I'm building a 303 Rocket Olds mill for my 33 Ford Coupe. Lately I've been seeing alot of DuCoil dizzy's up for sale on 'that auction site'. I think they're cool as fuck but do they work okay? Or is it better to find a Mallory dual point distributor?
From what I have been told, they work great.The only drawback is no vaccume advance & parts for them are hard to find & spendy most of the time, but I have one for my 303 olds anyway, as well as spare parts.I have a Mallory as a backup tho.
I think it might be for racing. Why dual points? If one fails is what I would imagine. On a 360 degree crank, only one cylinder fires. Twin cylinder to a v12 Ferrari. I could be wrong, but it is still one cylinder fire at a time in one crankshaft revolution. Coils, sorry. I thought it was points. Dual coils are another backup system. One spark is all that is needed out of a coil. The other coil is overkill.
JFYI Dual coils ignition systems for the V8s of the 50s and 60s were made up of 2 separate 4 cyl ignition sytems. One set of points and a coil for 4 cylinders with another set of points and a coil for the other 4 cyls. The theory was more dwell and less point float at high RPMs. They required special rotors and caps to accomplish it. Those are the expensive parts to find today. I ran a Spalding Flame thrower for a while and it worked just like any other distributor. Mine did not have the vacuum advance option so it might have hurt my gas mileage a bit but the eye candy aspect more than offset that minor distraction. IMHO If I were going to drive across country I'd carry a stock back up dizzy or the spare unobtainium parts just in case of an inopportune failure.
Tommy nailed it. The Ducoils could carry a lot more RPM's than most single or dual point ignitions of the time. Dual points have more dwell than a single point system due to one set of points makes the circuit and the other set breaks it. I ran a Ducoil on a Rocket Motor. It was a nice setup. I used K-Mart coils fwiw. Chosen because a motorcycle magazine guy did some research and wrote an article on adapting car coils to bikes. He found that the K-Mart coils - at that time, eary 60's - were the best in terms of spark output. Research was done on a hacked together setup utilizing a lathe, battery wiring etc. Kinda crude, but it did the job. Anyway, I only had two problems with the Ducoil in several years of running it. Both my fault and helped along by the spray wand at the two-bit car wash. The first one, I'd installed new condensers - Ford items, about 1950 or so. The condensers were on the outside of the distributor body. I had the wire end terminals too close to one another and after some time went by, a corrosion-like ridge of green stuff grew between the condenser terminals. The engine developed a miss that couldn't be interpreted by the Edison Company garage's new oscilloscope. The mechanics thought it would, but the pattern shown was like nothing depicted in the oscilloscope manual. I finally found the problem, cleaned things up and rotated the terminals so they weren't so close. The other problem was the cap developed a carbon tracking path. That one due to moisture from the car wash spray wand. I covered the cap most times, but screwed up anyway. If you have a carbon-tracked cap, all is not lost. I talked to the electricians at work, one of them gave me a small can of Glyptol, told me to grind the carbon track out and paint the interior of the cap. I did and it worked fine. I'm reasonably sure the Ducoil points are simply 50's era Ford points. They looked familiar when it came time for new points and the local parts guy was able to locate a pair of Ford points - and condensers - that worked fine. Any condenser from any car that physically fits will work. All of them have the same MF (Micro Farad) rating.
Along the lines of running the Ducoil on RoyalCrown32's Rocket Motor, I'll probably start the engine - 462" Buick in my 31 on 32 rails roadster - and run it for a while on a slightly re-curved stock (vacuum advance) distributor. The MSD distributor is - or was - appealing to me, especially since they came out with a vacuum advance model. After reading a few ignition related posts on the Buick V8 board and their comments about the Mallory being a better distributor I'll probably spring for one of those. Gotta admit though, the Mallory dual point distributor is appealing. If for nothing else to bug my electronic minded pal. He forgets that cars ran points ignition for many years and ran well with the 10,000 - 12,000 mile yearly tune-up. Not to mention that points ignitions are serviceable in the field. Granted, electronic distributors are pretty much "plug and play", but looking at my 32 roadster with 46,000 miles in 14 years that's only 3-4 "tune-ups." I like tinkering with it anyway....
Glyptol on rare plastic is a GREAT tip!! '42-48 Ford original caps came with some sort of tan-colored paint inside...I'm guessing it was some ancestral form of Glyptol. For those who are stuck on plastic bits...I think a Ford '56 type cap fits on these with the adaptor ring removed from casting, then there's a tick way to convert those to dual coil...
Glyptol is still available. Check at an industrial electric supply type place. Even then, the Ducoil cap cost an arm and a leg. I think a stock distributor cap went for $3. a the time and the Ducoil cap was $12. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As a little side comment on speed equipment prices, we're lucky today. Back in the day, discounts on speed items were hard, if not impossible to get unless you actually worked at a parts house. When the 60's came along and many young men turned their back on hot rods and cars, speed equipment manufacturers were no longer able to charge high prices due to the lower demand for speed parts. With the recognition that the competition was on for fewer and fewer discretionary dollars, prices got more reasonable and the stuff got discounted at more than a few places. I the end, it was good for the speed equipment industry and especially good for us.
Friend of mine has been running a Ducoil on a 283 since 1957. Raced it for many years. No problems. I have a '56 265 bored to 283 that has a lot of history, I am going to run a Ducoil just because I have one and it will fit with the period engine.
They painted the inside of the old Harman Collins dual coil caps with glyptal. Seems the old plastics weren't quite the insulator of the stuff we have today and they had arcing problems through the caps.
Just to add a little to what C9 wrote - not ALL dual point distributors work the same. Some are as C9 stated while others work with one set of points firing 4 of the 8 cylinders while the other set of points fires the remaining 4 cylinders. When in doubt how your works simply look at the cam lobe. If it has 8 "bumps" it works as C9 stated. If it has 4 "bumps" it works the other way. FWIW
And Mallory made both, the four lobe rotor was for increased RPM's, but the normal dual point will rev past 7500, how many of us need more than that?
They are great distributors. As said the caps normaly if you find them are around 100.00 to 125.00. They rotor is the tuff one. The little tab that slides in the groove on the distributor shaft is what always breaks. I would deal with the little issues to have a DuCoil distributor then a common Mallory. Something about the two coils looks so good. Just my opinion. Good luck. Steve Glucoft Amocat spd emp.
The mallory ducoil requires a special mallory ignition coil, hers a couple pics of the one i run on my HA/GR GMC car. It has two primarys and a single wire to the distributor cap. The only issue is that it takes a four cylinder tach for a v8 and a three for a 6 cylinder. I found a nos extra coil on ebay just in case. Hasnt been a problem yet...
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