Charles © Doan
Spark plugs and description
I finished the spark plugs and wired them in. I first did some research on the web, and also in my 1922 edition of the Dykes automobile encyclopedia. I learned that by 1922 the S.A.E. had standardized on 7/8-18 threaded plugs, with both 7/8 and 1 1/8 hexes. I bought some 1 mm brass nuts from the Scale Hardware Co. http://www.scalehardware.com/ that were dead nuts on for a 7/8 hex in 1/16th scale. I used .035 Plastruct styrene rods for the electrodes. Using a drill press, I turned some grooves in 3 of them. I left one as a smooth body design for variety. I drilled out one end to accept an H.O. scale valve stem from my parts box (these represent the older screw on type terminal heads.) I tried adding some tiny lettering to the electrode from a Microscale decal sheet, but I couldn’t get the decal film to disappear. I blackened the 1 mm nut to simulate the older black oxide finish, and cut a piece of .048 stainless tubing for the body which was then painted black. I assembled everything (except the valve stems) in a simple jig and glued the plugs into the cylinder head.
For the ignition wires, I used .022 solder. I cut some 1” lengths and rolled them with a diamond file for “cloth” texture (which all but disappeared after painting). I then squished the ends with pliers and filed them to shape for the terminals. After drilling the ends for the valve stem, I carefully curved four pieces from each plug to the back of the coil box. Then I glued the valve stem into the hole in the solder “terminal” to form a pin. The valve wheel is about .025 thousands diameter, and of course I only had four, so this operation was bit nerve wracking! To help handle the tiny parts I put some spit on my work mat and used tweezers to assemble the pieces in the puddle. This serves two functions; it helps keep tiny pieces from doing the “fatal tweezer flick”, and once people find this out, it tends to deter them from wanting to touch my models! Once the parts were together, I let them dry and placed a drop of super glue on the valve stem to hold.
I blackened each wire with Blacken-it and painted them with thinned Floquil Earth. Each one was then carefully glued on and dusted with Bragdon powders. I puddled some rust (thinned Gouache) in the plug mounting spots, a common thing on old flatheads. The number one plug shows signs of some serious oil blow-by. Since making several matching anythings is tough for me, I am glad this isn’t a V8!