bobb

Hi Guys,

Does anyone know why there are so many different 12v ignition coils used in Olds and other GM applications? I'm talking point distributor coils, not the newer stuff. What's the difference between a 216 B-R Delco Remy coil and a 292 B-R? Or any of the other designations. Seems Chevelles, Camaros, Cutlass, Skylark....all use different number/letter designations....but they're just 12V coils. Why so many different ones? Also, anybody know what those designations mean?

thanks,
bob

matt69olds

I think it has something to do with the direction the distributor rotates. With HEI distributors, the ones with white and red wires are for different rotation than yellow and red. Don't recall what coil goes with which direction.

rustyroger

Engines have different requirements from their coils, an 8Cyl engine has to produce twice as many sparks as a 4cyl for a given rpm.
A coil doesn't know which way round a distributor rotates, it simply responds to the points opening, producing a high voltage spark when the points open. At 3600 rpm that is 240 times a second for an 8 cyl engine. Coils need time to build up the voltage necessary to jump the plug gap, to make one capable of handling a high revving V8 costs more than one dealing with a low speed 4 pot.
Moral of the story; use the correct coil for your application.

oldcutlass

Some coils are wound different to produce more spark voltage, they also may have different core materials.

don71

Bob, check out the link below. I think you will find your answer. If not, you'll certainly find it interesting. Its a large page, so scroll down to about the last 25% of the page.

Please note that its a chevy page.....but the author I believe is a GM tech and for sure is an Oldsmobile owner. Have fun.

http://www.chevelles.com/techref/ftecref5.html

oldcutlass

Very informative! A lot of good info there! However I believe he was referring to non-HEI. There are many different coils on the market based on engine size, mounting position, and more importantly output voltage.

bobb

H Guys,

I hear what your saying, but I'm still not sure it explains why GM had 20+ 12V Neg ground coils for its V8 engines in 1970. All that's in a coils is a core, primary and secondary windings, and some oil to keep it all cool. No real rocket science here. You can manipulate the number of primary and secondary windings.....but that's about it. They just weren't that evolved back then with different core materials, etc. All V8s idle at the same speed, so on the low end all the coils have to produce the same minimum spark energy at that RPM. At the top end there is some difference, but a coil that makes full voltage to 6500 rpm for a small block screamer will also make it at 5000 rpm for a big block application. I've looked at the different coils at swap meets, etc...and they are all the same size and construction......so I'm just not getting it.

regards,
bob

oldcutlass

Some had different winding ratios from 85-1 to 100+ to 1. Some were epoxy filled and others were oil, some leakage rates were different (which effected stored energy at different rpm's), and some had a built in ballast resistor while others used an external. I don't know which pn's were for which.