Hints & Tips

Sparkplug Wiring

Spark plug wires are one of the most important engine compartment enhancements in a scale model. With the quality of today's models, if you are adding only one detail, this should be it. Before doing any work, you must decide what type of plug wires the car you are replicating uses. In some engines you don't see the wires like the LS1. Typically, the newer the car, the less visible the wires. 60's engines look good with wires routed over the valve covers. Get as much reference material as possible. Buy the real car! (just kidding). There are several plug wire types like stock, high performance, racing and braided among others.

Wires:

The most common mistakes made by modelers is using a plug wire too thick that doesn't look good, and routing the wires in a straight line. Stock wires are usually 7mm thick and dull in color (black, gray, blue etc.) This wire type is usually routed so it is not very visible (i.e. under the exhaust manifold). In 1/24 or 1/25 scale, this is around 0.29 mm. A good source for this is electrical stranded wire. This wire is thick but it is made out of many thin strands and come in many sizes. Just a few inches of wire will provide more than enough for a couple of models. Drill small holes where the spark plugs should be located. The deeper the better, if it goes all the way thru, that’s even better. Form the wire from the plug location backwards. When bending, remember that the plug wires are flexible and drape from weight. If routing over valve covers, drape over the intake manifold. On most Corvettes, a shield covers the distributor. If this is your case, drill the sides of the shield and slide the wires in. If the distributor is exposed, then drill small holes in it and make sure the wire curves to the top. Also remember the ignition coil if exposed. Just loop a wire from the center of the coil to the center of the distributor. Depending on the coil, you can use ultra thin wire, like radio antenna filaments, to wire the two little connections of the coil. (12V and ground). It will add a realistic look.

Since this type of wire holds its shape, after forming it, remove it and paint it with flat colors. If you want some shine on them, use some gloss coat, but do not paint, using gloss paint colors.

Custom and Hi Performance wires are usually thicker. 8mm are a popular size. This is about 1/3 mm (.33) in scale. For this application, there are several choices. "Wire wrapping" material is a wire that is used in prototype electronics. This wire is available at Radio Shack and comes in many colors and several sizes. The 0.30mm is the best for this application. The wire is a little bit glossy which looks nice, but you can use dullcoat over it. The procedure is the same. If you need to replicate thicker wires, you can use phone line cable, which is solid copper with insulation using the same procedure.

Some plug wires are braided to prevent interference with radio equipment. (i.e. 60's big block Corvettes). For this type of wire, you can use a nylon stranded sewing thread. Choose a light color, so it is easier to paint chrome-silver. After drying, use aluminum paint to slightly reduce the glossy chrome finish. In this case, paint it before forming. After mounting it is easy to touch-up any scrapes with paint. Remember that braided wires are still flexible, but not as much as regular wires, so they don’t drape as much.

Sparkplug Boots:

To replicate the end "boots" of the wires, you can use phone cable insulation with a dab of white glue. You can also add a custom touch by using different colors of insulation or using contrasting colors (i.e. blue wires with yellow caps etc.)

Distributor:

Wiring the correct firing order is great, but if you don't want to spend a lot of time doing this (being lazy), wire the engine into two parts. Those wires to the left of the distributor and other side to the right of the distributor so it looks like the correct order. Aftermarket pre-wired distributors are also available.

Summary

Scale spark plug wires are available in correct sizes and in many colors, but if you love scratchbuilding, and don’t mind taking some extra time doing it, or if you are on a tight budget, try any of these suggestions. Keep experimenting with new materials. Who knows what you may come up with….

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Page updated  01/03/00