I'm building a 261 I6 for my 48 Chevy coupe. I've been reading reprints of old inline speed manuals and they suggest using a dual point distributor and dual coils. I have a dual point Mallory, so I'm half there. What's the advantage of having two coils (other than looking cool) and how would you go about setting them up? yes, I know HEI would be easier, but I'm trying to keep this as close to 50s/60s "period correct" as possible.
When I rebuilt the distributor on my car I decided to read the whole chapter in the shop manual regarding it. As far as I could tell the only reason there are two points instead of just one is so that the coil can charge itself up more (the points don't operate at the same time, they're slightly stepped from each other, which is why the car ran with only one point in it). I can't think of how you could even hook up two coils, much less gain an advantage from them.
I've never heard of running 2 coils with a conventional distributor cap.But I'm sure it's been done.I'd rather run 1 coil per cylinder.If you used the old style coils,instead of the latemodel coil pack shit,it would look good and work even better.
on a W&H DuCoil distributor for one.. and the reasoning is that it gives double the saturation time. Paul
[ QUOTE ] on a W&H DuCoil distributor [/ QUOTE ] Thanks, Paul. Where might I find one of those? I just did a search and came up with 2 mentions buried in various sites, but no info on DuCoil or W&H. Is it a vintage only part or do they repop them? WOuldit work with a vintage Mallory? Thanks.
You need more than a special cap. You need a special rotor and an adapter for the second coil. I'm betting the points need to be relocated to fire on time for the second coil. This is a Harmon-Collins for a flat head. There was the Ducoil(sp?) and the Spalding/Grant dist. from the 60's. Anything is possible but converting a dual point dissy to be a dual coil dissy aint easy. P.S. the fireing order is different on this one to get the double ended rotor to fire the correct plug at the right time.
Hellfish, yes that is vintage only and if someone were to repop the caps and rotors they would have a very hungry bunch of customers. I don't think I've ever seen one for a six though.. 'not saying they didn't make 'em, just that I haven't seen one. I just went out to the shop and dug around for my sbc unit but since I moved I can't find a damn thing! I usta have a couple for the early Olds' motors but, again that's an 8.. Paul
The W&H Du-Coil ignition uses two coils.There was one on my 57 Safari before I got it and I'd love to find another as my tach has a 4 cyl. sending unit(for the DuCoil). Lakesmod gave me a phone # of a guy in Washington State(I think)who has NOS DuCoils.He didn't have one for a Pontiac but might for the Chevy.His e address is in the members list.
Thanks, Safari, I'll check it out. So, I don't just need a special cap, but a whole new distributor. I get it. And I'm betting parts are real easy to find, too.
I know it might have been overlooked, but this 31 roadster is running dual coils. Evil knows this guy. Evil??
Dual coil distributors came into being because the ignition systems of the day couldn't handle the rpm levels being attained. A great part of it brought on by the high revving SBC. You probably won't need it at the rpm levels you're going to run your six at and like was said, parts availability could be a problem. That said, the Ducoil - if I remember right - took Ford points and condensers and in fact the condensers were on the outside of the distributor body. What I would do if I wanted a killer ignition - and having lived with and ran one for the last bunch of years, it's a good place to spend some hot rod bucks. An amplifier box like MSD. (Put it in a cool place regardless of what the instructions say, my 32's is under the cowl away from engine heat.) A quality USA made oil filled coil. Jacobs makes a good one, $25. about 8 years ago, probably not over $35. now. Use a good quality points set with fibre rubbing block to trigger the ignition or do the Pertronix bit. A good stock condenser with neoprene rubber seal where the wire comes out and not the cardboard bit for the wire exit. Toss the factory supplied points lube and buy a small tube of silicon points lube and use it sparingly. The rubbing blocks last a long time with the silicon stuff. Granted, sometimes hard to make yourself spend enough money to buy a cam and kit on an ignition, but it's money well spent. A good ignition makes for easy starting, ridiculous rpm abilities for a street engine and a tiny bit of a horsepower gain at low and mid-range along with subjectively feeling smoother at low speeds. Not to mention that if you're a newbie or even unsure about the wiring system on your car, installing this stuff will make you a lot more confident in your abilities to trouble shoot if problems arise. Follow the instructions and more than likely you won't have any trouble. The Ducoil dual coil ignition goes something like this. A rotor with double ends. The rotor also has the center graphite rubbing button in the middle as the stockers do, but it has an additional graphite rubbing button about half way out on one arm of the double ended rotor. This additional button rides against a brass circular ring on the underside of the distributor cap. The brass circular ring connects electrically to the offset coil terminal on the distributor cap. Dual points and dual condensers give - for the V8's - what is in effect two four cylinder ignition systems in one package and what makes it work is the additional coil saturation time gained. The Ducoils work very well with quality stock coils. The only other trick is you have to use a different firing order. The commonly used GM firing order: 1-8-4-3-6-5-7-2 is changed to 1-5-4-2-6-8-7-3 You can plot any firing order on V8's by remembering the next cylinder to fire is 225 degrees away from the one that just fired. Keep in mind the double ended rotor bit. Was all that clear? Hope so....
Good info C9 but, just to clarify: the firing order remains the same, it's the wire araingment on the cap that changes. Paul
I went through some of my vintage speed equipment catalogs and as far as I can tell W&H Ducoils were never made for 6 cylinder engines.
Heres my DuCoil for the Chevy V8 anybody have a spare breaker plate, points and rotor for this? I seem to have let mine go when I unloaded my Olds units oops
Hey Joe, like C9 says, those old manuals were written in the days of 6 volt systems. That being said,according to the California Bill book I have, they built a dual coil dizzy using a Stewart Warner mechanical tach drive for a Chevy six and an old Nash 6 cyl. dizzy that rotates clockwise. Sounds like a bit of work but would sure look cool. I've seen a few of those tach drives on E-Pay in the last couple of years.
Yeah, that's one of the books I was looking at. I think my dual point mallory has a mechanical tach. Not sure about the stock one.
"I've never heard of running 2 coils with a conventional distributor cap.But I'm sure it's been done." It was done in the fifties on one of the cheaper imitators of the Harmon Collins oictured above. I have bits of one of these things, but have no idea how well it worked--it seems a bit crowded for a high voltage application. It was made about the same way for '46-48 and '49-56 Ford applications, at least. This company (there are ads in ca. 1950 HRM, but I can't remember their name) drilled two small holes through the 59A and 8BA style caps beside the coil terminal and ran two small machine screws through into a ring of brass about 1/2 of the way between the coil terminal and the cylinder terminals. A small piece of strip brass was screwed to the counterbalance on the rotor at 180 degrees from the stocker and shaped to meet the new ring and the outer terminals. The point plate must of course have been redrilled for the alternate point arrangement and the cam ground down to four lobes, but I don't have a base for this unit and can't describe. Anyway, voila--a dual coil for next to no expense and not even that much work. Perhaps an idea for all the poor souls who have discovered that every H&C conversion on the planet is riddled with cracks... A screed I posted on dual points some time ago: "The overlapping dual point set up is a 1920's Mallory idea since used on '32-48 Fords and most aftermarket points distributors, along with all of the HP factory distributors of the fifties and sixties. Both point sets are part of the same coil grounding circuit, just the way a single point would be. The points are stagger mounted so that they open and close about 10 degrees apart. BOTH points must be open for coil to fire, but only ONE needs to be closed to allow coil to charge up for the next spark. Longer charging time=better spark, especially at high RPM when the times between sparks are very short. So, as the distributor turns, point one opens--nothing happens, coil still charging because is still grounded by point 2. Then, point 2 opens, and coil is disconnected from circuit and mysterious demonic forces angered by loss of their electricity fire the spark. Then, point 1 closes, which is happening substantially before the timing point (2) can close--coil starts to recharge its field, allowing more time than if it had to wait for the timing point to close. The extended time cannot be obtained with just one point because of constraints in cam design. This was important stuff in the thirties when coils were primitive and frail--Ford needed it in 1932 because of the flathead's eight cylinders and its very high for the time RPM curve. Another available solution was dual coil, two points operating alternating cylinders with two separate coils--even better, but more costly. I doubt that this stuff matters any more on engines at streetable RPM limits because modern coils are pretty good, and on any modern system needing more capacity the problem would be handled via electronics and maybe individual coils."
Hey Joe, ya gonna build a stroker like in the new 12 Port News? I really like my 216's, but that stroked 261 really looks like a tits setup. Got me thinking about lookin' for a 261.
I ran a Harmon&Collins on my flathead back in the 70's, and it worked great with no problems except when a condenser went south. i got home on 4 clyinders ,as only one side died.new condenser and i was off and running again.ran it without touching it for over 7 years and was still running great when i sold my 27 t roadster pu. i know some one who has a NOS small block chev. unit, but it will not be cheap, but it's brand ass new. Peter of rodandcustom fame, is selling me his W&H for my olds engine. been looking for years and knew he had one. when i asked him if he knew of any others, he said why not buy his, so here i go.i don't ever remember seeing one for a 6 tho.
[ QUOTE ] Hey Joe, ya gonna build a stroker like in the new 12 Port News? I really like my 216's, but that stroked 261 really looks like a tits setup. Got me thinking about lookin' for a 261. [/ QUOTE ] I'm waiting for that issue to arrive. I've been looking for a 261 for years, but could never find one nearby. I just picked up one cheap and I'm hoping it's good. Boring it and Stroking out to 290 is VERY appealing, but I'm concerned about its drivability that way. I want to be able to drive it on long trips... like to Texas. Thanks for all the info/advice guys!
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