Mystery shudder

[448Scamp]

I’ve been using the Mallory ceramic booted wires. I suppose they are MSD wires with the Mallory name on them but they are cheaper than the MSD. The last 3 sets I bought were only 79 dollars. You can’t beat that.

 

[Boduke]

Fyi. I once had a vibration at rev like your describing. A driveline vibration. Turned out to be a loose harmonic balancer. There was a missing washer and the bolt had bottomed out in the crank nose. Chased that one for almost a year.