Shocking!

[Joe C.]

I just found a "238" ignition coil, also embossed "B-R". Can anyone tell me its application.
Also, what is the difference between all of the numbered coils (my 1965 L76 uses a 202). When buying a replacement, all the parts books show a "one size applies to all" of these old numbered coils (except the TI units).
I am using a new, correct, blue stripe (.3 ohm?) ballast resistor.
Thanks in advance.

Joe

[Joe L.]

Re: Shocking!

Joe------

The GM #1111238 is a SERVICE coil applicable to all 67-74 Corvettes, except TI. I don't think that they were ever used in PRODUCTION, but they may have been. It was discontinued quite a few years ago and replaced by the GM #12337166 which is a non-embossed coil.

From a functional perspective, I think that most of these 12V coils are completely interchangeable. A special coil is required for TI applications, but I think that the rest are mostly interchangeable. However, don't get caught on the judging field with the "wrong" one. The "wrong" coil or distributor cap is considered very "gauche".

[Joe C.]

Hey Joe.......

I would never let myself get caught with my pants down! I know that many coils are interchangeable and will "work", whatever that means. Is it a question of current flow thru the points, compatibility to the ballast, output waveform, output voltage, etc. etc? So you see, that I am wondering about the rationale for so many different part number coils, when aftermarket units have almost universal applicabilty.
Truth be told, I am trying to work out a high RPM misfire issue, and am trying to learn how these coils were engineered. I don't want to please the judges, only myself, therefore I want to optimize the performance of my engine. Duke brought up the possibility of points bounce, and I am awaiting a set of Borg Warner A112HP points. I am just looking at the next step, if this is not the fix.
Thanks Joe.

Joe

[William C.]

Re: Hey Joe.......

238 coil was heavily used in Pontiac Applications over several years.

[Joe L.]

Re: Hey Joe.......

Joe-----

I'm afraid that I don't know what the actual differences were among these various GM coils. There may be some ballast-compatibility differences (although I still think that, functionally, they are all interchangeable).

I've always figure that it was like GM starters and alternators. They had a plethora of different part numbers for these things. However, other than a few parts (field and armature; rotor and stator) related to output, there were not that many other differences in components. So, why all the unit part numbers? I don't know.

[William C.]

Re: Hey Joe.......

GM in those days had a lot of engineers and little co-ordination between them. That coupled with the large volume of cars they were building in the 60's allowed a great deal of "optimizing" to suit the tastes/objectives of a particular individual in engineering. I remember a conversation with an associate in Detroit who had a neighbor working for Chrysler. The GM guy asked what he did at Chrysler, the Chrysler guy answered he was the Radio Release engineer. The GM fellow asked what line he released for, as GM had at least one per platform. the Chrysler guy responded "I am THE radio release engineer for Chrysler!"

[Art A.]

Re: Hey Joe.......

Bill, guess how GM does it today! Yep, One release Engineer for a given part for multiple vehicle lines. Maybe not the all the vehicle lines, but a lot more than in the days of old.

Art

[William C.]

Re: Hey Joe.......

Yes, I was there until 2001, I saw the pendulem swing both ways. it's amazing what competition will do, and how much can be ratonalized by enormous volumes. Of course, Engineering technology has changed a lot also, but looking back with 20-20 hindsight there certainly was a lot of redundancy in the "old days"

[Dan Tewell]

Re: Hey Joe.......

Joe,
If there was any doubt about point bounce, why not get rid of the points altogether? Pertronix and Crane both make excellant conversion kits that fit entirely under the distributor cap. The Crane one even has a rev limiter!

Dan

[Terry M.]

coil # differences *TL*

Some of the embossed number differences are due to the coil bracket. In many cases the coil and bracket were shipped to the assembly plant together as an assembly. Thus the coil and bracket had a distinct part number, the last three digits of which were embossed into the coil. The service coil would then have a different number since it came without the bracket.

[Joe C.]

Re: Hey Joe.......

Thanks Dan. Yes, I have heard about these conversions, but for the time being, I'd like to get the old beastie optimized in its original trim. There'll be lots of time later for dressing her in modern clothes.

As of now, I'm eliminating either/or points, or a weak (??) coil. It has been raining here on the east coast for so long now, that I saw a large wooden boat go down my street yesterday. The guy at the helm had a long white beard, and there were a bunch of animals on board. If the sun ever shines again, I'll take her out for some testing.

Joe