http://www.davessmallbodyheis.com
i found this over at the Hamb. would this be the same as the D.U.I. system.
i found this over at the Hamb. would this be the same as the D.U.I. system.
the same as D.U.I.?
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The DUI is a high quality properly built and tested coil in cap setup so its neat and clean with only 1 wire hookup. Uses GM style parts that anybody and everybody makes and stocks.
I imagine both companies are going off the same concept, which is to modify and properly build (or build from scratch) the HEI's to fit other motors. The only HEI's that were prone to some problems were the last generation before the current one (starting in 96 i think) The cap was a flat crab like thing were the wires came off in line in the physical order of the motor rather than the firing order. This version was prone to cross fires. The coil in cap was in almost every car and truck (except some 4 cylinders) from 74-86. The small cap was in everything 87-95 except for the LT1's with the optical setup.
The important factor if you are going to be paying big bucks is to make sure they are quality parts that are properly set up and tested for your application. Typical parts store new and rebuilt models are marginal quality as far as bearing fit and such and you never know what you are going to get for curves.
The important factor if you are going to be paying big bucks is to make sure they are quality parts that are properly set up and tested for your application. Typical parts store new and rebuilt models are marginal quality as far as bearing fit and such and you never know what you are going to get for curves.
NOT the same as D.U.I.
I've got one of Dave's small-body distributors (triggering an MSD box) on my Buick 455, and have read a ton of Dave's (aka Ignitionman) postings on the various Buick boards for awhile. He does good work, even if he can be opinionated. Like me, he HATES the GM in-cap coils because they overheat and start misfiring above 4500 rpm. There are 2 causes to that: 1. epoxy-filled coil, and 2. it's buried inside the cap with no ventilation. GM knew this for years, but since few oem cars stress their ignitions that much, it wasn't a big deal - more than offset by production / maintenance concerns.
Dave does EXCELLENT work - his distributors are works of art, period. I don't see how he does everything he does for the price he charges (iirc, he even hard-chromes the dizzy shafts for durability)
On the downside, Dave can be hard to get ahold of, and you can expect a month or so turnaround time.
I've got one of Dave's small-body distributors (triggering an MSD box) on my Buick 455, and have read a ton of Dave's (aka Ignitionman) postings on the various Buick boards for awhile. He does good work, even if he can be opinionated. Like me, he HATES the GM in-cap coils because they overheat and start misfiring above 4500 rpm. There are 2 causes to that: 1. epoxy-filled coil, and 2. it's buried inside the cap with no ventilation. GM knew this for years, but since few oem cars stress their ignitions that much, it wasn't a big deal - more than offset by production / maintenance concerns.
Dave does EXCELLENT work - his distributors are works of art, period. I don't see how he does everything he does for the price he charges (iirc, he even hard-chromes the dizzy shafts for durability)
On the downside, Dave can be hard to get ahold of, and you can expect a month or so turnaround time.
jamyers":1okphmgr said:
There is also this. Many GM people pushing the limits of their engines go to a divorced coil setup.
I did.
Coil-in-Cap HEI is convenient, clean, and easy to install.
But it's probably not the best choice for high performance applications.
They still all function the same way however - it's just a question of where you put all the parts.
Bort62":ipjeaafa said:
Yup. And you can use the Duraspark to trigger an HEI module to fire an HEI coil; all of which can be found at the junkyard for cheap.
Or you can buy brand new stuff that works not one whit better. Ya pays yer money and ya takes yer choices
Joe
Yup, I don't think you can beat it until you get up into the full-race high-rpm or maybe nitrous world. Even then...Bobscoupe":3p5p780n said:
Edit: For a Ford, that is. For a GM, I'd go with one of Ignitionman Dave's small-body HEI's any day.
The whole spark thing is pretty complex with a lot of variables. To compare systems you need a lot more info which 99% of them dont give you. For stock / street type of applications any of the stock type of systems are going to do fine. The capacitive discharge and multi spark systems (MSD 6) make a difference under some circumstances. The big reason to go with a system like the dui is its a high quality piece that is properly set up and tested for your application. Dont worry about the voltage stuff, a lot of that is just like HP ratings, they can get any number they want by setting up the test the way they want to and not giving you all the info. An engine may be able to make 300 HP but its at an RPM range that you would never be able to use. Same thing with ignition systems. They can have a system that can generate a gajillion jigawatts but if you hook it to a spark plug with a .050 gap its still going to jump the gap in the thousands of volts range and chances are you are going to be expecting it to finish and be on to the next cylinder before it would have time to deliver a lot more voltage. It all happens in milli or micro seconds so its hard thing to comprehend and even harder to do anything about without all the tools and knowledge. There are a lot of other (easier cheaper) things you can do to get better performance out of your car before you have to worry about details like spark voltages. By the time you are on that level you will understand the engine as a system and know what you are need to take advantage of different sparks.
However spark curve is something that's different on each motor. You can't build a single dizzy that has the perfect spark curve for all motors. Mine, with a 264 cam advanced 4 degrees and a H/W 5200 on a log head will require a much different curve then Mustang Geezer's.
A properly setup DUI will not make anymore power than a properly setup DSII but you will pay alot more for it.
Bob
A properly setup DUI will not make anymore power than a properly setup DSII but you will pay alot more for it.
Bob
primal1":3tpbz9sw said:
There is neither conclusive evidence (one loosely controlled test does not qualify as conclusive evidence) nor any technological justification that it does.
It is the same functionally as a DSII, only packaged differently.
Same components, different places.
The "one wire" installation and look are worth the extra price to some people.
Also, the above statements about quality may be true. I can't pass judgment one way or another on the DUI's quality as I don't own one. I do know a lot of the DSII setups that come out of the parts stores are fairly low quality, so I would imagine the DUI is better in that regard.
I personally do not feel that the DUI is worth the added cost, but that is just my opinion. Sometimes my opinion tends to not be too popular around here
YMMV.
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