This may come in handy for other V8 HEI folks with a strang miss fire.

Broken HEI dizzy cap button

Guess I found my random miss fire. I first started by hooking up a timing light to each plug wire. Trying to see if its a wire or other problem.
I was able to see the light skip a beat in tune when the engine skipped a beat. But the darn thing didn't do it constant and it seemed every cylinder would skip now and then.

I almost started with the plugs but decided to check the cap. And it was clean and good, not even close to worn. Then I noticed my Dizzy button was barley sticking out of the cap.

The sucker broke off and has been grinding n archin it self shorter n shorter.

 

But, that begs a question - why did it break, and will it happen again?

 

The old and new one look to be made the same with a sandwich of materials or a coating. like both ends are some type of cooper looking stuff with a section of black in the middle. It broke at the bond line of the two layers. near the top.

I kinda think it all just carbon but the ends are treated. One end is pressed into that brass like washer that holds the spring and the other end is what rides on the rotor. So I kinda assume the copper like stuff make the carbon hard enough to to do them job on the ends but they of course don't bother treating the middle.

So any of them could crack or break easy right there. copper parts are tough, razor blade doesn't do much damage, in the black area it scratches deep..

 

Feels good when you finally nail a strange problem like that, doesn't it. "Hey, here's the problem right here!"

I can't recall seeing one break like that before. Possibly broken when originally installed? You may never know. Drop in a new one and make sure this one is in there right. Cap, button, rubber donut, coil- in that order.

 

Been there, done that, same thing lol

Its a dumb one, but easy to fix once you find it.

later
Jeremy