In spark contrast: The difference between plugs for classic and modern cars Rob Siegel 25 June 2018 Share Let’s talk about spark. In modern, computer-controlled cars, ignition is reliable to the point where you rarely consider that it might fail. You have coil-on plugs, also called stick coils, snapped onto the tops of spark plugs, with not even a plug wire between them. The stick coils and plugs are typically hidden inside the engine under a plastic cover that looks like the top of a Shop-Vac. There’s no distributor, because the functions of advancing the spark with increasing engine rpm and distributing it to each cylinder are performed electronically, with everything controlled by the car’s electronic control unit, or ECU. Something like a bad crankshaft position sensor might prevent the ignition system from being triggered, but it’s rare for the entire ignition system to go bad. In contrast, everything on vintage cars is analog and in plain sight. A single conventional ignition coil is connected to a distributor cap via a fat plug wire. Individual wires then connect the cap to each spark plug. As the engine rotates, the distributor spins around, opening and closing the points that trigger the spark. The rotor inside the cap distributes the spark in round-robin fashion to each plug. With such wildly different computerized and analog control mechanisms, the similar-looking spark plugs used by new and vintage cars are, indeed, different. Hagerty member John Veenstra writes:
