Identify story about time-travelling assassin that can kill by touching people

Please help me identify a short story about a time-travelling assassin. His
time machine is a car. He gets assignments over the car radio from "The
Oracle." His 2 henchmen are named Chubb and Harley. He can kill by touching
people. Sounds like it was written in the 60s because an assignment takes him to a sort-of hippy cult house, a bit like Charles Manson.