Strange failure

[conedriver]

At the last local SCCA autocross of the year, at the end of the last run, the car shut down just as my wife crossed the finish line. A quick inspection revealed the failure pictured below. Has anyone else ever had this happen?

[Tifosi]

Yeah, but not on an Alfa.

It's generally associated with the rotor getting a bit wobbly, then getting evil from there.

From the look of it I'd hazard the outer rivet on the contact plate got a bit loose and let the contact rise up a bit where it started beating things and eventually it rotated on the center rivet and shoved out through the hole at about the 4 o'clock position on the cap as it sits in the photo.

Or conversely, the rotor rose up/came unseated on the dizzy hub a bit and the actual cap contact points did the rivet in.

Just a quick guess on that mind you.

[lowmileage]

Worst I've ever had on another car was a cracked distribtor cap that I just happen to notice when checking the points. It was supposingly a High performance Accel brand.

[Alfacliff]

A friends car did that once, had a stuck float and lots of gas in the oil. bad seaal let gas fu=mes build up in dist cap till he started his car BOOM .
cliff

[conedriver]

Hi Tifosi,

You're correct. It appeared that one of the two rivets holding the contact to the rotor either came loose, or failed. Either sooner or later, the contact spun outward where you can see it sliced into the distributor cap contacts (but in correct alignment). At some point, things came together and everything cracked. After installing a new rotor and cap, I was able to start the car, back off the trailer and drive into the garage. BTW, the dizzy was a couple of months old from a rebuild and crane ingnition installation from Wes Ingram, so the shaft should be in good shape. The rotor and cap, however, were used and supplied by me.

Quote:

Originally Posted by Tifosi Yeah, but not on an Alfa. It's generally associated with the rotor getting a bit wobbly, then getting evil from there. From the look of it I'd hazard the outer rivet on the contact plate got a bit loose and let the contact rise up a bit where it started beating things and eventually it rotated on the center rivet and shoved out through the hole at about the 4 o'clock position on the cap as it sits in the photo. Or conversely, the rotor rose up/came unseated on the dizzy hub a bit and the actual cap contact points did the rivet in. Just a quick guess on that mind you.