MSD vs. DUI
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Senior User
Joined: Feb 2004
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From: Crownsville, MD
MSD vs. DUI
I am thinking I may need to upgrade my distributor after I install new heads, intake, cam, etc. I currently have a stock Ford distributor with the Duraspark system. I have seen posts recommending both the MSD and DUI distributors, but everyone always points out that the DUI is expensive (not the MSD). After a quick check, I see the DUI is about $375 and the MSD is about $340. Not a big difference. Am I looking at the wrong parts or is there something else you need to buy with the DUI that I am not considering?
More importantly, which works better and is easier to use? I have heard folks say that DUI will set your advance curve for you based on your build. What does that mean?
More importantly, which works better and is easier to use? I have heard folks say that DUI will set your advance curve for you based on your build. What does that mean?
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From: Long Island USA
I still have the stock Duraspark dizzy (1976) in my '74, but mated to an MSD 6AL (multi-spark) with a somewhat hotter MSD coil (stock sized). HUGE DIFFERENCE from the Durspark ignition module and stock coil. Smoother idle (big cam), better cold start and cold-running, etc.
Except for recurve and vacuum advance (or lack thereof) I see no reason to upgrade unless your dizzy is worn out, or just not "pretty" enough
And I'm sure you can find a recurve kit for the Motorcraft dizzy.
Timing is very steady at idle, and it runs up past 6000RPM with no problems, so the Duraspark pickup in the dizzy ain't all that bad.
I have no idea what a DUI is, so I'm just letting you know what I did.
Except for recurve and vacuum advance (or lack thereof) I see no reason to upgrade unless your dizzy is worn out, or just not "pretty" enough
And I'm sure you can find a recurve kit for the Motorcraft dizzy.
Timing is very steady at idle, and it runs up past 6000RPM with no problems, so the Duraspark pickup in the dizzy ain't all that bad.
I have no idea what a DUI is, so I'm just letting you know what I did.
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From: Oregon
The DUI is more reliable and easier to hook up than the MSD. The DUI is all that you need, you don't need to buy additional stuff for it. Thats where the "unified" in DUI comes from One wire hook up. I've run stock, DUI, and MSD and all have their repsective place. All the custom curving means is that they hook it up to the dizzy machine and set up the curve matched to your engines specs. There was pretty long thread in here last year on this topic, with several good opinions.
One wire hook up. I've run stock, DUI, and MSD and all have their repsective place. All the custom curving means is that they hook it up to the dizzy machine and set up the curve matched to your engines specs. There was pretty long thread in here last year on this topic, with several good opinions.
Lead Driver
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From: Texas
DUI is a one piece solution. You need only the one part and one wire! It also cost less than the MSD Billet+MSD COil+MSD 6 ignition.
It does not offer the multispark of the MSD.
If I knew about the DUI when I bouight my MSD, I'd be running DUI.
Now, if it came down to a very controlled test the MSD would probably burn more fuel at various RPMs (better mileage, more power). But, I bet the difference is in the less than 3% range. Of course , I pulled that number out of my !@#$.
It does not offer the multispark of the MSD.
If I knew about the DUI when I bouight my MSD, I'd be running DUI.
Now, if it came down to a very controlled test the MSD would probably burn more fuel at various RPMs (better mileage, more power). But, I bet the difference is in the less than 3% range. Of course , I pulled that number out of my !@#$.
Post Fiend
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From: Oregon
Greg, I think your dead on about the mileage issue, given that both systems were optimally tuned. However, I actually picked up mileage when I swapped the msd system out and replaced it with the DUI. The reason? I'm sure it was because the curve on my MSD wasn't optimal where as the DUI was dead on. Point is, I doubt anybody will lose mileage with the swap, they'll probably gain it. I only use the MSD on the '73 with the race engine. If I see the need to replace the stock setup on any other rigs, they'll get a DUI too (which was put on my mildly hopped up 428). The only time I'll take a msd over the DUI is for full out race engines.
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From: Maple Ridge BC Canada
OK not trying to start an argument, but a properly curved dizzy will give better mileage period....Msd, DUI or W.H..Y.....The real advantage is the msd will give a spark like an arc welder...so at times with engine temps, cold or just warming up....the MSD always fires...The advantage of one wire hookup is kind of cool...but I wired a ignition cutout to my cigarette lighter...I can also limit my rpm (6AL) try that with a DUI.....IMHO...the msd is worth the money...D44HD...
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Senior User
Joined: Feb 2004
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From: Crownsville, MD
Is there such thing as a recurve kit for the stock Ford dizzy as krewat suggested above? If so, I may just do this as a temporary solution after I install new heads, cam, intake, carb, etc. I have been told that after my build I will likely need to do something with the stock distributor because they have horrible advance mechanisms in them resulting in a rough idle or too much advance on the top end. Installing a recurve kit would be a cheap solution until I can get enough scratch together to get a DUI or MSD distributor. Based on the discussion above, I think the DUI would be the better and cheaper choice for my mild-moderate build. Thanks for all the information.
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From: Oregon
Originally Posted by d44hd
OK not trying to start an argument, but a properly curved dizzy will give better mileage period.
Senior User
Joined: Aug 2003
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From: Maple Ridge BC Canada
Proeliator....I dont disagree, most of us dont have a distributor machine..but you can come pretty close with a tach, a couple of springs, and a timing light...I guess I just have a problem with Chevy parts on my Ford...LOL....
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From: Texas
Originally Posted by d44hd
Proeliator....I dont disagree, most of us dont have a distributor machine..but you can come pretty close with a tach, a couple of springs, and a timing light...I guess I just have a problem with Chevy parts on my Ford...LOL....
Yeah, but where do you draw the line. Ford only made the block, oil pan and timing cover in my motor. It's really more of a "Cranedelbrock" or somthing :-)
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From: Smith Mountain Lake, VA
Well I have to disagree with being able to get real close just with a spring kit and some stops nd a timing light...Unless your REAL lucky..
Back when My partner and I had are little Chebby Chop...I had the Sunnen pro curve Machine there...and Guys that I raced with thought they were right on it...
And found out after I ran there dizzy's on the machine at What ever RPM range they were running in, some might have been close, but more were way out in left field...And after I recurved one..to the specs of the build and the use of the motor..I never had anyone come back... they were drop in and go!! Russ
Edit.. And PS...I dont know how you can burn fuel anymore than with a 50,000 volt charge in a cylinder? I think for most the DUI is the way to go...JMHO.....
Back when My partner and I had are little Chebby Chop...I had the Sunnen pro curve Machine there...and Guys that I raced with thought they were right on it...
And found out after I ran there dizzy's on the machine at What ever RPM range they were running in, some might have been close, but more were way out in left field...And after I recurved one..to the specs of the build and the use of the motor..I never had anyone come back... they were drop in and go!! Russ
Edit.. And PS...I dont know how you can burn fuel anymore than with a 50,000 volt charge in a cylinder? I think for most the DUI is the way to go...JMHO.....
Last edited by RapidRuss; Jul 30, 2004 at 09:46 AM.
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