 6,000+ range…..enough to power NASCAR engines in the 8,000 rpm range at 200+ mph!

Points were used in NASCAR up through the late 1970's, running speeds of 200mph+.........Cale Yarborough did lose a race one time because the ignition points broke. In a street application, if you look at the data very closely that is provided by these more common e-box companies, in street applications (where max power-band RPM is around 6000), when the standard dyno deviation is removed (5% standard per every dyno mfg) there is less than 1% improvement in performance.

Further testing by independent aftermarket DIS (direct ignition system) manufacturers verify this through their own testing- there is little gain over an ignition points system until you reach 4000 rpm…then you begin to see a slight sustainment of ignition delivery above what points can deliver but it doesn’t even begin to compare to what a “modern”, real e-based system can & does deliver in a real world street (and race) environment.

I am not promoting this product but their analysis is very demonstrative of actual performance results. link: http://www.compu-tronix.com/MightyMo...risonGraph.pdf
The other item is, in a street vehicle, if you wait to see improvement until 4000+ rpm, the race is over.

Here is a link to a back to back ¼ runs- comparison of points vs a couple of e-box conversions……..no discernible difference PerTronix Track Test

These e-box “conversion kits” have literally the same design limitations as the “conventional points”- because they are essentially using the same delivery system (rotor, cap, wires, etc.) and they are subject to the same inherent design impactors of which there are numerous….including ozone that is produced within the cap…..none of this has by miracle “disappeared” and in fact when compared in true recorded data-frame analysis, the benefit will be gone by 5800 rpm and the loss, although slightly less, parallels that of points. In racing conditions that could very well make a difference, but in a street application, you could literally change brand of fuel and see that level of improvement or degradation.

Additionally, there are companies such as ProComp whose “High-Tech Multiple Discharge Ignition Systems” are nothing more than re-boxed low tech conversion parts purchased in bulk from other companies- mostly Chinese-based. Check out this pic procomp ignition box?? of a “new” ProComp e-ignition system- it’s a glued together GM part stuffed into a pretty aluminum box.

Considering they were sued in 2006 by MSD (and prohibited as part of a settlement from using/distributing any of their parts), I’m not surprised by anything I see with their crap….but this includes much of the e-box aftermarket industry- a lot of PR documents which physics does not play any part!

Very good quality ignition points/condensors are available and when set properly, are very reliable and provide excellent performance. There have been no less than 5 people who I personally knew were going to get e-boxes, then I had them get a good set of points/condenser, a high voltage (40k+) coil, and installed them showing them specifically how to do it......the engines ran smooth and strong. One person did end up buying an e-box, why, because he said he just got tired of not being "cool", after spending $500 for a distributor, etc (he went “Popular” high end), a year later (when he asked me to help him fix something) he admitted, it was a waste of $...it didn't run any better than after we put the points in.

While many state the positives of e-boxes (and there are certainly many positive attributes), there are conditions which reduce an e-boxes effectiveness & reliability....to start with the circuitry and handling (container vessel shipping) of it from China (which is where 90% of the more common/popular e-box company's products originate). Any aspect including temperature control (at 115 degrees F the circuit boards are permanently damaged), static safeguards, moisture can & will cause both detectable and undetectable damage which may not show up until after you have subjected the installed component to real world vibrations, heat, cold, moisture & grease/oil. Yes, all of these damage e-components, but the systems (based upon a variety of factors) are suppose to be prepared to endure these exposures but that is based upon many, many assumptions. Including proper handling & q/a.......given all of the 3rd party involvement in the final product, it is unrealistic (IMHO) to believe that e-boxes have an increased reliability as compared to their mechanical-based counterpart. And in terms of “Dwell Control” I won’t even go into that in detail but I will say, what the “kits” provide is a joke…..you can actually get more control over the dwell by having an understanding of how to set timing versus dwell setting with points than the most popular e-box conversion kits can provide…..which makes for a very smooth running engine- this is not just IMHO, but well known among the "higher quality" aftermarket engineers whose systems reflect this ability to "tune"!

If you need to say I got rid of my points…ok, that’s fine, but if you are really serious about actually upgrading the ignition system then do so……although it has been scrapped by the OEM’s in favor of more advanced, effective systems, the aftermarket DUI units (yes the same as Ford used in the 90’s & developed by Porsche in the 80’s) whose cost is within reach of most buyers and will actually perform as stated.

 

I know ponts can work fine but I don't like the amount of maintence they require. The timing is also not as accurate as electronic styles.

Ignition isn't a problem on these automotive small bore engines. I deal with engines that have an 18" bore and 18" stroke running on natural gas. Switching from the old magnetos to modern electronic ignition is a big improvement. The engines are running at 300 rpm and injecting the gas around 30-45 psi. This results in poor mixing with rich and lean areas in the cylinder. Being able to increase the arc duration time is a big help. Another solution we use is to raise the injection pressure to 500 psi. to improve the mixing.

I'll stay away from those cheap add in kits and use something like the DUI HEI style distributors. I haven't pulled the distributor out of my old '69 390 but I'm expecting the shaft bushings to be worn out. Right now too many things keep getting inthe way of rebuilding that engine...I just need to reduce the dream engine down to a regular rebuild with a cam, then maybe it would happen.

 

"I know ponts can work fine but I don't like the amount of maintence they require"
The current set in my 65 Mustang has about 12,000 miles on them...no adjustments...again, much of the mis-information IMHO on this is directly to the inadequate installation procedures (which are not even referenced in any of the newer- so to speak publication in the past 20 years) and that the "trained" mechanics are no longer asked to show the how-to's anymore.

"The timing is also not as accurate as electronic styles"

If you researched the referenced reports, including the industry test/analysis which was published (and referenced), the "e-conversion kits" are less accurate & adjustable than points....of course with the exception of the HEI, etc units.

The reality question that I would pose is......

If points can power (consistently) a 5,000 lb car to run for 500 miles at 200+ mph (later exceeding the top speed of the Indy cars)....how much effectiveness are we really gaining?

Electronics are sensitive to...
Heat (above 115 degrees F direct exposure, all circuit boards are destroyed)
Cold
Static shock (rubbing your hand across your head produces enough static charge to damage components- aerospace industry has specific training programs on these safe practices)
Moisture (typically transported in static safe packaging filled with GN2- gaseous nitrogen)
Dirt/Grease

I

 

The Hall Effect sensors that I use to rebuild old BMW motorcycle ignition trigger units are capable of withstanding +302 degF. They are very similar to the ones used in the retro fit kits. They were used on air cooled BMW motorcycles from 1981 to 1996 and then used on oil and water cooled BMW motorcycle engines up until last year (I think).

Points usually last about 40K miles with a little bit of adjustment to keep the dwell time correct. Electronic igntion system last longer and don't need any adjustment.

It's easier to carry a spare set of points to put in on the side of a road then to carry a complete electronic distributor.

 

For the 1980's-90's Duraspark ignition systems, the weak point was the TFI module that was screwed to the side of the distributor. In that position, the module has been known to overheat and sustain permanent damage. Replacing it requires a special thin-walled socket of a really odd size (forgot what it was). I've never had problems with mine, but I relocated it to the inner fender just to avoid problems.

 

Stock Ford distributor with Pertronix module. Bullet proof in my years of using them in AZ heat. I stick them in and never look back. Air cooled VW's galore out here and I'd venture to say the majority use Pertronix modules. Talk about heat!

I'd still run points if Pertronix wasn't around. Big dollar distributors and ignitions are a waste of money unless you are blowing out the flame kernel with tons of fuel/boost or racing high rpm's. Dyno the 390 before and after the DUI install. If your current ignition is up to snuff; you won't see any appreciable gain. So much hype out there like garden hose sized ignition wires.