Chevelle Tech - View Single Post - HEI Coil Wire Color Difference...
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post #2 of (permalink) Old Jun 20th, 19, 1:22 AM
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Re: HEI Coil Wire Color Difference...

Originally Posted by WakkoWarner View Post
I have always wondered what the difference is between the HEI coils that have red/yellow wires, and the ones that have red/white wires. Several years ago one of my cousins had a Cadillac that wouldn't start. Through the course of diagnosing it, I determined that the coil was bad. His had the red/white wires. I had one in my trunk that had the red/yellow wires on it. I installed it and it started right up (I used what I had, because he didn't have any money and it enabled him to get to work).

I didn't hear back from him, so I presume that it kept working. So, what is the difference between the two??
see tech reference = scroll way down
Coil interchangeability

The coil-in-cap ignition coils need to be matched to the pickup coil, and the pickup coil must be matched to the engine family. There are two color-coded ignition coils, and three color-coded pickup coils. (Note that external ignition coils are not color coded to the pickup coil.) One coil-in-cap ignition coil uses red and yellow wires; the other uses red and white wires. They are functionally identical except the magnetic (not electrical) polarity is opposite. One pickup coil uses either a yellow tyrap or a yellow plastic connector body on the wires that attach to the module. Another pickup coil uses either a blue tyrap or black plastic connector body, and the third pickup coil uses a clear tyrap or a clear plastic connector body. (Some aftermarket manufacturers will use no connector body instead of a clear one.) The yellow coil has opposite magnetic polarity from the blue/black, and clear pickup coils.

Delco discovered that magnetic interference from the starter/battery cable could trigger “false” sparks at low RPM—especially during cranking. Pickup coils are selected based on engine family. Ignition coils are then selected based on which pickup coil was selected.
chart did not copy & paste too well...
Table 1. Pickup Coil and Coil-in-cap Ignition Coil Selection for Traditional V-8 Engines
Pickup Coil
color code
Ignition Coil
color code
Red and White
Red and Yellow
Red and Yellow
Oldsmobile except Toro
Red and White
Oldsmobile Toronado
Red and Yellow
Red and White

So, for the “traditional” V-8 engines, Chevrolet, Cadillac, and Olds Toronado use the yellow-coded pickup coil, and because they use the yellow pickup coil, they use the red and yellow ignition coil. Put another way, the yellow coils are a matched set. Buick, and Oldsmobile except Toronado, use the blue/black pickup coil, and therefore use the red and white ignition coil. Pontiac uses the clear coded pickup coil. It is wound the same way as the blue/black coil, but has longer leads to physically fit in the Pontiac version of the HEI distributor. Therefore it, too, uses the red and white ignition coil. Many parts catalogs indicate the wrong pickup and ignition coils for Olds Toronados. The Delco service information I’ve paraphrased here can be found at:
i knew i seen this on the site before

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