Early Delco Round Type Ignition Coil Reproduction

[Peter R.]

I‘m planning to reproduce some early Delco round type ignition coils for my project (1913 Cadillac) and was wondering if there‘s a general demand for such coils.

 

The goal is an original looking coil, newly wound and entirely made with modern materials.

 

I have several sample coils in stock to take measurements from.

 

I‘m considering to do the following coils:

 

Delco 2093

1913 Cadillac (Battery Coil)

 

Delco 2111

1915 Auburn 6-40 (Cont. 6-N)

1915 Buick, all models 

1915 Cartercar Model 9

1915 Jackson

1915 Moon

1915 Oakland, all models

1915 Oldsmobile, all models

1915 Paterson, all models

1916 Sayers-Scovill (Cont. 4-C)

1915 Westcott, all models

 

Delco 2115

1915-23 Cadillac

1921-23 LaFayette

1923 Peerless Model 23

 

I will also consider doing other round type coils.

 

Any comments appreciated.

[tom_in_nh]

My hat is off to you, Peter.

Manufacturing goods for the paying customer is no small feat.

I wish you nothing but the very best of luck in this endeavor. 

Best regards, 

Tom

[Dandy Dave]

I would be on the list to buy one or two. I have a dud around here that I looked into quite a while ago thinking the same thing that you are. Even if there was a way to put a modern coil inside of my old casing and still use the original lugs would that would be fine. The one on my 1915 Buick still works but I keep waiting for it to give up. Amazing it still works after 108 years.

[cxgvd]

Same for me, as Dandy Dave says, for a 1915 Buick.  McLaughlin.  Gary

[Larry Schramm]

Peter, I might be interested in one or two like Dandy Dave, depending on price.

[edinmass]

Here is a suggestion. Buy a  Bosch 4.5 volt Mercedes coil, used in the 90’s. Hide it inside a reproduction coil body. It will fit easily, throw a spark like a lightning bolt, and you can easily carry a spare coil to change out if the modern unit fails. That’s what I did on my 1914 Caddy. 

[Larry Schramm]

5 minutes ago, edinmass said:

Here is a suggestion. Buy a  Bosch 4.5 volt Mercedes coil, used in the 90’s. Hide it inside a reproduction coil body. It will fit easily, throw a spark like a lightning bolt, and you can easily carry a spare coil to change out if the modern unit fails. That’s what I did on my 1914 Caddy. 

 

Ed, by chance would you have a part number or a specific vehicle year and application? Thanks

[edinmass]

I will have to look it up. It was fifteen years ago. I might still have my notes. The coil threw such a hot spark it was insane. The Mercedes computer system operates at 4.5 volts…….so the six volt system doesn’t damage the coil. 

[Peter R.]

Ed, did you use an extra resistor with the coil or did you just run it at 6 volts?

I can gladly look up the 90‘s Bosch coils and procure some of the coils in question, if someone wants me to. I‘m sure it won‘t be a big thing to hide one inside a coil body.

 

However, a hot spark is one thing but one should really look at the system as a whole. I can easily wind the coil so it gives a much hotter spark. But one should keep in mind that the breaker contacts of a conventional coil ignition system should not interrupt more than 5 Amps of current in the primary circuit or the points will wear (burn) prematurely. So the number of windings in conjunction with the thickness of the wire are the limiting factors when using mechanical breaker contacts. Modern ignition systems do not depend on mechanical breaker contacts because they interrupt electronically. Therefore coils are wound for much higher primary currents to be interrupted, which results much higher high voltage outputs (hotter sparks) in the secondary circuits. Besides this the secondary circuit pushes back up to 500 volts into the primary circuit (resonant circuit). Modern coils push back more voltage, which will easily blow those old condensers (I‘m using modern condensers at 1’000 VDC and 0.22 micro Farads capacity). In my opinion an over 100 years old ignition system is not designed for such high voltage outputs and one will sooner or later run into other problems. So I‘d be careful just using a modern coil in such an old car. 
 

There are other improvements that can be done in order to optimize performance and reliability of the old coil design by using modern (better) insulation and iron core materials or by first winding the secondary winding and wind the primary over the secondary instead of vice versa etc.

 

First I would test an original coil on a running car with an ignition oscilloscope so I can see how the system performs, thus reading out ignition voltage (voltage required for the spark to jump the gap at the plugs), burning voltage, spark duration etc. -> to determine min. energy required).
Then I would take apart the coil to see how it was wound back in the days (wire thicknesses and numbers of windings on primary and secondary circuits).

Finally I would start to calculate, compare and optimize so I will get a coil that has enough energy to produce the hottest spark possible (spark length on the tester) at 10‘000-12‘000 volts secondary (output) when breaking max. 5 Amps in the primary circuit.

[Peter R.]

Some early Delco coil types and it’s internal circuits. Some coils are grounded, some have one and some have two secondary terminals, some have the condensers incorporated and some come with resistance units on them (they‘re either mounted on the coil or on the distributor).

 

 

[Peter R.]

The modern paper or cotton reinforced phenolic laminate tubes that I will use for the coil housings.

 

 

[edinmass]

Peter, we ran the coil at six volts. My educational technical background is in finance and economics. I’m self taught and have only read up on coils from an amateurs perspective. I wasn’t aware of the five amp rule passing through points. I thought the number was seven or eight. The 1914 Cadillac had the serviceable points in it. My car had 7000 original miles, and was running on the factory coil and condenser. (Over 100 years old.) Both were having trouble……and I was also fighting fuel pressure and mixture problems so at the time I was just trying to get past ignition issues to continue forward with the fuel. The coil trick I did worked well, but I never put more than 500 miles on the car before selling it. It’s certainly possible over time my modifications would have caused burning points. My over pressure on the fuel system was fixed by a pop off pressure valve as I couldn’t get the car to stop over pressurizing the fuel tank. In the end the car was running reasonably well. When I look back at it, I should have replaced the factory plugs……..I’m guessing they may have been a problem also. 1914 had the heating element in the float bowl to make the fuel vaporize for cold starts. It was still connected and working when I purchased the car. Talk about a fire hazard. 

Edited November 25, 2022 by edinmass (see edit history)

[edinmass]

Here is an example of why old coils shouldn’t be run. For years it seems that running 50-70 year old coils was ok, but in the last ten years I have seen lots of coil failures on tour and in the shop. Now I automatically upgrade to modern coils before I even try and sort a car. On many exotics replacing the coils isn’t always straight forward. In the test below the car was running on 85 year old coils but occasionally had a running problem. When one actually tested the coils on the bench it was hard to believe the car would even run. I have only recently been having coils custom wound to replace the factory units……it obviously gets very expensive real fast. Best, Ed.

 

 

 

[SC38dls]

Ed, you didn’t know about coils and 5 amp limitations because the dark side was trying to get you into post war cars even then. 
dave s 

[Mark Shaw]

On 11/24/2022 at 4:36 AM, Dandy Dave said:

Even if there was a way to put a modern coil inside of my old casing and still use the original lugs would that would be fine.

Me too...  What price do you expect for the 1915 Buick coil?