Correct Date-Coded Plug Wires

You can have an 800-horsepower engine, but without the spark to fire it off, it's just another chunk of inanimate metal. Obviously, plug wires are an integral part of your ignition system but they can vary greatly in how efficiently they work. There are several thicknesses of wire from a measly 6mm all the way up to monster 12mm. But at some point along the way you are simply dealing with overkill.


The cars of the Fifties and Sixties used 6mm and 7mm wire that came from the factory with date codes applied along the length of the wire. Each manufacturer used their specific supplier for plug wire, i.e. Ford used Motorcraft and GM used Packard or AC Delco wire. The manufacture's name was also on the wire. Until several years ago, replacement plug wires were generic over-the-counter types that could be purchased tailored to fit, or you cut to length as a do-it-yourselfer. Many aftermarket ignition manufacturers also carry their own branded wiring to go with their ignition kits. Now, for the restoration purist, correct date-coded plug wires are available with the original information printed on each wire. The samples shown here from a restoration parts supplier are GM wire dated 1964 and a generic replacement wire available at your auto parts store. If you're a resto fanatic, you need the wiring date-coded for your car.

OTC
These are replacement GM Packard wires purchased over the counter. They are tailored for the application (a 1970 GM big-block) and carry a date of 3Q87, or 1987. They are rather small at 7mm by today's mega-wire standards, but they get the job done and look like the originals. They are also radio static-suppression wires. That means that they block the engine firing noise sometimes heard through the radio. Today's radios don't suffer from the same malady. When purchasing over-the-counter wires, make sure you get the right spark plug boot for your application. They come with straight, 60-degree and 90-degree bends to clear the exhaust manifolds or headers.

Date-Coded
Here we see wires with the correct date codes for the vehicle. They are Packard wires dated 2-Q-64 for an early-production (September) 1965 vehicle. If you're planning on entering judged shows, and particularly concours competition, these wires are a must. The average cost is around $60 for a correct set and can be obtained from restoration parts suppliers specializing in your brand of vehicle. Consult with your supplier, giving them the month and date (if possible) that your vehicle was made and they can send you the time frame that will be correct. The date will normally be several months before the vehicle was manufactured in the case of GM products.