Keep DUI Distributor or buy DSII?

When I first started my motor rebuild, I spent a lot of time on the CI site, reading and re-reading every article. From that information, it seemed that the DUI was the best choice, so I bought one. However, I've read some posts on this forum and it seems that members do not look highly at the DUI. I understand that most (if not all) need to be recurved because DUI doesn't do it like they claim.

So, my question is:

Do I keep the DUI and send it in to be recurved? Can I get by, at least initially, without recurving it? Am I setting myself up for failure if I keep it?

Am I better off sending it back and buying a DSII with MSD? With the amount of money into this project I need to get this right.

Sorry, that's more like 4 questions.

@6ponies,

Like you, I was convinced by what I read - including in the Falcon Six handbook - that the DUI offered improved performance, so I picked one up for my highly modified 250 build.

The need to recurve your distributor is based on your engine configuration. There are a lot of variables involved, but my 250 started and idled best at 20 degrees initial timing, so I needed to limit the mechanical advance to less than the default amount to avoid using too much total timing. wsa111 (Bill) could tell you what you might need as far as a custom curve if you give him as much information as possible about your build.

My experience has been that the DUI runs well when it runs, but seems to suffer from component failure too frequently for my taste. You might be able to minimize the impact of this if you order a full set of replacement parts (module, coil and magnetic pickup) directly from Performance Distributors (or, according to one forum member, AC Delco) and keep them handy at all times. Even so, some troubleshooting is required to determine which component is at fault, and changing the magnetic pickup is a PITA - you have to pull the distributor, pull the gear at the bottom, and pull the distributor shaft.

I believe that a DSII with an MSD box and a traditional MSD coil will suffer fewer component failures than a DUI. If true, the root cause of this may be that, without a gasket, the DUI soaks up considerable heat from the engine block, and since the module and coil are inside the distributor (especially the module, which must make solid contact with the distributor body), they are subject to considerable heat, which may lead to early component failure. I live in Houston and ambient temperatures frequently exceed 100 degrees for weeks at a time, which aggravates this heat issue. Remotely mounted MSD boxes and coils won't absorb as much heat; and I believe that MSD boxes may be manufactured to a higher quality standard than HEI-style modules.

Thanks,
Bob

Im hoping my DUI doesn’t have an issue but I’ve gone off the thing, rough running can be anything and he amount of engine components i am now replacing may have led to my rough running or at least erratic tune and timing, i have a 200 with an about to be installed solid cam and a heavily worked 2V head and modified manifold and 350 holley that is also customised, exhaust runs large twin primaries into a 3” collector. My main issue would be component failure, for me locally its about 60 bucks plus for the 4 pin module and as mentioned you can mount an MSD box and coil out of harms way. Plus you don’t have to limit yourself to just a regular 6AL, you can go a 6 digi and other devices that can be added on when things change.

wsa111 wrote about problems with the DUI, one of them being that the shaft bushings are not lubricated properly with the potential for failure. Read it here:
viewtopic.php?f=101&t=72454&p=556660&hilit=DUI+shaft+oiling#p556660

You've already paid for the DUI, I'd recommend having it recurved, and have the shaft and bushings checked for binding.

I live in Arizona where it gets plenty hot and I have not had any component failures on my DUI. Lucky I guess.

The DUI should be fine if vital servicing is done. The design is noted for its hot 50KV spark plus easy service and spark re curving. It does everything the first years Duraspark could do. Its just the HEI mounting and its DUI brand issues that stop it being a first choice.


We are learning more about DUI. I'd personally use whatever FoMoCo part you can find, but remember, the DUI problems are known about, and you can fix them cheaply. If you don't have a Duraspark or Duraspark II, and you can get the DUI for less and not have the substandard replacement parts the Duraspark after market can dribble out, its probably "six of one, half a dozen of the other". The Size of it, the mounting of the HEI, well, its all personal choice. If you don't have Duraspark on your car, it isn't a silly step to get a DUI, but it'll need a little work.

Duraspark II offers a lot of advantages. One of the best is the I6 Duraspark II blue strain relief versions of these distributors to a common Chrysler 5‐pin module. So does the first Duraspark (retro-respectively known as the Duraspark I systems from 1974 to 1975 and in CA till a few years later on some Windsor and 335 based engines).


The earlier system, if you can find them, are better even than the later Duraspark II systems. Ford re-engineered the Duraspark II to allow for safety concerns, and for it to work in cahoots with the emerging Duraspark III system. The earlier i6 Ford and AMC systems have a smaller cap, and the Black or Green strain relief unit, some California market ones are red. The AMC variant used in Jeeps and AMC sedans has its own system, then they hopped over to the Duraspark II.


The Duraspark I system (so called) is a rework of the stock Presolite based Autolite/ Motocraft ignition. Ford bought out Presolites Autolite in 1961. The early Duraspark uses a system that potentially can take a person out with an electric shock. Its primary differences are listed by George P, the Pantera International President Forum Administrator. The info is biased to Cleveland 351 engined cars, but it covers the differences.

cf http://pantera.infopop.cc/eve/forums/a/ ... 7731000846

An OEM style Duraspark 1 module, having dynamic dwell, is one of the most sophisticated ignition modules you can buy. Use it as designed with the proper coil and no ballast resistance and you'll have have an ignition system that properly charges the coil over a wide range of rpm, and an ignition that can ignite mixtures others cannot.

So the MSD 8477 distributor and Duraspark 1 module (with the Duraspark 1 coil) would comprise one of the best distributor based ignitions you could assemble for your Pantera. I can provide Motorcraft & Standard Motor Products (SMP) part numbers for the module and coil if you're interested.

Click to expand...

go ahead and use the DUI since you already own it. as wsa111 suggested have it recurved for your combination for best performance and efficiency. the other thing, when replacing the ignition module when it dies, go with ac delco parts instead of some of the aftermarket parts as the factory parts tend to last longer, and dont forget the dielectric grease when installing the module. one more thing, when replacing the module, dont forget to clean the area where it goes as thoroughly as possible before putting down the new grease.