Hi everyone, I am having trouble with my C3 ignition. I'm running original HEI distributor. It has blown 1 ignition module and 2 coils since Holley Sniper EFI conversion. I have only driven about 300 miles since the conversion. The ignition module was original GM. The current one is a Davis - Dyna Mod (currently testing good). The 1st coil blown was a MSD. The second is the original one that came with the car. I can't see a brand on it but it has a gray body with only 2 wires coming out it. It uses a ground strap attached to one of the mounting screws. According to the original owner, it ran well on the car for years and years. I'm attaching pictures of what the distributor cap, rotor and coil looks like after this most recent blow out. I appreciate any thoughts on what could be causing this problem. Thanks.

distributor contacts:


carbon brush



rotor tip


rotor spring


coil


distributor cap

 

No one is beating a path to your door, so I will take a shot at this.

You actually had a fire going inside the dist cap and likely didn't even know it.
Not familiar with Holley Sniper system. Does that unit run off of the IGN system?

To me, when something burns like that, I would think that a poor ground is lurking somewhere in the ING system. Juice is not getting to the plugs. But why?

A couple of things come to mind. The GRD wire on one corner of the coil. Those coils come with a rust resistant coating on them. You could try grinding one corner of the coil down to bare metal then attach your GRD wire.
Next, double check all color coded wires going into the dist cap. The way to do this properly is with the dust cover off the coil. Then you can make sure black, yellow & red wires are in their correct spot. Sorry, I do not have a drawing of the wires.
Behind the Hot Lead and Tach wire on the cap is another terminal. Is it possible that was installed backwards? I label mine to make sure its not, ever.

And last. I would suspect the coils Spring Button. Looks fried in the photo. As I recall, those buttons come in two types. High resistance & low resistance.
Whats the difference? I do not know. What determines high or low? I believe its the gauge of the spring.

Obviously you need a new cap & rotor. You could snoop around on Summit Racing and see what they have for coil buttons too.

 

Thanks HeadsU.P. for the feedback. Scary stuff; On my Sniper setup, I am setting my timing the old fashion way by gapping the plugs and using a timing light. I just received my new coil, dist cap and rotor. I will do all the checks you mentioned when reinstalling them. Hope to figure this one out fast.

 

I have heard of people applying dielectric grease on that rubber insulating washer before installing it and the spring button.
I don't know if that is necessary or not and I don't know if people apply to both sides of the washer.

Maybe someone will chime in who has done this.

You seem to have a lot of voltage flying around, burning things up for some reason. So maybe the issues are in the cap. IDK.

 

When you say the coils went, what actually happened to them? Did you have a failure on the primary or secondary?

 

I know it's the secondary on the second one; I believe so on the 1st one, too. I will get over to my storage unit to check the 1st one tomorrow. Thanks.

 

How are your wires, and what spark plug gap do you have?

 

Wires are new - no more than 500 miles on them. I gapped plugs at .045.

 

OK. Just make sure the brush in the cap is actually making contact with the rotor. Has anyone monitored the secondary firing voltage values?

 

Ok, thanks; I will; No, How do i go about monitoring the secondary firing voltage values? Thanks.

 

Do you know anyone who has a scope? You can monitor voltages, burn times, and firing patterns to determine if it's one cylinder or many.

 

Ah ok, I don't know anyone buy I will look further into it. Thanks.