Any of you guys ever ran spark plug wires through a small length of stainless tube bent around a exhaust manifold for a (nice looking and formed) heat shield? Spark plug wires are 8mm, around 1/4" and the ID of the stainless tube is .3675, just under 3/8." I would rather not (hide) rout the wires underneath or behind the exhaust manifold. Want 'em outside of the manifolds for the whole world to see. I fitted up a set of those 1" OD, 6" long "heat" socks/covers, that are offered for sale by everybody. But, to me, they look on the "sloppy" side, as a "afterthought". Too big in diameter, with a itty-bitty wire up through the middle. The 2 front cly's on both sides, those covers are rubbing the hood sides, and are shoved directly on the manifolds. I see the Flathead motors have their wires ran though long lengths of metal tubing for heat shields. I am not thinking of a long tube like the Flatheads, just somehting 4" or so long, polished, bent around the outside of the manifold with the plug wire ran through the tubing to keep the wires off the manifold. Or, is this one of those "mad scientists" hare brained, conquer the world ideas, that shouldn't be thought of? Thanks
There would be pros and cons as far as actual thermal protection goes. PRO You can set the distance from the manifold, and prevent unwanted contact It can serve as a heat sink/spreader, conducting heat from a localized hot spot to a cooler bolted area, or just spreading heat in general to eliminate localized hot spots. This is very application dependent, and limited effectiveness. Aluminum conducts 14X better, copper conducts 30X better. Polished stainless can have a very low emissivity. Not as good as aluminum at 0.05, but pretty good at ~0.08. This makes it reject radiative heat transfer very well and can make a big difference in protecting wires from radiant manifold heat. CON The conductivity that makes it a potential heat sink for getting rid of heat can also transfer the heat straight to the wire. It'd be best to sleeve the wire in something well insulating before putting it in the stainless tube. Dirty/weathered stainless has an emissivity 10X worse than polished stainless, so if you don't keep it clean/shiny, your radiation protection is greatly reduced--but still there. For reference, 8mm is quite close to 5/16", while 1/4" is closer to 6mm. I personally would probably pick a tube with a slightly bigger ID and try to insulate the wire from the tube. Best of both worlds at that point. If implemented correctly, I think your idea has good potential to work well, and look much better than the sleeves you're talking about.
THANKS for the in-depth information! Very well articulated! I can't get 7/16 OD 3/8 ID stainless tube to bend around the manifold without kinking. Even filling it with very fine sand. So the polished stainless tube idea is out. Searched for copper tube as you suggested. There is no "soft" (bendable) 7/16 OD, 3/8 ID copper tubing made. Nearest size is 1/2 OD, 7/16 ID. Again, looks like "feces" with a big open end with a itty-bitty wire up through the middle. In the "umpteenth" time googling, "form fitting flexible spark plug wire insulators." A different site popped up. Ton's (Ton, not Tom) Performance. He has 4 different almost form fitting plug wire insulators! Plus more different kinds of plug wires and hardware, than you can throw a spark plug at! Never knew this place even existed! Just got through sending him a inquirey, I'll post what he sez, in case someone else needs any off the wall spark plug wire ideas/parts.
Use stainless overbraid A dusting of heat resistant clear lacquer makes them go stiff. Or clear heatshrink
This may or may not be of help to you....not sure how much of a bend you're lookin at. I used some vintage aircraft flexible SS conduit for my head light wiring. It has .375 ID/.438 OD
You're welcome, and I should've thought to look at Ton's! I blundered onto their site last year, I think I was pricing out cloth wiring for my wife's '48 Pontiac. I haven't ordered anything from them yet, but I remember being impressed by the things available on their site.
McMaster Carr has it by the foot. A lot of electrical jobbers have it. I think hardware stores normally carry zinc plated steel...not sure on stainless but you can check. Quality will vary from vendor to vendor also. https://www.mcmaster.com/products/flexible-conduit/flexible-metal-conduit/
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