Ignition Lead Organisers

thingiverse

I was under the bonnet of my Classic Rangey trying to solve an intermittent missfire when I discovered a simple solution - replacing all the HT leads. The original lead organisers had vanished into thin air, leaving me with no choice but to spend money on new ones. To protect them, I designed and printed these organizers myself. To get started, I measured everything carefully using my trusty vernier caliper. The measurements are in millimeters, as per usual. These organizers needed to do two main jobs: hold the leads in place and keep them at a safe distance to prevent crosstalk. So, all I had to measure was the diameter of the leads themselves - exactly 8mm. Each organizer started life as a basic 14x14mm square, extruded to 6mm thickness. Initially, I chose this thickness because it would fit in the engine bay, but it looked ugly and I wasn't happy with it. The rest were made thicker, at 4mm, printed at 75% density for added strength. Each cutout began as an 8mm ID, 100 face circle, recessed by 3mm beyond the edge, spaced 8mm apart for lead separation. A line was drawn from the center of the circle to the nearest edge of the rectangle. I whipped out my calculator (shhh!) and calculated two-thirds of the diameter - 2(8mm/3) = 5.33mm. I later added an extra 1mm, splitting this figure in two gave me 3.1mm. Two new vertices were created along the edge, each 3.1mm from the intersection of the center-edge line and the edge. From these vertices, a line was drawn parallel to the previous line, intersecting the circle. This keyhole shape was then extruded back to zero, removing material and leaving an open, keyhole-shaped hole for HT lead entry and retention. The cutout fits spark leads just a bit too snugly, but they stay in place once clipped. If I need to reprint these, I'll add another 1mm (two extra mm total) to the opening. I've already printed and installed these organizers, so I'll update the design later with the additional space. In some cases, leads must cross over each other, so I designed additional pieces to hold them in place while keeping a safe distance to prevent crosstalk.