By Neil Van Zile (Fine Scale Modeler, July 1994)

Making scale spark plug wires

Not a long time ago, the best way for make spark plug wires in scale was greasing with wax sew thread. Now, thanks to the electronics advances, we can use true wires for all type of cables and hoses. Several companies sell wires in scale directly, of all sizes and colors, as well as ignition coils, distributors and other details (Fig 1).

Here we see the easy way to improve the engine detail. (Left) Predrilled distributor and coil, both of turned aluminum from Repro company. (Right) An increased photo of ignition coils and clips from Detail Masters. All the pieces of the photos are for vehicles in 1/24-1/25 scales.

Taking measures

Measure the wires diameter carefully, if one of them is not in scale will seem wrong. The best instrument of measurement in these cases is the caliber, but it is an expensive instrument, it cost between u$s15 and u$s50, and can that much more. If you dont want to make a great investment, simply see the attached list, that shows several diameters for the different scales. The real spark plug wires go from the factory standard in black color to the super thicknesses, of yellow or red shining color of the dragsters cars. We can see in the list of measures that a diameter can correspond to several applications. That is good, because many companies sell only one measure (normally between 0,017 and 0,019 inch of diameter). The measure is less critical if you add only the spark plug wires to your engine. On the contrary, if you are going to superdetail the engine and imitate each small wire and hose, the measures has more importance, because the relative sizes have much to do. Stick the wires with CA glue, the cement for plastic does not act in the most of the materials used like isolation. In addition you will need a small hand drill hand and a set of small, drilling bits, from 0,013 to 0.039 inches. A drill bit of 0,019 inch is the standard size that adapts to everything.

Drilling the distributor cap

Sandpaper the distributor cap until leaving it flat, soon marks the center of each wire exit with the help of a fine needle mounted in the hand drill (Fig 2). This help to center the hole correctly. Relax the back end of the hand drill so that it turns freely (Fig 3), supports this end in your hands palm and smoothly turns towards both directions with the thumb and the greater finger; it is possible to drill very small holes this way, but do it smoothly and without applying pressure, because the drill bits of this size are very fragile.

Figure 2                                                      Figure 3

Placing and gluing wires

Firstly, studie the engine that you are constructing. Most of the distribution wires are placed in their ignition order. In the street cars the wires can be crossed to separate those of successive ignition, and to come up that they separe. The race cars have different configurations. Place the wires in the distributor firstly, cutting segments of 2 to 3 inches, glue them with CA glue to the distributor cap and mount it in the engine. After the glue dry (normally to a day for other) place each wire in its corresponding hole in the cylinder head. Verify each wire and cut it to the necessary length, leave whenever on a little, so that see real the “fall”  and route of the wires. In order to imitate the spark plug wires terminals, cut the isolate of a greater wire (like telephone wire) and put it in the end of the smallest wire (Fig 4).

Figure 4

Thats simple

You can also take a short cut buying distributor caps and spark plug wires in scale. But if you works carefully –and does not use too much glue- can superdetail easily and cleanly any engine. Practice: begin superdetailing that F-1 car in 1/43 scale today!

Scale spark plug wire table (in inches)