Rough idle turned to crank then ka-thunk

I had a small block that developed a misfire on my way to work 50 miles from my house.

Nothing I did fixed it. Had it towed home.

At home with more tools and test equipment. Nothing to explain the problem.

I grabbed the original dist that had been in a box on the shelf since the 80s and popped it in. Fired right up and ran like a champ.

The dist I pulled had about 1/4" of up and down movement on the shaft the rotor sits.

I also noted the the rotor had a bad circle on the contact and the center pin on the cap was disintegrated.

I came to the conclusion the rotor was moving up and down enough to make and break contact to the cap causing the misfire.


Just something to look at.