Hello everyone, this is my first post.
I have been searching for sometime and have not found the answer to my question. Can the primary side of the coil fire the spark plugs? The reason I ask is because I have been TSing the ignition for a rich condition on one plug (fine carbon soot #6) and cannot find a schematic of the coil. I have the autolite 3924 8.5kohms, the summit 8mm wire 455ohms same from inside the cap to end of wire and then went to the coil. Everywhere I have looked online including my chilton says to test secondary output to bat+ and tach terminal and come up with 8.5k-30kohms. Mine comes up with an open. The secondary output does read 11.5kohm to the center ground pin. I tested another coil from an HEI which has no black wire coming from the middle of it and got 11.5k secondary to Bat+ and Tach and open secondary to ground. The car seems to run good with the (bad) coil but that could explain my eyes burning if the primary side provides a strong enough fire to burn but not burn completely. I have a 68 camaro by the way and I do have the 12v wire installed. Long post, I know, but I'm puzzled. BTW I like all the knowledge on this board.

You've probably been here:

http://www.megamanual.com/ms2/GM_7pinHEI.htm

My HEI is a 4 pin but I just ended up buying a new stock coil, tested it, and those readings match the supposed bad one. I dont get it; unless there are 2 different coils one with a center black wire and one without, and both are supposed to be tested differently. oh well, Ive got header problems to deal with before the ignition matters anyway.

Can the primary side of the coil fire the spark plugs?


I seriously doubt the flyback from the primary circuit could fire the plug. Keep in mind that if the secondary is open, a spark can still jump the gap within the coil and fire the plug, although with a weaker spark.

I've seen ignition coils that won't ohm out. I'm not sure why. It's as if they have a capacitor in series with the winding, but I doubt it's a capacitor.

I haven't performed the test you're doing so I can't comment on the readings you see. There are a multitude of different configurations as the link above eludes to. Perhaps the diagnosis tree you're following is for a different model.

You might check your local library for a professional service manual. Occationally you'll see block schematics that give you some indication of how the guts are arranged.

Thanks for the reply, I bought a new one and it measures the same way so I will return it. Back to square one. I will just run the old one. I need to focus on other problems :confused:.

To end the story in case anyone else has the problem, I went and bought a coil tester. It just looks like a spark plug with a 1/2"gap that is about what it takes for a healthy coil to jump. Their is an aligator clip on the plug body so you can position it in a good place to see as you crank. There was a healthy spark. Threw it all back together with a different carb and the richness was reduced. I think my old carb had an internal fuel leak as the base gasket was stained and damp with fuel, causing the eye burning experience. Thanks again for the help.